Engine Cooling System Chevrolet Cab & Chassis Silverado 3500 HD

Fastener Tightening Specifications

Scheme 1

Scheme 2

Scheme 3

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Engine Cooling

Begin the system diagnosis with the diagnostic system check. Refer to Diagnostic System Check - Vehicle . The Diagnostic System Check - Vehicle will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuits
3. The identification of any stored DTCs and their status

The use of the Diagnostic System Check - Vehicle will identify the correct procedure for diagnosing the system and where the procedure is located.

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The engine control module (ECM) commands the fans ON in high speed or low speed. In low speed, the fans are configured in series. In high speed, the fans are configured in parallel.

In low speed operation, the ECM applies ground to the coil side of the low speed relay. Voltage is applied directly to the left cooling fan through the switch side of the low speed relay. The right fan is connected in series to the left fan through the de-energized series/parallel relay, which is the FAN CNTRL relay, so that both fans operate at low speed.

In high speed operation, the ECM applies a ground to the coil side of the low speed relay, the series/parallel relay, and the high speed relay. Voltage is applied directly to the right cooling fan through the switch side of the high speed relay. The left cooling fan obtains voltage through the low speed relay and ground through the series/parallel relay.

When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage. If the ECM detects that the actual voltage of the relay control circuit is different than the expected voltage, DTC P0480 or P0481 will set and the affected ECM driver will be disabled.

Conditions for Running the DTC

1. The ignition is ON.
2. The system voltage is between 9-18 volts.
3. The relay control circuit is transitioned from OFF to ON, or ON to OFF.

Conditions for Setting the DTC

1. An improper voltage level has been detected on the cooling fan relay control circuit.
2. The condition must be present for a minimum of 30 seconds.

Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480 and P0481 are Type B DTCs.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

1. «Component Connector End Views»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-starting-point-connector-end-views)
2. «Powertrain Component Views»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/electrical-component-locations/#wiring-systems-and-power-management-master-electrical-component-list-component-views-1-of-2)
3. «Electrical Center Identification Views»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/electrical-component-locations/#wiring-systems-and-power-management-component-views-2-of-2)

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

Circuit/System Verification

Verify cooling fan operation using the scan tool commands listed below

1. Fan Relay 1 ON-Both fans run at low speed.
2. Fan Relays 2 and 3 ON-The right fan runs at high speed, the left fan is OFF.
3. Fan Relays 1, 2 and 3 ON-Both fans run at high speed.

Circuit/System Testing

1. Ignition OFF, disconnect the 3 cooling fan relays listed below. FAN LO relay FAN CNTRL relay FAN HI relay
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 85 of each relay and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
3. Verify that a test lamp does not illuminate between the ignition circuit terminal 85 and the control circuit terminal 86 of each relay. If the test lamp illuminates, test the control circuit for a short to ground. If the circuit test normal, replace the ECM.
4. Remove the test lamp.
5. Ignition ON, command the affected relay ON using a scan tool. Verify the affected scan tool FC Relay Control Ckt. Short Volts Test Status Parameter is OK. For the FAN LO relay, use the scan tool Fan Relay 1 command. For the FAN CNTRL and FAN HI relays, use the scan tool Relay 2 and 3 command. If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
6. Install a 3A fused jumper wire between the control circuit terminal 86 and the ignition circuit terminal 85. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt Short Volts Test Status Parameter is Fault. If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
7. If all circuits and the ECM test normal, replace the affected relay.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Underhood Electrical Center or Junction Block Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
3. «Engine Coolant Fan Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
4. «Control Module References»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an over-termperature condition. This condition occurs when the coolant temperature is above a calibrated value for a calibrated length of time. The ECM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the ECM is able to reduce the temperature of the coolant.

1. The engine is running.
2. DTC P0117 or P0118 are not set.

Coolant temperature more than 132°C (270°F) for greater than 10 seconds.

1. DTC P1258 is a Type A DTC.
2. The engine will operate in the Overheated Engine Protection Operating Mode.
3. The engine coolant temperature indicator lamp, if equipped, will illuminate.
4. The driver information center (DIC), if equipped, may display a message.

Conditions for Clearing the DTC

DTC P1258 is a Type A DTC.

Description and Operation

1. «Cooling System Description and Operation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Instrument Cluster Description and Operation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
3. «Indicator/Warning Message Description and Operation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)
4. «Audible Warnings Description and Operation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages__audible-warnings-description-and-operation)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Observe the engine coolant level. The engine coolant level should be within operating range. Refer to Capacities - Approximate Fluid, and Engine Coolant in the Owner's Manual.
2. Ensure that the vehicle has the correct engine coolant, with correct concentration, and is not old, contaminated or contains additives. Refer to Recommended Fluids and Lubricants in the Owner's Manual.
3. Inspect the cooling system for the following: Leaks Kinked or pinched hoses, especially at the radiator Loose, missing, or damaged radiator air seals or deflectors The radiator and A/C condenser for any air flow obstructions or bent fins-Refer to «Symptoms - Engine Cooling»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__symptoms-engine-cooling) .
4. Command the cooling fan speed from 0% to 100% with a scan tool. If the fan speed does not transition with the commanded states, refer to «Cooling Fan Inoperative (w/o LFA)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Inoperative (w/LFA)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Test the thermostat for correct operation. Refer to «Thermostat Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Test the engine cooling system for overheating. Refer to «Engine Overheating»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating) .
3. Inspect the water pump and coolant flow for correct operation. Refer to «Water Pump Replacement (LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Water Pump Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Water Pump Replacement (LH6, LY2, LY5, and LMG)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Water Pump Replacement (LY6, L76, and L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Water Pump Replacement (LFA)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Inspect the engine for worn/leaking/cracked cylinder heads and engine block. Refer to «Coolant in Combustion Chamber»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-1-of-5__coolant-in-combustion-chamber) and «Coolant in Engine Oil»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-1-of-5__coolant-in-engine-oil) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Symptoms - Engine Cooling

1. «Cooling System Description and Operation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Cooling Fan Description and Operation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Cooling System. Refer to «Checking Aftermarket Accessories»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Cooling Fan Always On»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Cooling Fan Inoperative (w/o LFA)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Inoperative (w/LFA)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
3. «Engine Overheating»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
4. «Loss of Coolant»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
5. «Thermostat Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
6. «Engine Fails To Reach Normal Operating Temperature»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__engine-fails-to-reach-normal-operating)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The low engine coolant level indicator is controlled by the HVAC control module. The normal state of the engine coolant level switch is closed when in contact with coolant.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

The low coolant indicator should be OFF with the engine coolant at the proper level.

1. Ignition OFF, disconnect the harness connector at the coolant level switch.
2. Install a 3A fused jumper wire between the signal circuit terminal and ground.
3. Engine running, verify the low coolant indicator turns OFF. If the indicator does not turn OFF, test the signal circuit for an open/high resistance. If the indicator turns OFF, test the ground circuit for an open/high resistance.
4. If all circuits test normal, replace the coolant level switch.

1. «Radiator Surge Tank Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Surge Tank Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Control Module References»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)
3. «Instrument Cluster Replacement (Without RPO SLT)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages) or «Instrument Cluster Replacement (With RPO SLT)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)

Repair Verification

Verify that the low coolant indicator is OFF with the engine coolant at the proper level.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the fan low relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the fan low relay, which is fed by the fan 1 fuse. The right fan is connected in series to the left fan through the de-energized fan control relay so that both operate at low speed.

In high speed operation, the ECM applies a ground to the coil side of the fan low relay, the fan control relay, and the fan high relay. On the fan high relay, the energized coil closes the switch side of the relay and applies voltage directly to the right cooling fan through the switch side of the relay, which is fed by the fan 2 fuse. At the same time, the ECM energizes fan control relay pulling the switch side over, providing a direct path to ground for the left cooling fan, which has voltage applied through the energized fan low relay. In high speed mode, the fans are operated as a parallel circuit with full voltage applied to each.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

1. If DTCs P0480 or P0481 are set, perform those diagnostics first.
2. Ignition ON, verify with a scan tool that the control module is not commanding fan activation.
3. Ignition ON, observe that the fans are not activated.

1. Ignition OFF, disconnect the fan high relay.
2. Ignition ON, observe that both fans are now OFF. If both fans are OFF, replace the fan high relay. If either fan is still activated, remove the fan low relay. If both fans are now OFF replace the fan low relay. If either fan is still activated, test for a short to voltage in the fan voltage supply circuit.

1. Ignition ON, verify with a scan tool that the control module is not commanding fan activation.
2. Ignition ON, observe that the fans are not activated.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the fan low relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the fan low relay, which is fed by the fan 1 fuse. The right fan is connected in series to the left fan through the de-energized series/parallel relay, which is the fan control relay so that both operate at low speed.

In high speed operation, the ECM applies a ground to the coil side of the fan low relay, the fan control relay, and the fan high relay. On the fan high relay, the energized coil closes the switch side of the relay and applies voltage directly to the right cooling fan through the switch side of the relay, which is fed by the fan 2 fuse. At the same time, the ECM energizes fan control relay pulling the switch side over, providing a direct path to ground for the left cooling fan, which has voltage applied through the energized fan low relay. In high speed mode, the fans are operated as a parallel circuit with full voltage applied to each.

Diagnostic Aids

The ECM has the capability of providing command to the fan relays even while a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling Fan Description and Operation

Connector End View Reference

1. «Electrical Center Identification Views»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/electrical-component-locations/#wiring-systems-and-power-management-component-views-2-of-2)
2. «Component Connector End Views»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-starting-point-connector-end-views)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References

1. Verify that the following DTCs are not set: P0480 or P0481. If either of the DTCs is set, repair the DTC first.
2. Ignition ON, command high and low speed fans ON and OFF with a scan tool. Observe to verify that the fans turn ON and OFF when changing between the commanded states.

1. Ignition OFF, disconnect the series/parallel fan relay.
2. Ignition ON, activate the cooling fan relay 1 with a scan tool. The fan should be OFF. If the fan is activated, test the left fan ground circuit for a short to ground.
3. Ignition OFF, disconnect the remaining fan relays.
4. Connect a 30A fused jumper between the normally-open switch contact terminals at the fan control relay connector in order to complete the left fan ground circuit. Leave this jumper in place for the remainder of this procedure.
5. One at a time, connect a 30A fused jumper between the positive terminal at the battery and the fan voltage supply circuit terminal at each relay connection and verify the appropriate fan activation. If the appropriate fan does not activate, test the fan voltage supply circuit for a short to ground or open/high resistance. If the circuit tests normal, test the fan ground circuit for open/high resistance. If the circuits test normal, replace the fan.
6. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the low speed and then the high speed relay connections and verify the appropriate fan activation. If the appropriate fan does not activate, test the relay switch voltage supply circuit for a short to ground or high resistance.
7. If the circuits and fans test normal, replace the relay.

1. «Engine Coolant Fan Motor Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Motor Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)

Ignition ON, command the fan relay ON and OFF with a scan tool. Observe to verify that the appropriate fan turns ON and OFF with each command.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan output control drivers, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on engine cooling requirements. The ECM controls the five relays by grounding the relay control circuits.

During low speed operation, the ECM supplies the ground path for the low fan relay control circuit. This energizes the low fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the de-energized fan control relay, through the right cooling fan in-line resistor, and through the right cooling fan. The result is a series circuit with both fans running at low speed.

During medium speed operation the ECM grounds one control circuit that energizes a bank of three relays consisting of the FAN Mid 1 relay, the fan control relay, and the FAN Mid 2 relay. When these three relays are energized the Mid 1 relay supplies battery voltage to the left cooling fan through the left cooling fan resistor. A ground path is provided for the left fan through the energized fan control relay. At the same time the Mid 2 relay is energized which applies battery voltage to the right cooling fan through the right cooling fan resistor. The result is a parallel circuit where each fan has voltage applied through a resistor which causes each fan to operate at reduced speed.

During high speed operation the ECM grounds all three relay control circuits which activates all five relays. This allows full battery voltage to be applied to the right cooling fan from the high fan relay, and full battery voltage to be applied to the left fan from the low fan relay. The left fan is grounded through the fan control relay. In this arrangement each fan has full battery voltage applied and each fan has its own ground path. The result is a parallel circuit with both fans running at high speed.

When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage.

The ECM has the capability of providing command to the fan relays even while a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Verify that the following DTCs are not set: P0480, P0481, or P0482. If any of the DTCs are set, repair the DTC first.
2. Ignition ON, command high and low speed fans ON and OFF with a scan tool. Observe to verify that the fans turn ON and OFF when changing between the commanded states.

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(ref-317195-S34112436632009060900000) .
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) for DTC P254F.
3. Ignition OFF, disconnect the fan control relay.
4. Ignition ON, activate the low cooling fan using the Relay 1 command on a scan tool. The fan should be OFF. If the fan is activated, test the left fan ground circuit for a short to ground.
5. Ignition OFF, disconnect the remaining fan relays.
6. Connect a 30A fused jumper between the normally-open switch contact terminals at the fan control relay connector in order to complete the left fan ground circuit. Leave this jumper in place for the remainder of this procedure.
7. One at a time, connect a 30A fused jumper between the positive terminal at the battery and the fan voltage supply circuit terminal at each relay connection and verify the appropriate fan activation. If the appropriate fan does not activate, test the fan voltage supply circuit for a short to ground or open/high resistance. If the circuit tests normal, test the fan ground circuit for open/high resistance. If the circuits test normal, replace the fan.
8. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the low speed and then the high speed relay connections and verify the appropriate fan activation. If the appropriate fan does not activate, test the relay switch voltage supply circuit for a short to ground or high resistance.
9. If the circuits and fans test normal, replace the relay.

1. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Underhood Electrical Center or Junction Block Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)

Ignition ON, command the fan relay ON and OFF with a scan tool. Observe to verify that the appropriate fan turns ON and OFF with each command.

Engine Overheating

Loss of Coolant

Tools Required

J 24731 Tempil Stick. See Special Tools .

Use one of the following procedures in testing for a malfunctioning thermostat.

Thermostat Test Procedure Using Tempil Sticks

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a pencil like device. It has a wax material containing certain chemicals which melt at a given temperature. Temperature sticks can be used to determine a thermostat's operating range, by rubbing 87°C (188°F) and 97°C (206°F) sticks on the thermostat housing.

1. Use a tempil stick in order to find the opening and the closing temperatures of the coolant thermostat. J 24731 -188 tempil stick melts at 87°C (188°F). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . The thermostat should begin to open. J 24731 -206 tempil stick melts at 97°C (206°F). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . The thermostat should be fully open.
2. Replace the coolant thermostat if it does not operate properly between this temperature range.

Thermostat Test Procedure Using Glycol

Inspect the operation of the thermostat by hanging the thermostat on a hook in a 50/50 percent solution of DEX-COOL® and clean drinkable water.

In order to inspect if the thermostat valve is opening properly, perform the following test

1. Completely submerge the thermostat in the glycol solution. The solution should be 11°C (22°F) above the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should open.

In order to inspect if the thermostat valve is closing properly, perform the following test

1. Completely submerge the thermostat in a glycol solution. The solution should be 6°C (10°F) below the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should close completely.

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The optional coolant heater operates using 110 volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. There is an internal thermal switch in the power cord that prevents operation above -18°C (0°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

Reference Information

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

1. Test the engine coolant heater for an open or short to ground. If open or shorted, replace the heater.
2. If the heater tests normal, replace the coolant heater power cord.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Coolant Heater Replacement (With LH6, LY2, LGM, LY5 or LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With L76 or L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Coolant Heater Cord Replacement (LH6, LMG, LY2 and LY5)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (L76 and L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The optional coolant heater operates using 110 volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. There are two heater cords available. One has an internal thermal switch in the power cord that prevents operation above -18°C (0°F) and the other operates at all temperatures. A weather shield on the cord is provided to protect the plug when not in use.

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

1. Test the engine coolant heater for an open or short to ground. If open or shorted, replace the heater.
2. If the heater tests normal, replace the coolant heater power cord.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Coolant Heater Replacement (With LH6, LY2, LGM, LY5 or LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With L76 or L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Coolant Heater Cord Replacement (LH6, LMG, LY2 and LY5)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (L76 and L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)

Engine Fails To Reach Normal Operating Temperature

Special Tools

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 42401 Radiator Cap/Surge Tank Test Adapter. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Pressure Cap Testing

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the J 24460-01 (1) with J 42401 (2) in order to test the pressure cap. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Test the pressure cap for the following conditions: Pressure release when the J 24460-01 exceeds the pressure rating of the pressure cap. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . Maintain the rated pressure for at least 10 seconds. Note the rate of pressure loss.
5. Replace the pressure cap under the following conditions: The pressure cap does not release pressure which exceeds the rated pressure of the cap. The pressure cap does not hold the rated pressure.

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 42401 Radiator Cap/Surge Tank Test Adapter. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Test Procedure

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__pressure-cap-testing) .
3. Wash the pressure cap mating surface with water.
4. Use the J 24460-01 with the J 42401 in order to apply pressure to the cooling system. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gage for any pressure loss.
6. Repair any leaks as required.

Fan Clutch Diagnosis

1. GE-47716 Vac-N-Fill Coolant Refill Tool. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 26568 Coolant and Battery Tester. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. J 42401 Radiator Cap and Surge Tank Test Adapter. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Draining Procedure

1. Park the vehicle on a level surface.
2. Remove the coolant pressure cap.
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
4. Place a drain pan under the drain cock and/or lower radiator hose.
5. Reposition the radiator drain cock and/or lower radiator hose.
6. Drain the cooling system.
7. If a complete engine block drain is required, remove the engine block drain plug.
8. Inspect the coolant.
9. Follow the appropriate procedure based on the condition of the coolant. Normal in appearance-Follow the filling procedure. Discolored-Follow the flush procedure. Refer to «Flushing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Vac-N-Fill Procedure

Note. To prevent boiling of the coolant/water mixture in the vehicles cooling system, do not apply vacuum to a cooling system above 49°C (120°F). The tool will not operate properly when the coolant is boiling.

1. Install the J 42401 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Attach the Van-N-Fill cap to the vehicles coolant fill port.
3. Attach the vacuum gage assembly to the Vac-N-Fill cap.
4. Attach the fill hose to the barb fitting on the vacuum gage assembly. Ensure that the valve is closed.
5. Pour the coolant mixture into the graduated reservoir.
6. Place the fill hose in the graduated reservoir.
7. Install the vacuum tank on the graduated reservoir with the fill hose routed through the cut-out area in the vacuum tank.
8. Attach the venture assembly to the vacuum tank.
9. Attach a shop air hose to the venture assembly. Ensure the valve on the venture assembly is closed.
10. Attach the vacuum hose to the vacuum gage assembly and the vacuum tank.
11. Clamp off the overflow hose.
12. Open the valve on the venture assembly. The vacuum gage will begin to rise and a hissing noise will be present.
13. Continue to draw vacuum until the needle stops rising. This should be 610-660 mm Hg (24-26 in Hg). Cooling hoses may start to collapse. This is normal due to vacuum draw.
14. To aid in the fill process, position the graduated reservoir above the coolant fill port.
15. Slowly open the valve on the vacuum gage assembly. When the coolant reaches the top of the fill hose, close the valve. This will eliminate air from the fill hose.
16. Close the valve on the venture assembly.
17. If there is a suspected leak in the cooling system, allow the system to stabilize under vacuum and monitor for vacuum loss. If vacuum loss is observed, refer to «Loss of Coolant»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) .
18. Open the valve on the vacuum gage assembly. The vacuum gage will drop as coolant is drawn into the system.
19. Once the vacuum gage reaches zero, close the valve on the vacuum gage assembly and repeat steps 11-17.
20. Remove the J 42401 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
21. Detach the Vac-N-Fill cap from the vehicles coolant fill port.
22. Add coolant to the system as necessary.
23. Inspect the concentration of the coolant mixture using J 26568 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
24. Detach the vacuum hose form the vacuum gage assembly.
25. Attach the extraction hose to the vacuum hose.
26. Open the valve on the venture assembly to start a vacuum draw.
27. Use the extraction hose to draw out coolant to the proper level.
28. The vacuum tank has a drain valve on the bottom of the tank. Open the valve to drain coolant from the vacuum tank into a suitable container for disposal.

1. J 26568 Coolant and Battery Tester. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 38185 Hose Clamp Pliers. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Follow the steps below in order to remove the surge tank fill cap: Slowly rotate the cap counterclockwise. Stop rotating and allow the hissing to stop. After all the hissing stops, continue turning counterclockwise in order to remove the cap.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
3. Place a drain pan under the lower radiator hose and/or drain cock.
4. Using the J 38185 , reposition the lower radiator hose clamp. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Reposition the lower radiator hose and/or drain cock from the radiator.
6. Drain the cooling system.
7. If a complete engine block drain is required, remove the left and right engine block coolant drain plugs.
8. Remove the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (With LH6, LY2, LGM, LY5 or LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With L76 or L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Inspect the coolant.
10. Follow the appropriate procedure based on the condition of the coolant: Normal in appearance-Follow the filling procedure. Discolored-Follow the flush procedure. Refer to «Flushing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Filling Procedure

1. Install the lower radiator hose and/or drain cock to the radiator.
2. Using the J 38185 , reposition the lower radiator hose clamp. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. If the left and right engine block coolant drain plugs were removed, perform the following: Apply pipe sealer to the drain plugs. Install the drain plugs. Tighten: Tighten the drain plugs to 60 N.m (44 lb ft).
4. Install the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (With LH6, LY2, LGM, LY5 or LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With L76 or L92)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LU3)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Lower the vehicle.
6. Slowly fill the cooling system with a 50/50 coolant mixture. Refer to «Approximate Fluid Capacities»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
7. Install the coolant pressure cap.
8. Start the engine.
9. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature. Engine should reach an operating temperature of 90°C (194°F) and the upper radiator hose should be HOT.
10. Allow the engine to idle for 3 minutes.
11. Shut the engine OFF.
12. Allow the engine to cool.
13. Top off the coolant as necessary.
14. Inspect the concentration of the engine coolant using the J 26568 . See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
15. Rinse away any excess coolant from the engine and the engine compartment.

Flushing

Radiator Cleaning

1. Some conditions may require the use of warm water and a mild detergent.
2. Clean the A/C condenser fins.
3. Clean between the A/C condenser and radiator.
4. Clean the radiator cooling fins.
5. Straighten any damaged cooling fins.

Scheme 4

Scheme 5

Removal Procedure

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the surge tank inlet hose clamp from the radiator.
3. Remove the surge tank inlet hose from the radiator.
4. Reposition the surge tank inlet hose clamp at the surge tank.
5. Remove the surge tank inlet hose (1) from the surge tank.

Installation Procedure

1. Install the surge tank inlet hose (1) to the surge tank.
2. Position the surge tank inlet hose clamp to the surge tank.
3. Install the surge tank inlet hose to the radiator.
4. Position the surge tank inlet hose clamp to the radiator.
5. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 6

Scheme 7

1. Drain the engine coolant. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Move the hose clamps back on the radiator inlet hose.
3. Remove the radiator inlet hose from the radiator.
4. Remove the radiator inlet hose from the water outlet tube.

1. Install the radiator inlet hose to the water outlet tube.
2. Install the radiator inlet hose to the radiator.
3. Install the hose clamps on the radiator outlet hose.
4. Fill the engine coolant. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 8

1. Drain the engine coolant. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the upper and lower fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) and «Engine Coolant Fan Lower Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the surge tank outlet hose (1) from the surge tank.
4. Remove the radiator outlet hose from the water pump.
5. Remove the heater outlet hose from the radiator outlet hose.
6. Remove the radiator outlet hose from the radiator.
7. Remove the radiator outlet hose clip retainers from the brackets.
8. Remove the radiator outlet hose from the vehicle.

1. Install the radiator outlet hose to the vehicle.
2. Install the radiator outlet hose and clamp to the radiator. Ensure the hose is positioned properly in order to prevent interference with the fan shroud.
3. Install the radiator outlet hose clip retainers to the brackets.
4. Install the surge tank outlet hose (1) to the surge tank.
5. Install the radiator outlet hose and clamp to the water pump.
6. Install the heater outlet hose to the radiator outlet hose.
7. Install the upper and lower fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) and «Engine Coolant Fan Lower Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Fill the engine coolant. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 9

Scheme 10

1. Using a bent-tip screwdriver or equivalent, pull on one of the open ends of the retaining ring in order to rotate the retaining ring.
2. Rotate the retaining ring (3) around the quick connector until the retaining ring is out of position and can be completely removed.
3. Remove the radiator outlet hose (2) from the quick connector fitting at the radiator (1).

1. Hook one of the open ends of the retaining ring (3) in one of the slots in the quick connector.
2. Rotate the retaining ring (3) around the connector until the retaining ring is positioned with all 3 ears through the 3 slots.
3. Ensure the 3 retaining ring ears can be seen from the inside of the connector and the retaining ring can move freely in the slots.
4. Install the radiator outlet hose (2) onto the radiator quick connector fitting until a click is heard or felt. Pull back on the radiator outlet hose (2) to ensure a proper connection.

Scheme 11

Scheme 12

Scheme 13

1. Disengage the plastic caps from the quick connect fittings. Pull the caps back along the pipe.
2. Using a bent-tip screwdriver or equivalent, pull on one of the open ends of the retaining ring in order to rotate the retaining ring.
3. Rotate the retaining ring around the quick connector until the retaining ring is out of position and can be completely removed. Discard the retaining rings.
4. Remove the engine oil cooler line from the quick connector fitting at the radiator. Refer to «Engine Oil Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . Pull the lines straight out from the connectors.
5. Clean all of the components in a suitable solvent, and dry them with compressed air.
6. Inspect the fittings, the connectors, the cooler lines, and the cooler for damage, distortion, or restriction. Replace parts as necessary.

1. Install a new retaining ring into each quick connector fitting.
2. Hook one of the open ends of the retaining ring in one of the slots in the quick connector.
3. Rotate the retaining ring around the connector until the retaining ring is positioned with all 3 ears through the 3 slots.
4. Ensure the 3 retaining ring ears can be seen from the inside of the connector and the retaining ring can move freely in the slots.
5. Install the engine oil cooler line into the quick connector fitting until a click is heard or felt. Pull back on the engine oil cooler lines to ensure a proper connection.
6. Snap the plastic cap onto the quick connect fitting.
7. Ensure that the plastic cap is fully seated against the fitting.
8. Ensure that no gap is present between the cap and the fitting.
9. Inspect and fill the engine oil to the proper level.

1. DT-47731 1/2 in Line Quick Release Tool
2. J 28585 Universal Snap Ring Remover for the 5/8 in Line

1. Remove the plastic caps from the quick connect fittings by pulling the caps back along the pipe before installation.
2. Install the DT-47731 onto the engine oil cooler (EOC) pipe, or use the J 28585
3. Slide the DT-47731 toward the EOC pipe fitting, or use the J 28585
4. Connect the DT-47731 onto the EOC pipe fitting.
5. Rotate the DT-47731 or use the J 28585 until the retainer clip (1) rises above the fitting retainer seat.
6. Pull back on the EOC pipe to disengage the pipe from the EOC pipe fitting.
7. Remove the DT-47731 or the J 28585 from the EOC pipe.

1. Install the EOC pipe into the EOC pipe fitting. A distinct snap should be heard or felt when assembling the EOC pipe to the fitting.
2. To ensure the cooler line is properly installed, give the cooler pipe a gentle pull.

The optional oil cooler is either an integral part of the radiator or a separate unit placed in front of the radiator. The cooler lines and hoses are serviceable.

1. Disconnect the engine oil cooler quick connect fittings. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. If equipped with regular production option (RPO) L76 (6.0L) engine, perform the following. Open the oil cooler hose clip located on the lower fan shroud. Remove the oil cooler hoses from the clip.
3. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
4. If equipped with RPO LY6 (6.0L) engine, remove the oil cooler hoses from the clip.
5. Place a jack or utility stands at the rear of the vehicle.
6. If equipped, remove the engine protection shield. Refer to «Engine Shield Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .
7. For both 1500 and 2500 series, support the front differential carrier with a suitable adjustable jack.
8. For 1500 series vehicles, remove the differential carrier right side nuts.
9. Remove the differential carrier left side bolts.
10. Lower the differential carrier.
11. For 2500 series vehicles, remove the differential carrier right side nuts.
12. Remove the differential carrier upper mounting bolt and nut.
13. Remove the differential carrier lower mounting bolt and nut.
14. If equipped with RPO L76 (6.0L) engine, perform the following: Lower the differential carrier. Remove the oil cooler hose adapter bolts (2). Remove the oil cooler hose assembly and gasket. Discard the gasket. Inspect the fittings, connectors, and cooler hoses for damage or distortion.
15. If equipped with RPO LY6 (6.0L) engine, perform the following: Remove the oil cooler hose bracket bolt. (1) Remove the oil cooler hose adapter bolts. (2) Remove the oil cooler hose assembly. Discard the gasket. Inspect the fittings, connectors, and cooler hoses for damage or distortion.

1. If equipped with RPO LY6 (6.0L) engine, perform the following: Install the oil cooler hose assembly and a NEW gasket. Install the oil cooler hose adapter bolts (2). Tighten: Tighten the bolts to 12 N.m (106 lb in). Install the oil cooler hose bracket bolt. Tighten: Tighten the bolt to 25 N.m (18 lb ft).
2. If equipped with a RPO L76 (6.0L) engine, perform the following. Install the oil cooler hose assembly and a NEW gasket. Install the oil cooler hose adapter bolts (2). Tighten: Tighten the bolts to 12 N.m (106 lb in). Install the oil cooler hose bracket bolt (1). Tighten: Tighten the bolt to 25 N.m (18 lb ft).
3. For 2500 series vehicles, raise the differential carrier into position.
4. Install the differential carrier left side upper bolt and nut until snug.
5. Install the differential carrier left side lower bolt and nut until snug.
6. Install the differential carrier right side nuts. Tighten: Tighten the bolt to 100 N.m (74 lb ft).
7. For 1500 series vehicles, raise the differential carrier into position.
8. Install the differential carrier right side nuts.
9. Install the differential carrier left side bolts. Tighten: Tighten the bolts/nuts to 100 N.m (74 lb ft).
10. If equipped, install the engine protection shield. Refer to «Engine Shield Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .
11. Remove the jack or utility stand from the rear of the vehicle.
12. Lower the vehicle.
13. If equipped with RPO LY6 (6.0L) engine, install the oil cooler hoses to the clip.
14. If equipped with RPO L76 (6.0L) engine, perform the following: Install the oil cooler hoses to the hose clip on the fan shroud. Snap the oil cooler hose clip shut.
15. Install the oil cooler lines to the radiator. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. J 41240-5A Fan Clutch Wrench. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J-48460 Fan Clutch Remover and Installer Kit. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Install the J-48460 Fan Clutch Remover and Installer Kit (1). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Install the J 41240-5A Fan Clutch Wrench (2). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the fan hub nut from the water pump in a counterclockwise rotation.
5. Remove the fan clutch bolts from the rear of the fan blade.
6. Separate the fan clutch from the fan blade.

1. Install the fan clutch onto the fan blade.
2. Install the fan clutch bolts. Tighten: Tighten the bolts to 23 N.m (17 lb ft).
3. Install the fan assembly.
4. Install the J-48460 Fan Clutch Remover and Installer Kit (1) and J 41240-5A Fan Clutch wrench (2). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . Tighten: Tighten the nut clockwise to 56 N.m (41 lb ft).
5. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

J 46406 Fan Clutch Remover and Installer. See Special Tools .

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the 3 engine cooling fan shroud bolts (1).
3. Position the engine cooling fan shroud (1) forward to the radiator.
4. Install a long pin bar into the fan hub (1).
5. Use a J 46406 to remove the fan hub nut (2) from the hub in a counterclockwise rotation. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Remove the fan and the engine cooling fan shroud as an assembly.
7. Separate fan and shroud.
8. Remove the fan clutch bolts from the rear of the fan blade.
9. Separate the fan clutch from the fan blade.

1. Install the fan clutch onto the fan blade.
2. Install the fan clutch bolts Tighten: Tighten the bolts to 23 N.m (17 lb ft).
3. Install the fan and engine cooling fan shroud assembly to the fan hub.
4. Use a J 46406 on the fan clutch hub nut (2) to install a long pry bar to the fan clutch hub (1). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . Tighten: Tighten the nut clockwise to 56 N.m (41 lb ft).
5. Position the engine cooling fan shroud on the 3 mounting brackets (1).
6. Install the bolts. Loosely tighten the top mounting bolt at the oil filler neck.
7. Center the engine cooling fan shroud to the fan blade in 3 places (1).
8. Make sure the orientation of the cooling fan shroud (1) and rubber seal (2) are installed correctly
9. Fully tighten the 3 engine cooling fan shroud bolts (1). Tighten: Tighten the bolts to 8 N.m (71 lb in).
10. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

J 41240-5A Fan Clutch Wrench. See Special Tools .

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the 3 engine cooling fan shroud bolts (1).
3. Position the engine cooling fan shroud (1) forward to the radiator.
4. Install a long pin bar into the fan hub (1).
5. Use a J 41240-5A to remove the fan hub nut (2) from the hub in a counterclockwise rotation. See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Remove the fan and the engine cooling fan shroud as an assembly.
7. Remove the fan clutch bolts from the rear of the fan blade.
8. Separate the fan clutch from the fan blade.

1. Install the fan clutch onto the fan blade.
2. Install the fan clutch bolts. Tighten: Tighten the bolts to 23 N.m (17 lb ft).
3. Install the fan and engine cooling fan shroud assembly to the fan hub.
4. Use a J 41240-5A on the fan clutch hub nut (2) to install a long pry bar to the fan clutch hub (1). See «Special Tools»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) . Tighten: Tighten the nut clockwise to 56 N.m (41 lb ft).
5. Position the engine cooling fan shroud on the 3 mounting brackets (1).
6. Install the bolts. Loosely tighten the top mounting bolt at the oil filler neck.
7. Center the engine cooling fan shroud to the fan blade in 3 places (1).
8. Make sure the orientation of the cooling fan shroud (1) and rubber seal (2) are installed correctly
9. Fully tighten the 3 engine cooling fan shroud bolts (1). Tighten: Tighten the bolts to 8 N.m (71 lb in).
10. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (LMM Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the drive belt. Refer to «Drive Belt Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
2. Remove the fan clutch. Refer to «Fan Clutch Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Disconnect the camshaft position (CMP) sensor electrical connector.
4. Remove the fan pulley bolts/nuts.
5. Remove the fan pulley.

1. Install the fan pulley.
2. Install the fan pulley bolts/nuts. Tighten: Tighten the bolts/nuts to 41 N.m (30 lb ft).
3. Connect the CMP sensor electrical connector.
4. Install the fan clutch. Refer to «Fan Clutch Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Install the drive belt. Refer to «Drive Belt Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .

1. Remove the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan and Shroud Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the cooling fan blade retainers.
3. Remove the cooling fan blades.

1. Install the cooling fan blades.
2. Install the cooling fan blade retainers.
3. Install the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan and Shroud Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 14

1. Remove the cooling blade(s). Refer to «Engine Coolant Fan Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the cooling fan motor bolts.
3. Remove the cooling fan motor(s).

1. Install the cooling fan motor(s).
2. Install the cooling fan motor bolts. Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Install the cooling fan blades. Refer to «Engine Coolant Fan Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 15

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
2. Remove air inlet duct.
3. Disconnect upper radiator hose from radiator.
4. Disengage the radiator inlet hose clip (2) at the fan shroud.
5. If necessary, reposition the surge tank inlet hose clamp at the radiator.
6. If necessary, remove the surge tank inlet hose from the radiator.
7. Disconnect the electrical connectors from the cooling fans.
8. Remove the clip attaching the wiring harness to the shroud.
9. Remove transmission cooler lines bolts from fan shroud.
10. If necessary, open the engine oil cooler line clip and remove the cooler lines from the clip.
11. Remove the cooling fan shroud bolts.
12. Remove the cooling fan and shroud.

1. Install the cooling fan and shroud.
2. Install the cooling fan shroud bolts. Tighten: Tighten the bolts to 9 N.m (80 lb in).
3. If equipped, install the cooler lines to the clip and close the clip.
4. Connect the electrical connectors to the cooling fans.
5. Install the clip attaching the wiring harness to the shroud.
6. Install the transmission cooling line bolts to fan shroud. Tighten: Tighten the bolts to 4 N.m (35 lb in).
7. If necessary, install the surge tank inlet hose to the radiator.
8. If necessary, reposition the surge tank inlet hose clamp at the radiator.
9. Engage the radiator inlet hose clip (2) at the fan shroud.
10. Connect upper radiator hose from radiator.
11. Install air inlet duct.
12. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)

Scheme 16

Scheme 17

Scheme 18

1. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the coolant inlet hose clamp.
4. Disconnect the turbocharger coolant inlet hose from the turbocharger bypass valve.
5. Remove the turbocharger bypass valve and washer.

1. Install the turbocharger bypass valve and washer. Tighten: Tighten the valve to 60 N.m (44 lb ft).
2. Connect the turbocharger coolant inlet hose to the turbocharger bypass valve.
3. Position the coolant inlet hose clamp.
4. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .

1. Remove the turbocharger coolant inlet pipe. Refer to «Turbocharger Coolant Hoses/Pipes Replacement (LMM Outlet Pipe)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the generator mounting bracket. Refer to «Generator Bracket Replacement (6.6L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) .
3. Remove the exhaust gas recirculation (EGR) cooler assembly. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
4. Remove the cooling fan clutch. Refer to «Fan Clutch Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Reposition the hose clamp at the bypass pipe.
6. Remove the turbocharger coolant outlet hose from the bypass pipe.
7. Reposition the turbocharger coolant outlet hose clamp.
8. Remove the turbocharger coolant outlet hose from the pipe on the turbocharger.
9. Remove the turbocharger coolant outlet pipe bolt and nut.
10. If necessary, remove the turbocharger. Refer to «Turbocharger Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
11. If necessary, remove the coolant outlet pipe clip bolt (3) from the turbocharger.
12. If necessary, remove the coolant outlet pipe.

1. If necessary, install the coolant outlet pipe.
2. If necessary, install the coolant outlet pipe clip bolt (3) to the turbocharger. Tighten: Tighten the bolt to 9 N.m (80 lb in).
3. If necessary, install the turbocharger. Refer to «Turbocharger Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
4. Install the turbocharger coolant outlet pipe bolt and nut. Tighten: Tighten the bolt/nut to 9 N.m (80 lb in).
5. Install the turbocharger coolant outlet hose to the pipe on the turbocharger.
6. Position the turbocharger coolant outlet hose clamp.
7. Install the turbocharger coolant outlet hose to the bypass pipe.
8. Position the hose clamp at the bypass pipe.
9. Install the cooling fan clutch. Refer to «Fan Clutch Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
10. Install the EGR cooler assembly. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
11. Install the generator mounting bracket. Refer to «Generator Bracket Replacement (6.6L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) .
12. Install the turbocharger coolant inlet pipe. Refer to «Turbocharger Coolant Hoses/Pipes Replacement (LMM Outlet Pipe)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

J 38185 Hose Clamp Pliers. See Special Tools .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the EGR cooler pipe clamp (1) and remove the EGR cooler pipe hose from the EGR cooler tube.
3. Remove the upper EGR cooler pipe nut (1).
4. Remove the lower EGR cooler pipe bolt (1).
5. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
6. Remove the EGR cooler pipe bolt (1) and bracket (2).
7. Remove the EGR cooler pipe from the engine.

1. Position the EGR cooler pipe to the engine.
2. Install the EGR cooler pipe bracket (2) and bolt (1). Tighten: Tighten the bolt to 9 N.m (80 lb in).
3. Lower the vehicle.
4. Install the lower EGR cooler pipe bolt (1).
5. Install the upper EGR cooler pipe nut (1). Tighten: Tighten the bolt to 9 N.m (80 lb in).
6. Install the EGR cooler pipe hose to the EGR cooler tube and reposition the EGR cooler pipe clamp (1).
7. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

J 38185 Hose Clamp Pliers. See Special Tools .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the EGR cooler pipe clamp (1) and remove the EGR cooler pipe hose from the EGR cooler tube.
3. Remove the upper EGR cooler pipe nut (1).
4. Remove the lower EGR cooler pipe bolt (1).
5. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
6. Remove the EGR cooler pipe bolt (1) and bracket (2).
7. Remove the EGR cooler pipe from the engine.

1. Position the EGR cooler pipe to the engine.
2. Install the EGR cooler pipe bracket (2) and bolt (1). Tighten: Tighten the bolt to 9 N.m (80 lb in).
3. Lower the vehicle.
4. Install the lower EGR cooler pipe bolt (1).
5. Install the upper EGR cooler pipe nut (1). Tighten: Tighten the bolt to 9 N.m (80 lb in).
6. Install the EGR cooler pipe hose to the EGR cooler tube and reposition the EGR cooler pipe clamp (1).
7. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the air cleaner outlet resonator duct. Refer to «Air Cleaner Outlet Resonator Replacement»(ref-317159-S07572633432009060900000) .
2. Remove the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the turbocharger coolant bypass valve. Refer to «Turbocharger Coolant Bypass Valve Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the water outlet bolts.
5. Remove the water outlet.
6. Remove and discard the gasket.

1. Install a NEW gasket to the water outlet.
2. Lubricate the O-ring seal with clean engine coolant.
3. Install the water outlet.
4. Install the water outlet bolts. Tighten: Tighten the bolts to 21 N.m (15 lb ft).
5. Install the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Install the air cleaner outlet resonator duct. Refer to «Air Cleaner Outlet Resonator Replacement»(ref-317159-S07572633432009060900000) .

1. Remove the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the turbocharger coolant bypass valve. Refer to «Turbocharger Coolant Bypass Valve Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the bolts and wiring harness bracket at the thermostat housing.
4. Position the bracket and wiring harness aside.
5. Disconnect the main engine electrical harness connectors. Lift up on the latches (1) in order to disconnect the connectors.
6. Open the harness clip (2).
7. Remove the main engine electrical harness connectors.
8. Disconnect the turbocharger vane position sensor electrical connector (1).
9. Unclip the main engine electrical harness connectors from the main electrical connector harness bracket.
10. Remove the main electrical connector harness bracket bolts (1).
11. Remove the main electrical connector harness bracket (2) and position aside.
12. Remove the manifold intake temperature sensor electrical connector from the water tube bracket.
13. Remove the water outlet bolts.
14. Remove the water outlet.
15. Remove and discard the O-ring seal.

1. Install a NEW O-ring seal to the water outlet.
2. Lubricate the O-ring seal with clean engine coolant.
3. Install the water outlet.
4. Install the water outlet bolts. Tighten: Tighten the bolts to 21 N.m (15 lb ft).
5. Install the manifold intake temperature sensor electrical connector to the water tube bracket.
6. Install the main electrical harness bracket.
7. Install the main electrical harness bracket bolts. Tighten: Tighten the bolts to 21 N.m (15 lb ft).
8. Install the main engine electrical harness connector bolts. Tighten: Tighten the bolts to 10 N.m (89 lb in).
9. Install the main electrical connector harness bracket (2).
10. Install the main electrical connector harness bracket bolts (1). Tighten: Tighten the bolts to 21 N.m (15 lb ft).
11. Clip the main engine electrical harness connectors to the main electrical connector harness bracket.
12. Connect the turbocharger vane position sensor electrical connector (1).
13. Connect the main engine electrical harness connectors.
14. Push down on the latches (1) in order to connect the connectors.
15. Close the harness clip (2).
16. Install the wiring harness bracket and bolts to the thermostat housing. Tighten: Tighten the bolts to 10 N.m (89 lb in).
17. Install the turbocharger coolant bypass valve. Refer to «Turbocharger Coolant Bypass Valve Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
18. Install the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
3. Reposition the radiator outlet hose clamp at the water pump inlet.
4. Remove the radiator outlet hose from the water pump inlet.
5. Remove the water pump inlet bolts.
6. Remove the water pump inlet from the water pump.
7. Remove and discard the water pump inlet seal.

1. Install a NEW water pump inlet seal to the water pump inlet.
2. Position the water pump inlet to the water pump.
3. Install the water pump inlet bolts. Tighten: Tighten the bolts to 15 N.m (11 lb ft).
4. Install the radiator outlet hose to the water pump inlet.
5. Position the radiator outlet hose clamp at the water pump inlet.
6. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
7. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the thermostat housing. Refer to «Engine Coolant Thermostat Housing Replacement (LFA,LH6, LMG,LY2, LY5,LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the thermostat.

1. Install the thermostat.
2. Install the thermostat housing. Refer to «Engine Coolant Thermostat Housing Replacement (LFA,LH6, LMG,LY2, LY5,LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the air cleaner. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Disconnect the negative battery cables. Refer to «Battery Negative Cable Disconnection and Connection (With Single Battery)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) or «Battery Negative Cable Disconnection and Connection (With Auxiliary Battery)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) or «Battery Negative Cable Disconnection and Connection (With Dual Batteries)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) .
4. Remove the drive belt. Refer to «Drive Belt Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
5. Disconnect the air conditioning (A/C) pressure switch electrical connector (1).
6. Disconnect the A/C compressor clutch electrical connector (2).
7. Remove the generator bracket. Refer to «Generator Bracket Replacement (6.6L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) .
8. Remove the front oil fill tube. Refer to «Oil Filler Tube Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
9. Disconnect the engine coolant temperature (ECT) sensor electrical connectors.
10. Remove the water outlet. Refer to «Water Outlet Tube Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
11. Without disconnecting the power steering hoses, remove the power steering pump bolts and the power steering pump. Reposition the power steering pump and secure to the side. Refer to «Power Steering Pump Replacement (6.6L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/manual-power-steering/#power-steering-system) .
12. Remove the power steering pump bracket. Refer to «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
13. Remove the bolts and wiring harness bracket at the thermostat housing.
14. Position the bracket and wiring harness aside.
15. Remove the cooling fan pulley. Refer to «Fan Pulley Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
16. Reposition the turbocharger coolant return pipe hose clamp.
17. Remove the turbocharger coolant return pipe hose.
18. Remove the fuel line bracket bolt at the thermostat housing crossover.
19. Remove the water pump inlet pipe bolts.
20. Remove the thermostat housing crossover bolts and nuts.
21. Remove the thermostat housing crossover, with the bypass pipe.
22. Remove and discard the thermostat bypass pipe to water pump O-ring seal.
23. Remove and discard the thermostat housing crossover gaskets.
24. If necessary, perform the following: Remove the thermostat bypass pipe from the thermostat housing crossover. Remove and discard the thermostat bypass pipe O-ring seal. Remove the thermostat cover bolts and cover. Remove the thermostats. Remove and discard the thermostat seals.
25. If required, clean and inspect the thermostat housing. Refer to «Engine Coolant Thermostat Housing Cleaning and Inspection»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-4-of-5__engine-coolant-thermostat-housing-cleaning-and) .

1. If necessary, perform the following: Install NEW seals to the thermostats. Install the thermostats. Install the thermostat cover and bolts. Tighten: Tighten the bolts to 21 N.m (15 lb ft). Install a NEW O-ring seal to the thermostat bypass pipe. Install the thermostat bypass pipe to the thermostat housing.
2. Install a NEW thermostat bypass pipe to water pump O-ring seal.
3. Install the thermostat housing crossover using NEW gaskets.
4. Install the thermostat housing crossover bolts and nuts. Tighten: Tighten the bolts/nuts to 21 N.m (15 lb ft).
5. Install the water pump inlet pipe bolts. Tighten: Tighten the bolts to 21 N.m (15 lb ft).
6. Install the fuel line bracket bolt at the thermostat housing crossover. Tighten: Tighten the bolt to 21 N.m (15 lb ft).
7. Install the turbocharger coolant return pipe hose.
8. Position the turbocharger coolant return pipe hose clamp.
9. Install the wiring harness bracket and bolts to the thermostat housing. Tighten: Tighten the bolts to 10 N.m (89 lb in).
10. Install the cooling fan pulley. Refer to «Fan Pulley Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
11. Install the power steering pump bracket. Refer to «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
12. Reposition the power steering pump and install the power steering pump bolts. Refer to «Power Steering Pump Replacement (6.6L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/manual-power-steering/#power-steering-system) .
13. Install the water outlet. Refer to «Water Outlet Tube Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
14. Connect the ECT sensor electrical connectors.
15. Install the front oil fill tube. Refer to «Oil Filler Tube Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
16. Install the generator bracket. Refer to «Generator Bracket Replacement (6.6L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) .
17. Connect the A/C compressor clutch electrical connector (2).
18. Connect the A/C cut out switch electrical connector (1).
19. Install the drive belt. Refer to «Drive Belt Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
20. Connect the negative battery cables. Refer to «Battery Negative Cable Disconnection and Connection (With Single Battery)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) or «Battery Negative Cable Disconnection and Connection (With Auxiliary Battery)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) or «Battery Negative Cable Disconnection and Connection (With Dual Batteries)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/charging-system/#battery-charging-system-starting-system) .
21. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
22. Install the air cleaner. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-66l-introduction-1-of-2) .

Scheme 19

1. Drain the cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the fan pulley. Refer to «Fan Pulley Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove Thermostat Bypass Pipe Bolts. 21 N.m (16 lb ft).
4. Thermostat Bypass Pipe to Turbocharger Outlet Cooler Pipe Clamp. Procedure Reposition the thermostat bypass pipe to turbocharger outlet cooler pipe clamp using the BO-38185 Hose Clamp Pliers. Replace hose clamp if necessary.
5. Thermostat Bypass Pipe Tip: Install new O-ring seals. Lubricate using clean engine coolant.

1. If replacing the rear coolant air bleed covers, remove the intake manifold. Refer to «Intake Manifold Replacement (LY2 and LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) . Otherwise proceed to the next step.
2. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
3. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
5. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
6. Remove the coolant air bleed pipe bolts (309) (intake manifold shown removed for clarity).
7. Remove the coolant air bleed pipe (307) and seals (308).
8. Remove the coolant air bleed cover bolts (312), if required.
9. Remove the coolant air bleed covers (313) and seals (308), if required.
10. Remove the seals (308) from the coolant air bleed pipe and/or covers.
11. Discard the seals.

1. Install the seals onto the coolant air bleed pipe and/or covers.
2. Install the coolant air bleed pipe (307) and seals (308) onto the cylinder heads.
3. Install the coolant air bleed pipe bolts (309). Tighten: Tighten the bolts to 12 N.m (106 lb in).
4. Install the coolant air bleed covers (313) and seals (308), if required.
5. Install the coolant air bleed cover bolts (312), if required. Tighten: Tighten the bolts to 12 N.m (106 lb in).
6. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
7. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
8. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
10. If the rear coolant air bleed covers were replaced, install the intake manifold. Refer to «Intake Manifold Replacement (LY2 and LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
4. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
5. Remove the coolant air bleed pipe bolts (309) (intake manifold shown removed for clarity).
6. Remove the coolant air bleed pipe (307) and seals (308).
7. Remove the coolant air bleed cover bolts (312), if required.
8. Discard the seals.

1. Install the seals onto the coolant air bleed pipe and/or covers.
2. Install the coolant air bleed pipe (307) and seals (308) onto the cylinder heads.
3. Install the coolant air bleed pipe bolts (309). Tighten: Tighten the bolts to 12 N.m (106 lb in).
4. Install the coolant air bleed covers (313) and seals (308), if required.
5. Install the coolant air bleed cover bolts (312), if required. Tighten: Tighten the bolts to 12 N.m (106 lb in).
6. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
7. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
8. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
10. If the rear coolant air bleed covers were replaced, install the intake manifold. Refer to «Intake Manifold Replacement (Except LH6, LMG, LY5, L76, LY2, LY6)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) or «Intake Manifold Replacement (LH6, LMG, LY5 and L76)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .

J 41240 Fan Clutch Remover and Installer

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Resonator Replacement»(ref-317159-S07572633432009060900000) .
2. Remove the drive belt. Refer to «Drive Belt Replacement»(ref-317247-S12080742082009060900000) .
3. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Reposition the radiator outlet hose clamps at the surge tank and water pump.
5. Remove the radiator outlet hose from the surge tank.
6. Remove the radiator outlet hose from the water pump.
7. Reposition the water pump inlet hose clamps.
8. Remove the water pump inlet hose.
9. Using J 41240 , hold the water pump pulley, remove the water pump pulley bolts.
10. Remove the water pump bolts.
11. Remove the water pump.
12. Remove and discard the water pump gaskets.
13. Clean and inspect the water pump, if necessary. Refer to «Water Pump Cleaning and Inspection»(ref-317247-S13947163982009060900000) .

1. If reusing the old fasteners, apply sealant GM P/N 12346004, (Canadian P/N 10953480), or equivalent to the threads of the water pump bolts.
2. Install NEW water pump gaskets and the water pump.
3. Install the water pump bolts. Tighten: Tighten the bolts to 45 N.m (33 lb ft).
4. Using J 41240 , hold the water pump pulley, install the water pump pulley bolts. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
5. Install the water pump inlet hose.
6. Position the water pump inlet hose clamps.
7. Install the radiator outlet hose to the water pump.
8. Install the radiator outlet hose to the surge tank.
9. Position the radiator outlet hose clamps at the surge tank and water pump.
10. Install the drive belt. Refer to «Drive Belt Replacement»(ref-317247-S12080742082009060900000) .
11. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Resonator Replacement»(ref-317159-S07572633432009060900000) .
12. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
13. Inspect the cooling system for leaks.

Scheme 20

1. Remove the left wheelhouse inner panel. Refer to «FRONT WHEELHOUSE LINER REPLACEMENT - LEFT SIDE (CHEVROLET)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «FRONT WHEELHOUSE LINER REPLACEMENT - LEFT SIDE (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .
2. Remove the radiator outlet hose. Refer to «Radiator Outlet Hose Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
3. Remove the thermostat bypass pipe. Refer to «Thermostat Bypass Pipe Replacement Diesel.»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
4. Remove the crankshaft balancer. Refer to «CRANKSHAFT BALANCER REPLACEMENT»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
5. Remove the water pump to engine coolant pipe nuts (2) from the studs (1).
6. Remove the engine wiring harness retainer from the inner stud.
7. Remove the water pump bolts. Note the location of the bolts. The bolts are three different lengths.
8. Remove the water pump.
9. Remove and discard the water pump O-ring and coolant pipe gasket.
10. If required, clean and inspect the water pump.

Scheme 21

1. Lubricate the water pump O-ring (3) with engine oil
2. Install the engine coolant pipe gasket and water pump O-ring.
3. Install the water pump nut (1) and bolts (2). Ensure the correct length bolt is used in the proper location and tighten to 25 N.m (18 lb ft) NOTE: Refer to Fastener Notice.
4. Install the engine wiring harness retainer on the water pump outlet pipe inner stud.
5. Install the water pump to water pump outlet pipe nuts (2) to the studs (1) and tighten to 25 N.m (18 lb ft)
6. Install the crankshaft balancer. Refer to «CRANKSHAFT BALANCER REPLACEMENT»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
7. Install the thermostat bypass pipe. Refer to «Thermostat Bypass Pipe Replacement Diesel.»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system)
8. Install the radiator outlet hose. Refer to «Radiator Outlet Hose Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Install the left wheelhouse inner panel. Refer to «FRONT WHEELHOUSE LINER REPLACEMENT - LEFT SIDE (CHEVROLET)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) or «FRONT WHEELHOUSE LINER REPLACEMENT - LEFT SIDE (GMC)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/frames-subframes-crossmembers/#frame-and-underbody) .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
4. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
5. Reposition the radiator inlet hose clamp (3) at the water pump.
6. Remove the radiator inlet hose from the water pump.
7. Reposition the radiator inlet hose and vent inlet hose out of the way.
8. Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .
9. Reposition the radiator outlet hose clamp at the water pump.
10. Remove the radiator outlet hose from the water pump.
11. Reposition the outlet hose out of the way.
12. Reposition the radiator surge tank outlet hose clamp (1) at the water pump.
13. Remove the radiator surge tank outlet hose (2) from the water pump.
14. Reposition the outlet hose out of the way.
15. Reposition the heater inlet hose clamp (1) at the water pump.
16. Remove the heater inlet hose (2) from the water pump.
17. Reposition the inlet hose out of the way.
18. Remove the water pump bolts (301).
19. Remove the water pump (300) and gaskets (309). Discard the gaskets.

Note. All gaskets surfaces are to be free of oil or other foreign material during assembly.

1. Position the water pump (300) and NEW gaskets (306) to the engine block.
2. Install the water pump bolts (301). Tighten: Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the bolts a final pass to 30 N.m (22 lb ft).
3. Position and install the heater inlet hose (2) to the water pump.
4. Position the heater inlet hose clamp (1) at the water pump.
5. Position and install the radiator surge tank outlet hose (2) to the water pump.
6. Position the radiator surge tank outlet hose clamp (1) at the water pump.
7. Position and install the radiator outlet hose to the water pump.
8. Position the radiator outlet hose clamp at the water pump.
9. Install the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .
10. Position the radiator inlet hose and vent inlet hose to the correct position.
11. Install the radiator inlet hose to the water pump.
12. Position the radiator inlet hose clamp (3) at the water pump.
13. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
14. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
15. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
16. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
4. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
5. Reposition the radiator inlet hose clamp (3) at the water pump.
6. Remove the radiator inlet hose from the water pump.
7. Reposition the radiator inlet hose and vent inlet hose out of the way.
8. Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .
9. Reposition the radiator outlet hose clamp at the water pump.
10. Remove the radiator outlet hose from the water pump.
11. Reposition the outlet hose out of the way.
12. Reposition the radiator surge tank outlet hose clamp at the water pump (1).
13. Remove the radiator surge tank outlet hose (2) from the water pump.
14. Reposition the outlet hose out of the way.
15. Reposition the heater inlet hose clamp (1) at the water pump.
16. Remove the heater inlet hose (2) from the water pump.
17. Reposition the inlet hose out of the way.
18. Remove the water pump bolts (301).
19. Remove the water pump (300) and gaskets (309). Discard the gaskets.

Note. All gaskets surfaces are to be free of oil or other foreign material during assembly.

1. Inspect the drained coolant for sand or other debris, flush the system as needed. Refer to «Flushing»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .
2. Inspect and clear the radiator vent hose fitting, if necessary. There is a small 2.0 mm (0.080 in) orifice (vent hose fitting) in the neck of the radiator where the coolant vent hose from the engine attaches to the radiator.
3. Position the water pump (300) and NEW gaskets (306) to the engine block.
4. Install the water pump bolts (301). Tighten: Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the bolts a final pass to 30 N.m (22 lb ft).
5. Position and install the heater inlet hose (2) to the water pump.
6. Position the heater inlet hose clamp (1) at the water pump.
7. Position and install the radiator surge tank outlet hose (2) to the water pump.
8. Position the radiator surge tank outlet hose clamp at the water pump (1).
9. Position and install the radiator outlet hose to the water pump.
10. Position the radiator outlet hose clamp at the water pump.
11. Install the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .
12. Position the radiator inlet hose and vent inlet hose to the correct position.
13. Install the radiator inlet hose to the water pump.
14. Position the radiator inlet hose clamp (3) at the water pump.
15. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
16. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
17. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
18. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
4. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
5. Reposition the radiator inlet hose clamp (3) at the water pump.
6. Remove the radiator inlet hose from the water pump.
7. Reposition the radiator inlet hose and vent inlet hose out of the way.
8. Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .
9. Reposition the radiator outlet hose clamp at the water pump.
10. Remove the radiator outlet hose from the water pump.
11. Reposition the outlet hose out of the way.
12. Reposition the radiator surge tank outlet hose clamp (1) at the water pump.
13. Remove the radiator surge tank outlet hose (2) from the water pump.
14. Reposition the outlet hose out of the way.
15. Reposition the heater inlet hose clamp (1) at the water pump.
16. Remove the heater inlet hose (2) from the water pump.
17. Reposition the inlet hose out of the way.
18. Remove the water pump bolts (1).
19. Remove the water pump (3) and gaskets (2). Discard the gaskets.

Note. All gaskets surfaces are to be free of oil or other foreign material during assembly.

1. Position the water pump (3) and NEW gaskets (2) to the engine block.
2. Install the water pump bolts (1). Tighten: Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the bolts a final pass to 30 N.m (22 lb ft).
3. Position and install the heater inlet hose (2) to the water pump.
4. Position the heater inlet hose clamp (1) at the water pump.
5. Position and install the radiator surge tank outlet hose (2) to the water pump.
6. Position the radiator surge tank outlet hose clamp (1) at the water pump.
7. Position and install the radiator outlet hose to the water pump.
8. Position the radiator outlet hose clamp at the water pump.
9. Install the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-48l-53l-60l-62l-2-of-5) .
10. Position the radiator inlet hose and vent inlet hose to the correct position.
11. Install the radiator inlet hose to the water pump.
12. Position the radiator inlet hose clamp (3) at the water pump.
13. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
14. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
15. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
16. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/testing-diagnostics/#engine-controls-and-fuel-48l-53l-60l-62l-introduction-1-of-2) .

1. Remove the air cleaner outlet duct.
2. Remove the A/C line retainer from the fan shroud.
3. Remove the transmission control module (TCM) retainer (1).
4. Remove TCM from the fan shroud and reposition.
5. Remove the fan shroud retainers (1).
6. Remove the fan shroud bolts (2).
7. Remove the upper fan shroud.

1. Install the upper fan shroud.
2. Install the fan shroud retainers (1).
3. Install the fan shroud bolts (2). Tighten: Tighten the bolts to 9 N.m (80 lb in).
4. Install the transmission control module (TCM) (2).
5. Install the transmission control module (TCM) retainer (1).
6. Install the A/C line retainer to the fan shroud.
7. Install the air cleaner outlet duct.

1. Loosen the air cleaner outlet duct clamps from the throttle body.
2. Loosen the air cleaner outlet duct clamps from the mass airflow sensor (2).
3. Remove the air cleaner outlet duct.
4. If equipped remove the throttle body heater hose retainer from the fan shroud.
5. If equipped remove the inlet radiator hose retainer from the fan shroud.
6. Remove the fan shroud retainers.
7. Remove the fan shroud bolts
8. Remove the upper fan shroud.

1. Install the upper fan shroud.
2. Install the fan shroud bolts. Tighten: Tighten the bolts to 9 N.m (80 lb in).
3. Install the fan shroud retainers.
4. If equipped install the inlet radiator hose retainer to the fan shroud
5. If equipped install the throttle body heater hose retainer to the fan shroud.
6. Install the air cleaner outlet duct.
7. Tighten the air cleaner outlet duct clamp at the throttle body. Tighten: Tighten the clamp to 4 N.m (35 lb in).
8. Tighten the air cleaner outlet duct clamp at the mass airflow sensor (2). Tighten: Tighten the clamp to 4 N.m (35 lb in).

1. Remove the radiator. Refer to «Radiator Replacement (4.3L, 4.8L, 5.3L, and 6.0L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Disengage the two clips from the radiator.
3. If equipped with engine oil cooler, remove the oil cooler hose clip from the lower fan shroud.
4. Remove the shroud from the vehicle.

1. Install the lower fan shroud and ensure it is centered over lower radiator support.
2. Engage the two clips from the radiator.
3. If equipped with the engine oil cooler, Install the oil cooler hose clip to the lower fan shroud.
4. Install the radiator. Refer to «Radiator Replacement (4.3L, 4.8L, 5.3L, and 6.0L)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Replacement (LMM)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan and Shroud Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the radiator outlet hose for the 4.3L engine, or the 4.8L, 5.3L and 6.0L engines. Refer to «Radiator Outlet Hose Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Outlet Hose Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Outlet Hose Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Disconnect the engine oil cooler lines from the radiator, If Equipped. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Disconnect the transmission oil cooler lines from the radiator, If Equipped. Refer to «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(ref-317208-S25377529932009060900000) .
5. Remove the radiator bolts.
6. Remove the radiator.

1. Install the radiator.
2. Install the radiator bolts. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
3. Connect the transmission oil cooler lines to the radiator, If Equipped. Refer to «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(ref-317208-S25377529932009060900000) .
4. Connect the engine oil cooler lines to the radiator, If Equipped. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting Replacement»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Install the radiator outlet hose for the 4.3L engine, or the 4.8L, 5.3L and 6.0L engines. Refer to «Radiator Outlet Hose Replacement (Diesel)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Outlet Hose Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Outlet Hose Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Install the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (Non-HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan and Shroud Replacement (HP2)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 22

Scheme 23

1. Remove the radiator air upper baffle retainers (Qty 8).
2. Remove the radiator air upper baffle.

1. Install the radiator air upper baffle.
2. Install the radiator air upper baffle retainers (Qty 8).

1. Drain the cooling system/engine block. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
3. For 1500 series vehicles, remove the oil pan skid plate bolts and plate, if equipped.
4. For 2500 series vehicle, remove the front 2 oil pan skid plate bolts, loosen the 2 rear bolts and remove the skid plate, if equipped.
5. For vehicles with regular production option (RPO) LY6 (6.0L) perform the following steps otherwise proceed to step 10.
6. Remove the oil cooler hose bracket bolt (1).
7. Remove the oil cooler hose adapter bolts (2).
8. Remove and discard the oil cooler hose adapter gasket.
9. Reposition the oil cooler hose adapter end out of the way.
10. Disconnect the coolant heater cord electrical connector.
11. Remove the coolant heater from the engine block.
12. Remove any burrs, sealer, or other rough spots.

1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
2. Install the coolant heater to the engine block and tighten to 50 N.m (37 lb ft).
3. Connect the coolant heater cord electrical connector.
4. For vehicles with RPO LY6 (6.0L) perform the following steps otherwise proceed to step 9.
5. Position the oil cooler hose adapter end.
6. Install a NEW oil cooler hose adapter gasket.
7. Install the oil cooler hose adapter bolts (2) and tighten to 12 N.m (106 lb in).
8. Install the oil cooler hose bracket bolt (1) and tighten to 25 N.m (18 lb ft).
9. If applicable, for 2500 series vehicles, position the oil pan skid plate and install the 2 front bolts and tighten the 2 rear bolts and tighten to 20 N.m (15 lb ft).
10. If applicable, for 1500 series vehicles position and install the oil pan skid plate and bolts and tighten to 20 N.m (15 lb ft).
11. Lower the vehicle.
12. Fill the cooling system/engine block. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Drain the cooling system/engine block. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
3. Remove the oil pan skid plate bolts and plate, if equipped.
4. For vehicles with regular production option (RPO) L76 (6.0L), perform the following steps. Otherwise, proceed to step 9.
5. Remove the oil cooler hose bracket bolt (1), if equipped.
6. Remove the oil cooler hose adapter bolts (2), if equipped.
7. Remove and discard the oil cooler hose adapter gasket, if equipped.
8. Position the oil cooler hose adapter end out of the way, if equipped.
9. Disconnect the coolant heater cord electrical connector.
10. Remove the coolant heater from the engine block.
11. Remove any burrs, sealer, or other rough spots.

1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
2. Install the coolant heater to the engine block and tighten to 50 N.m (37 lb ft).
3. Connect the coolant heater cord electrical connector.
4. For vehicles with RPO L76 (6.0L) perform the following steps otherwise proceed to step 9.
5. Position the oil cooler hose adapter end, if equipped.
6. Install a NEW oil cooler hose adapter gasket, if equipped.
7. If applicable, install the oil cooler hose adapter bolts (2) and tighten to 12 N.m (106 lb in).
8. If applicable, install the oil cooler hose bracket bolt (1) and tighten to 25 N.m (18 lb ft).
9. If applicable, position and install the oil pan skid plate and bolts and tighten to 20 N.m (15 lb ft).
10. Lower the vehicle.
11. Fill the cooling system/engine block. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Disconnect the heater cord from the coolant heater (4).
3. Loosen the coolant heater bolt.
4. Remove the coolant heater from the engine block.
5. Do not score the machined surface of the hole.
6. Grasp the plug with pliers.
7. Pull the plug from the engine block.
8. Clean the core plug hole in order to remove the following substances: Burrs Compound Paint Rough spots

1. Coat the O-ring seal and the cleaned surface of the plug opening with water resistant high-temperature grease lubricant GM P/N 9985164 (Canadian P/N 10953480), or the equivalent.
2. Tightly push the coolant heater (1) into the engine block.
3. Tighten the coolant heater bolt until both of the locking wings draw tightly against the inner wall of the engine block. Tighten the bolt to 2 N.m (18 lb in).
4. Connect the heater cord to the coolant heater (4).
5. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Inspect the cooling system for leaks.

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the right front tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/wheel-tire-system/#tires-and-wheels) .
3. Remove the right engine mount. Refer to «Engine Mount Replacement - Right Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
4. Disconnect the engine coolant heater cord.
5. Loosen the coolant heater bolt.
6. Remove the engine coolant heater from the engine block.
7. Do not score the machined surface of the hole.
8. Grasp the plug with pliers.
9. Pull the plug from the engine block.
10. Clean the core plug hole in order to remove the following substances: Burrs Compound Paint Rough spots

1. Coat the O-ring seal and the cleaned surface of the plug opening with water resistant high-temperature grease lubricant GM P/N 1052196 (Canadian P/N 5264008), or the equivalent.
2. Align the coolant heater element to point towards the top of the engine.
3. Tightly push the coolant heater into the engine block.
4. Tighten the bolt on the engine coolant heater until both of the locking wings draw tightly against the inner wall of the engine block. Tighten the bolt to 2 N.m (18 lb in).
5. Connect the heater cord to the coolant heater.
6. Remove the right engine mount. Refer to «Engine Mount Replacement - Right Side»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/mechanical/#engine-mechanical-66l-2-of-5) .
7. Install the right front tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/wheel-tire-system/#tires-and-wheels) .
8. Fill the cooling system. Refer to «Cooling System Draining and Filling (Vac-N-Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling System Draining and Filling (Static Fill)»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Inspect for coolant leaks.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
2. Remove the oil pan skid plate bolts and plate, if equipped.
3. Disconnect the coolant heater cord electrical connector.
4. Remove the coolant heater cord retainer (5) from the frame.
5. Remove the coolant heater cord clip (6) from the front brake front pipe.
6. Lower the vehicle.
7. Remove the coolant heater cord bolt (4) from the frame.
8. Remove the coolant heater cord clip (2) from the chassis harness.
9. Remove the coolant heater cord clip (1) from the front spring stud.
10. Remove the coolant heater cord from the vehicle.

1. Install the coolant heater cord to the vehicle.
2. Install the coolant heater cord clip (1) to the front spring stud.
3. Install the coolant heater cord clip (2) to the chassis harness.
4. Position the coolant heater cord clip to the frame and install the coolant heater cord bolt (4). Tighten: Tighten the bolt to 8 N.m (71 lb in).
5. Raise the vehicle.
6. Install the coolant heater cord clip (6) to the front brake front pipe.
7. Position the coolant heater cord clip to the frame and install the coolant heater cord retainer (5).
8. Connect the coolant heater cord electrical connector.
9. Position and install the oil pan skid plate and bolts, if equipped. Tighten: Tighten the bolts to 20 N.m (15 lb ft).
10. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
2. Remove the front 2 oil pan skid plate bolts, loosen the 2 rear bolts and remove the skid plate, if equipped.
3. Disconnect the coolant heater cord electrical connector.
4. Remove the coolant heater cord clip (1) from the front brake front pipes.
5. Remove the coolant heater cord clip retainer (2) from the frame.
6. Lower the vehicle.
7. Remove the coolant heater cord bolt (3) from the frame.
8. Remove the coolant heater cord from the vehicle.

1. Install the coolant heater cord to the vehicle.
2. Position the coolant heater cord clip to the frame and install the coolant heater cord bolt (3). Tighten: Tighten the bolt to 8 N.m (71 lb in).
3. Raise the vehicle.
4. Install the coolant heater cord clip retainer (2) to the frame.
5. Install the coolant heater cord clip (1) to the front brake front pipes.
6. Connect the coolant heater cord electrical connector.
7. Position the oil pan skid plate and install the 2 front bolts and tighten the 2 rear bolts, if equipped. Tighten: Tighten the bolts to 20 N.m (15 lb ft).
8. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cab-chassis-silverado-3500-hd/2008-2011/remont/hoistjack/#general-information) .
2. Remove the oil pan skid plate bolts and plate, if equipped.
3. Disconnect the coolant heater cord electrical connector.
4. Remove the coolant heater cord clip (3) from the engine harness channel.
5. Remove the coolant heater cord clip (1) from the power steering gear outlet hose.
6. Lower the vehicle.
7. Remove the coolant heater cord bolt (2) from the frame.
8. Remove the coolant heater cord from the vehicle.

1. Install the coolant heater cord to the vehicle.
2. Position the coolant heater cord clip to the frame and install the coolant heater cord bolt (2). Tighten: Tighten the bolt to 8 N.m (71 lb in).
3. Raise the vehicle.
4. Install the coolant heater cord clip (1) to the power steering gear outlet hose.
5. Install the coolant heater cord clip (3) to the engine harness channel.
6. Connect the coolant heater cord electrical connector.
7. Position and install the oil pan skid plate and bolts, if equipped. Tighten: Tighten the bolts to 20 N.m (15 lb ft).
8. Lower the vehicle.

Scheme 24

ENGINE COOLANT HOT

The instrument panel cluster (IPC) displays ENGINE COOLANT HOT message when the IPC receives a class 2 message from the engine control module (ECM) requesting illumination of this driver warning.

ENGINE OVERHEATED

The IPC displays ENGINE OVERHEATED message when the IPC receives a class 2 message from the ECM requesting illumination of this driver warning.

LOW COOLANT LEVEL B

The IPC displays LOW COOLANT LEVEL message when the IPC receives a class 2 message from the ECM requesting illumination of this driver warning.

REDUCED ENGINE POWER

The IPC displays REDUCED ENGINE POWER message when the IPC detects a reduced engine power condition from the ECM. The IPC receives a class 2 message from the ECM requesting illumination when the engine temperature exceeds a calibrated value.

Coolant Level Control (If Equipped)

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The engine control module (ECM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The message center receives its power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The cluster receives the class 2 message from the ECM indicating Low Coolant and displays the LOW COOLANT LEVEL message on the driver information center (DIC).

Coolant Heater

The optional engine coolant heater (RPO K05) operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather -18°C (0°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

Auxiliary Coolant Pump (w/HP2)

The auxiliary coolant pump circulates coolant through the engine and heater core when HVAC requires heating and the engine is HOT and OFF. The hybrid control module (HCM) will turn on the auxiliary coolant pump when the HVAC control module commands it to do so by sending a class 2 signal to the HCM.

The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the coolant does not flow to the radiator until the thermostat opens. This allows the engine to warm quickly.

Cooling Cycle

Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Coolant will then be pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders, where it absorbs heat.

Some coolant is also pumped from the water pump to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in regulating the throttle body temperature.

Cooling Cycle (6.6L Diesel Engine)

Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. The coolant flows to the heater core while the engine is running. This provides the passenger compartment with heat and defrost.

Coolant is then pumped through the water pump outlet and through the coolant pipe to the engine oil cooler. The coolant flows around the oil cooler element and to the rear engine cover. The rear engine cover distributes the coolant flow to both banks of the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the turbocharger. There it circulates through passages in the center housing. During engine warm-up cycle the bypass valve located in the turbocharger inlet hose at the outlet pipe prevents coolant flow. During normal operating temperatures, the coolant assists in keeping the turbocharger cool.

From the cylinder heads, the coolant flows to the thermostats. The coolant flows from the thermostat housing to the water pump through the bypass pipe until the enginereaches 85°C (185°F).

Operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components

Coolant

The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and suitable drinking water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.

Radiator

The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a tube and fin crossflow design that extends from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer to the atmosphere.

The inlet and outlet tanks are a molded, high temperature, nylon reinforced plastic material. A high temperature rubber gasket seals the tank flange edge to the aluminum core. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core.

The radiator also has a drain cock located in the bottom of the left hand tank. The drain cock unit includes the drain cock and drain cock seal.

The radiator removes heat from the coolant passing through it. The fins on the core transfer heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.

Surge Tank

The surge tank is a plastic tank with a threaded pressure cap. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system that allows the coolant to expand and contract. The surge tank provides a coolant fill point and a central air bleed location.

During vehicle use, the coolant heats and expands. The increased coolant volume flows into the surge tank. As the coolant circulates, any air is allowed to bubble out. Coolant without air bubbles absorbs heat much better than coolant with bubbles.

Pressure Cap

The pressure cap seals the cooling system. It contains a blow off or pressure relief valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring, which protects the radiator from excessive cooling system pressure. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator and/or coolant hoses to collapse.

The pressure cap allows cooling system pressure to build up as the temperature increases. As the pressure builds, the boiling point of the coolant increases. Engine coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat transfers from the radiator to the cooler, passing air.

The pressure in the cooling system can get too high. When the cooling system pressure exceeds the rating of the pressure cap, it raises the pressure valve, venting the excess pressure.

As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the surge tank. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator and coolant hoses from collapsing.

Cooling Fan and Clutch

The engine cooling fan and clutch are driven by the crankshaft via the drive belt. The cooling fan draws air through the radiator to improve the transfer of heat from the coolant to the atmosphere. As the fan blades spin, they pull cool, outside air past the radiator core. The fan clutch drives the cooling fan. The fan clutch controls the amount of torque that is transmitted from the crankshaft to the fan blades. The clutch allows more torque to engage on the fan when the engine operating temperature increases and/or the vehicle speed is low. As the torque increases, the fan turns more quickly. The fan clutch decreases the torque applied to the cooling fan when the engine temperature decreases and/or the vehicle speed is high. As the torque decreases, the fan speed decreases.

Air Baffles and Seals

The cooling system uses deflectors, air baffles and air seals to increase cooling system capability. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle and through the radiator to increase engine cooling. Air baffles are also used to direct airflow through the radiator and increase cooling capability. Air seals prevent air from bypassing the radiator and A/C condenser, and prevent recirculation of hot air for better hot weather cooling and A/C condenser performance.

Water Pump

The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is mounted on the pump shaft and consists of a series of flat or curved blades or vanes on a flat plate. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force.

The impeller shaft is supported by one or more sealed bearings. The sealed bearings never need to be lubricated. Grease cannot leak out, dirt and water cannot get in as long as the seal is not damaged or worn.

The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.

Water Pump (6.6L Diesel Engine)

The water pump is a centrifugal vane impeller type pump. The water pump is gear driven by the crankshaft gear. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by bearings. Splash of the engine oil lubricates the bearings. The bearings and shaft are sealed to prevent engine oil to mix with the coolant. If the seal fails, coolant will leak out the vent hole in the water pump housing.

The purpose of the water pump is to circulate coolant throughout the cooling system.

Thermostat

The thermostat is a coolant flow control component. It's purpose is to help regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a small piston. When the element is heated, it expands and exerts pressure against the small piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

When the coolant temperature is below the rated thermostat opening temperature, the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up. After the coolant temperature reaches the rated thermostat opening temperature, the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

Thermostats (6.6L Diesel Engine)

The thermostats are coolant flow control components. The purpose of the thermostats are to regulate the correct operating temperature of the engine. The thermostats utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

The 6.6L diesel engine requires two thermostats for correct coolant flow. The front thermostat is a dual purpose thermostat. The front thermostat controls the coolant flow to the bypass port and to the water outlet. The rear thermostat only controls the coolant flow to the water outlet.

When the coolant temperature is below the rated thermostat opening temperature, the front thermostat valve remains closed to the water outlet and is opened to the bypass port. The bottom portion of the thermostat is raised off of the bypass port while at the same time the top portion closes the coolant flow to the water outlet. The rear thermostat also is closed to the water outlet during engine warm-up. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 82°C (180°F) the front thermostat primary valve opening temperature, the front thermostat primary valve will start to open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. As the engine coolant reaches 85°C (185°F) and more coolant demand is required the front thermostat secondary valve begins to close the bypass port and the rear thermostat begins to open coolant flow to the water outlet. The thermostats will continue to control the coolant flow by opening and closing. The thermostat also provides a restriction in the cooling system, even after the it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

Engine Oil Cooler

The engine oil cooler is a heat exchanger. It is located inside the left side end tank of the radiator. The engine oil temperature is controlled by the temperature of the engine coolant that surrounds the oil cooler in the radiator.

The engine oil pump, pumps the oil through the engine oil cooler line to the oil cooler. The oil then flows through the cooler where the engine coolant absorbs heat from the oil. The oil is then pumped through the oil cooler return line, to the oil filter, to the engine block oil system.

Engine Oil Cooler (6.6L Diesel Engine)

The engine oil cooler is a heat exchanger. The engine oil cooler is mounted to the left lower corner of the engine. The oil filter is attached to the oil cooler housing. The engine coolant flows around the oil cooler element. The oil cooler element is a series of plates. The engine oil temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the engine oil passes through the cooler.

The engine oil pump, pumps the oil through the engine oil feed line to the oil cooler. The oil then flows down through the cooler while the engine coolant absorbs heat from the oil. The oil is then pumped through the oil return line, to the oil filter, then to the main engine oil passage.

Transmission Oil Cooler

The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant in the radiator.

The transmission oil pump, pumps the fluid through the transmission oil cooler line to the transmission oil cooler. The fluid then flows through the cooler where the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.

Turbocharger Bypass Valve (6.6L Diesel Engine)

The turbocharger bypass valve is a temperature control valve. The valve is located in the turbocharger coolant inlet hose at the water outlet tube.

The purpose of the valve is to close the coolant flow through the turbocharger. Closing off the coolant flow through the turbocharger avoids turbocharger overcooling.

The instrument panel cluster (IPC) displays ENGINE COOLANT HOT message when the IPC receives a class 2 message from the powertrain control module (PCM) requesting illumination of this driver warning.

The IPC displays ENGINE OVERHEATED message when the IPC receives a class 2 message from the PCM requesting illumination of this driver warning.

The IPC displays LOW COOLANT LEVEL message when the IPC receives a class 2 message from the PCM requesting illumination of this driver warning.

The IPC displays REDUCED ENGINE POWER message when the IPC detects a reduced engine power condition from the PCM. The IPC receives a class 2 message from the PCM requesting illumination when the engine temperature exceeds a calibrated value.

Cooling Fan Control - Two Fan System

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The PCM commands the low speed cooling fans ON under the following conditions

1. Engine coolant temperature exceeds a calibrated value.
2. A/C refrigerant pressure exceeds a calibrated value.
3. After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.

The PCM commands the high speed fans ON under the following conditions

1. Engine coolant temperature exceeds a calibrated value.
2. A/C refrigerant pressure exceeds a calibrated value.
3. When certain DTCs set.

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The powertrain control module (PCM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The message center receives its power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The cluster receives the class 2 message from the PCM indicating Low Coolant and displays the LOW COOLANT LEVEL message on the driver information center (DIC).

The optional engine coolant heater (RPO K05) operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather -18°C (0°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

The auxiliary coolant pump circulates coolant through the engine and heater core when HVAC requires heating and the engine is HOT and OFF. The hybrid control module (HCM) will turn on the auxiliary coolant pump when the HVAC control module commands it to do so by sending a class 2 signal to the HCM.

The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the coolant does not flow to the radiator until the thermostat opens. This allows the engine to warm quickly.

Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Coolant will then be pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders, where it absorbs heat.

Some coolant is also pumped from the water pump to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in regulating the throttle body temperature.

Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. The coolant flows to the heater core while the engine is running. This provides the passenger compartment with heat and defrost.

Coolant is then pumped through the water pump outlet and through the coolant pipe to the engine oil cooler. The coolant flows around the oil cooler element and to the rear engine cover. The rear engine cover distributes the coolant flow to both banks of the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the turbocharger. There it circulates through passages in the center housing. During engine warm-up cycle the bypass valve located in the turbocharger inlet hose at the outlet pipe prevents coolant flow. During normal operating temperatures, the coolant assists in keeping the turbocharger cool.

From the cylinder heads, the coolant flows to the thermostats. The coolant flows from the thermostat housing to the water pump through the bypass pipe until the enginereaches 85°C (185°F).

Operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components

The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and suitable drinking water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.

The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a tube and fin crossflow design that extends from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer to the atmosphere.

The inlet and outlet tanks are a molded, high temperature, nylon reinforced plastic material. A high temperature rubber gasket seals the tank flange edge to the aluminum core. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core.

The radiator also has a drain cock located in the bottom of the left hand tank. The drain cock unit includes the drain cock and drain cock seal.

The radiator removes heat from the coolant passing through it. The fins on the core transfer heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.

The surge tank is a plastic tank with a threaded pressure cap. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system that allows the coolant to expand and contract. The surge tank provides a coolant fill point and a central air bleed location.

During vehicle use, the coolant heats and expands. The increased coolant volume flows into the surge tank. As the coolant circulates, any air is allowed to bubble out. Coolant without air bubbles absorbs heat much better than coolant with bubbles.

The pressure cap seals the cooling system. It contains a blow off or pressure relief valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring, which protects the radiator from excessive cooling system pressure. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator and/or coolant hoses to collapse.

The pressure cap allows cooling system pressure to build up as the temperature increases. As the pressure builds, the boiling point of the coolant increases. Engine coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat transfers from the radiator to the cooler, passing air.

The pressure in the cooling system can get too high. When the cooling system pressure exceeds the rating of the pressure cap, it raises the pressure valve, venting the excess pressure.

As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the surge tank. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator and coolant hoses from collapsing.

The engine cooling fan and clutch are driven by the crankshaft via the drive belt. The cooling fan draws air through the radiator to improve the transfer of heat from the coolant to the atmosphere. As the fan blades spin, they pull cool, outside air past the radiator core. The fan clutch drives the cooling fan. The fan clutch controls the amount of torque that is transmitted from the crankshaft to the fan blades. The clutch allows more torque to engage on the fan when the engine operating temperature increases and/or the vehicle speed is low. As the torque increases, the fan turns more quickly. The fan clutch decreases the torque applied to the cooling fan when the engine temperature decreases and/or the vehicle speed is high. As the torque decreases, the fan speed decreases.

The cooling system uses deflectors, air baffles and air seals to increase cooling system capability. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle and through the radiator to increase engine cooling. Air baffles are also used to direct airflow through the radiator and increase cooling capability. Air seals prevent air from bypassing the radiator and A/C condenser, and prevent recirculation of hot air for better hot weather cooling and A/C condenser performance.

The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is mounted on the pump shaft and consists of a series of flat or curved blades or vanes on a flat plate. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force.

The impeller shaft is supported by one or more sealed bearings. The sealed bearings never need to be lubricated. Grease cannot leak out, dirt and water cannot get in as long as the seal is not damaged or worn.

The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.

The water pump is a centrifugal vane impeller type pump. The water pump is gear driven by the crankshaft gear. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by bearings. Splash of the engine oil lubricates the bearings. The bearings and shaft are sealed to prevent engine oil to mix with the coolant. If the seal fails, coolant will leak out the vent hole in the water pump housing.

The purpose of the water pump is to circulate coolant throughout the cooling system.

The thermostat is a coolant flow control component. It's purpose is to help regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a small piston. When the element is heated, it expands and exerts pressure against the small piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

When the coolant temperature is below the rated thermostat opening temperature, the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up. After the coolant temperature reaches the rated thermostat opening temperature, the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

The thermostats are coolant flow control components. The purpose of the thermostats are to regulate the correct operating temperature of the engine. The thermostats utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

The 6.6L diesel engine requires two thermostats for correct coolant flow. The front thermostat is a dual purpose thermostat. The front thermostat controls the coolant flow to the bypass port and to the water outlet. The rear thermostat only controls the coolant flow to the water outlet.

When the coolant temperature is below the rated thermostat opening temperature, the front thermostat valve remains closed to the water outlet and is opened to the bypass port. The bottom portion of the thermostat is raised off of the bypass port while at the same time the top portion closes the coolant flow to the water outlet. The rear thermostat also is closed to the water outlet during engine warm-up. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 82°C (180°F) the front thermostat primary valve opening temperature, the front thermostat primary valve will start to open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. As the engine coolant reaches 85°C (185°F) and more coolant demand is required the front thermostat secondary valve begins to close the bypass port and the rear thermostat begins to open coolant flow to the water outlet. The thermostats will continue to control the coolant flow by opening and closing. The front thermostat will be fully open when the coolant temperature reaches 95°C (203°F) the rear thermostat will be fully open when the coolant temperature reaches 100°C (212°F). The thermostat also provides a restriction in the cooling system, even after the it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

The engine oil cooler is a heat exchanger. It is located inside the left side end tank of the radiator. The engine oil temperature is controlled by the temperature of the engine coolant that surrounds the oil cooler in the radiator.

The engine oil pump, pumps the oil through the engine oil cooler line to the oil cooler. The oil then flows through the cooler where the engine coolant absorbs heat from the oil. The oil is then pumped through the oil cooler return line, to the oil filter, to the engine block oil system.

The engine oil cooler is a heat exchanger. The engine oil cooler is mounted to the left lower corner of the engine. The oil filter is attached to the oil cooler housing. The engine coolant flows around the oil cooler element. The oil cooler element is a series of plates. The engine oil temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the engine oil passes through the cooler.

The engine oil pump, pumps the oil through the engine oil feed line to the oil cooler. The oil then flows down through the cooler while the engine coolant absorbs heat from the oil. The oil is then pumped through the oil return line, to the oil filter, then to the main engine oil passage.

The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant in the radiator.

The transmission oil pump, pumps the fluid through the transmission oil cooler line to the transmission oil cooler. The fluid then flows through the cooler where the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.

The turbocharger bypass valve is a temperature control valve. The valve is located in the turbocharger coolant inlet hose at the water outlet tube.

The purpose of the valve is to close the coolant flow through the turbocharger. Closing off the coolant flow through the turbocharger avoids turbocharger overcooling.

Illustration Tool Number/Description GE 47716 Vac-N-Fill Coolant Refill Tool J 24460-1 Cooling System Pressure Tester J 24731 Tempil Stick J 26568 Coolant and Battery Fluid Tester J 38185 Hose Clamp Pliers J 41240 or J 46406-A Fan Clutch Remover and Installer Kit includes (36mm) Wrench J 41240-2 Fan Clutch Wrench (36mm) J 41240-5A Fan Clutch Wrench (47mm) J 42401 Radiator Cap/Surge Tank Test Adapter J 43244 Relay Puller Pliers J 46406-1 Fan Clutch Remover and Installer

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See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Component Connector End Views
• Powertrain Component Views
• Electrical Center Identification Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Powertrain Diagnostic Trouble Code (DTC) Type Definitions
• Control Module References
• Diagnostic Repair Verification
• Relay Replacement (Attached to Wire Harness)
• Instrument Cluster Description and Operation
• Audible Warnings Description and Operation
• Coolant in Combustion Chamber
• Coolant in Engine Oil
• Checking Aftermarket Accessories
• Diagnostic Trouble Code (DTC) List - Vehicle
• DTC P0117 or P0118
• Engine Oil and Oil Filter Replacement
• Lifting and Jacking the Vehicle
• Fastener Caution
• Approximate Fluid Capacities
• Air Cleaner Resonator Outlet Duct Replacement
• Engine Shield Replacement
• Drive Belt Replacement
• Generator Bracket Replacement (6.6L)
• Exhaust Gas Recirculation Valve Cooler Replacement
• Power Steering Pump Replacement (6.6L)
• Engine Coolant Thermostat Housing Cleaning and Inspection
• Intake Manifold Replacement (LY2 and LY6)
• Tire and Wheel Removal and Installation
• DTC P0480 or P0481
• Symptoms - Engine Cooling
• Engine Overheating
• Loss of Coolant
• Engine Fails To Reach Normal Operating Temperature
• Pressure Cap Testing
• Fastener Tightening Specifications
• Flushing