Engine Cooling System Chevrolet Chevy Express H1500

Fastener Tightening Specifications

Fastener Tightening Specifications

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Coolant Level Switch (6.6L) Connector & Terminal Parts Information

Coolant Level Switch (6.6L) Terminal Identification

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.

Scan Tool Output Controls

PCM - 4.2L, 5.3L

Scan Tool Data List

Powertrain Control Module 2.4L

Circuit Description

The powertrain control module (PCM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an over temperature condition. This condition occurs when the coolant temperature is above 131°C (268°F). When an over temperature condition is present, DTC P1258 will set. The PCM will disable 2 groups of 4 cylinders by turning OFF the fuel injectors. By switching between the 2 groups of cylinders, the PCM is able to reduce the temperature of the coolant.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P1258 Engine Coolant Overtemperature - Protection Mode Active

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The PCM detects an engine over temperature condition.

Action Taken When the DTC Sets

1. The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed.
2. The PCM will turn ON the Service Engine Soon indicator.
3. The PCM will alternately disable 2 groups of 4 cylinders by turning OFF the fuel injectors.
4. The PCM will store conditions which were present when the DTC set as Freeze Frame and File Records data.

Conditions for Clearing the MIL/DTC

1. The PCM will turn the MIL OFF after 3 consecutive trips that the diagnostic has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P1258

Symptoms - Engine Cooling

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Cooling System. Refer to «Checking Aftermarket Accessories»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Inspect the coolant recovery reservoir for the proper coolant level.

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. «Engine Overheating»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
2. «Loss of Coolant»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
3. «Thermostat Diagnosis»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
4. «Coolant Heater Inoperative (Diesel)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Inoperative (Gasoline)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
5. «Engine Fails To Reach Normal Operating Temperature»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__engine-fails-to-reach-normal-operating)
6. «Fan Clutch Diagnosis»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Low Engine Coolant Indicator Always On

Circuit/System Description

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

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Cooling System Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Scan Tool Output Controls

Circuit/System Verification

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

Circuit/System Testing

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.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Control Module References»(/chevrolet/chevy-express-h1500/2003-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)
3. «Instrument Cluster Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

Repair Verification

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

Engine Overheating

Engine Overheating

Loss of Coolant

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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) . The thermostat should begin to open. J 24731 -206 tempil stick melts at 97°C (206°F). See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) . 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/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/chevy-express-h1500/2003-2012/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/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-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 (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Coolant Heater Cord Replacement (4.3L Engine)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (4.8L, 5.3L And 6.0L Engine)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (6.6L Engine)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/chevy-express-h1500/2003-2012/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/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/chevy-express-h1500/2003-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-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 (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Coolant Heater Cord Replacement (4.3L Engine)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (4.8L, 5.3L And 6.0L Engine)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (6.6L Engine)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)

Engine Fails To Reach Normal Operating Temperature

Engine Fails To Reach Normal Operating Temperature

Pressure Cap Testing

Tools Required

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
2. J 42401 Radiator Cap/Surge Tank Test Adapter. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .

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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) . 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.

Cooling System Leak Testing

Tools Required

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
2. J 42401 Radiator Cap/Surge Tank Test Adapter. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__pressure-cap-testing) .
3. Wash the pressure cap mating surface with water.
4. Install the J 42401 to the surge tank. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
5. Use the J 24460-01 in order to apply pressure to the cooling system. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) . Do not exceed the pressure cap rating.
6. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gage for any pressure loss.
7. Repair any leaks as required.

Noise

Fan noise is sometimes evident when the following normal conditions exist

1. The clutch is engaged for maximum cooling.
2. The engine has been running for 15-60 seconds after start-up. After this time, the clutch can redistribute the silicone fluid back to the normal disengaged operating conditions.

Scheme 5

Fan noise or an excessive roar may occur when the following conditions exist

1. The engine speed is 2,500 RPM or higher.
2. The clutch assembly is locked up due to an internal failure.

Rotate the fan (1).

With the engine off, replace the clutch (2) if the following conditions exist

1. The fan cannot be rotated by hand.
2. The fan produces a rough, grating feel as it turns.

Looseness

If the fan assembly is loose, inspect the fan assembly for wear. Replace the fan assembly as necessary.

Observe the tip of the fan blade for lateral movement. Lateral movement occurs under various temperature conditions. A lateral movement measuring 6.5 mm (1/4 in) is normal. This amount of movement is not cause for replacement of the assembly.

Silicone Fluid Leaks

Small fluid leaks that are present around the bearing assembly do not affect the fan clutch operation. If leakage appears extensive, replace the fan clutch.

Note. Check for adequate clearance between the fan blades and the thermometer sensor before starting the engine, as damage could occur.

Use the following procedure in order to diagnose the causes of engine overheating

1. Ensure that the engine is cool. This will allow complete disengagement of the fan clutch.
2. Spin the fan and clutch assembly by hand. If the fan and clutch assembly easily revolves more than 5 times with no drag, replace the fan clutch.
3. If the fan clutch performs correctly but exhibits drag, position a thermometer between the fan blades and the radiator. Use any of the following methods in order to position the thermometer: Insert the thermometer sensor through one of the existing holes in the fan shroud. Place the thermometer between the radiator and the shroud. On models that do not have holes in the fan shroud, drill a 5 mm (3/16 in) hole in the fan shroud. Insert the thermometer in the hole.
4. Cover the radiator in order to induce a high engine temperature.
5. Start the engine.
6. Turn on the air conditioning.
7. Operate the engine at 2,000 RPM.
8. Wait for 5 to 10 minutes while the temperature increases sufficiently to allow the fan clutch to engage. The following conditions indicate that the fan clutch has engaged: A roaring noise or an increase in fan noise occurs. The thermometer reading drops approximately 3-10°C (5-15°F).
9. Observe the thermometer reading when the fan clutch engages. The following conditions are cause for replacement of the fan clutch: The fan clutch does not engage while the temperature measures 65-90°C (150-195°F). If the fan clutch does not engage while the temperature is within this range, verify that the fan clutch was disengaged at the beginning of the test. Both of the following conditions exist: No temperature drop occurs The fan noise level is constant from the beginning of the test until the time when the engine temperature reaches 88°C (190°F). Do not continue the test past a thermometer reading of 88°C (190°F) in order to prevent overheating.
10. Perform the following steps as soon as the fan clutch engages: Remove the radiator cover. Turn OFF the air conditioning. Operate the engine at approximately 1,500 RPM until the coolant returns to the normal operating temperature.
11. Observe the operation of the fan clutch. The fan clutch should disengage after several minutes. Disengagement of the fan clutch is indicated by a decrease in fan noise or roar. If the fan clutch does not disengage after several minutes, the fan clutch should be replaced.

1. J 26568 Coolant and Battery Tester. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
2. J 38185 Hose Clamp Pliers. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .

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/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
4. Place a drain pan under the lower radiator hose.
5. Using the J 38185 reposition the lower radiator hose clamp at the radiator. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Remove the lower radiator hose from the radiator.
7. Drain the cooling system.
8. If a complete engine block drain is required, remove the engine block drain plug.
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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Filling Procedure

1. Connect the lower radiator hose.
2. Using the J 38185 position the clamp into the original position on the hose. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. If the engine block drain plug was removed, perform the following: Apply pipe sealer to the drain plug. Install the drain plug. Tighten: Tighten the drain plug to 22 N.m (16 lb ft).
4. Lower the vehicle.
5. Using the J 38185 , position the upper radiator hose clamp at the radiator. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Remove the upper radiator hose from the radiator.
7. Remove the coolant air bleed hose from the radiator.
8. Place a funnel into the upper radiator hose.
9. Slowly fill the cooling system through the upper radiator hose with a 50/50 coolant mixture until the coolant comes out the coolant air bleed hose. Refer to «Approximate Fluid Capacities»(/chevrolet/chevy-express-h1500/2003-2012/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
10. Connect the upper radiator hose to the radiator.
11. Using the J 38185 position the radiator hose clamp into the original position on the hose. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
12. Connect the coolant air bleed hose to the radiator.
13. Fill the radiator with coolant through the filler neck.
14. Install the coolant pressure cap.
15. Fill the coolant overflow bottle to the full line.
16. Start the engine.
17. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
18. Allow the engine to idle for 3 minutes.
19. Shut the engine OFF.
20. Allow the engine to cool.
21. Top off the coolant as necessary.
22. Inspect the concentration of the engine coolant, using the J 26568 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
23. Rinse away any excess coolant from the engine and the engine compartment.
24. Inspect the cooling system for leaks.

Draining and Filling Cooling System (Vac N Fill)

Tools Required

1. J 26568 Coolant and Battery Tester. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
2. GE-47716 Vac-N-Fill Coolant Refill Tool. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. J 42401 Radiator Cap and Surge Tank Test Adapter. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .

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/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
4. Place a drain pan under the drain cock.
5. Open the radiator drain cock.
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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Vac-N-Fill Procedure

1. Install the J 42401 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
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/chevy-express-h1500/2003-2012/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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
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/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
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.

Flushing

Radiator Cleaning

An engine will overheat if the radiator has any of the following conditions

1. Leaks
2. Dirt or obstructions in the core

Use a soft bristle brush and clean hot water or a mild detergent solution in order to clean the outside of the radiator core. A car wash or dishwashing liquid is a suitable detergent.

A common city water hose may also be used in order to clean the outside of the radiator. Remove the nozzle from the hose prior to use in order to prevent damage to the fins.

Use one of the following solutions in order to pressure flush and clean the inside of the core tubes

1. Clean hot water
2. Mild car wash
3. Dishwashing liquid

Use the following steps in order to test the radiator for restrictions

1. Warm the engine.
2. Turn off the engine.
3. Feel the radiator. The radiator should be hot along the left side and warm along the right side. There should be an even temperature rise from right to left. Cold spots in the radiator indicate clogged sections.

Cooling Layer Removal

Tools Required

J 38185 Hose Clamp Piers. See Special Tools .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Recover the refrigerant. Refer to «Refrigerant Recovery and Recharging»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__refrigerant-recovery-and-recharging) .
3. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
4. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
5. Remove the surge tank. Refer to «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Remove the front grille. Refer to «Grille Replacement (Base)»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#exterior-trim) or «Grille Replacement (Uplevel)»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#exterior-trim) .
7. Remove the front bumper. Refer to «Front Bumper Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exterior-body-panels/#bumper-system-fascia) .
8. Remove the charge air cooler inlet and outlet ducts. Refer to «Charged Air Cooler Hoses/Pipes Replacement (Inlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Charged Air Cooler Hoses/Pipes Replacement (Outlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
9. Using the J 38185 , reposition the radiator inlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
10. Disconnect the radiator inlet hose from the thermostat housing.
11. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
12. Remove the radiator outlet hose to radiator retaining clip and disconnect the hose.
13. Remove the upper transmission cooler line to radiator retaining clip and disconnect the line.
14. Remove the transmission cooler line to auxiliary transmission cooler retaining clip and disconnect the line.
15. Remove the evaporator to condenser hose retaining nut (1).
16. Disconnect the evaporator to condenser hose from the condenser.
17. Remove the suction hose bolt (1) from the air conditioning (A/C) compressor.
18. Disconnect the suction hose (4) from the A/C compressor.
19. Disconnect the wiring ground located at the RH fender.
20. Remove the RH fender to core support brace bolts and remove the brace.
21. Disconnect the wiring ground located at the LH fender.
22. Remove the LH fender to core support brace bolts and remove the brace.
23. Disconnect the wiring harness electrical connector at the underhood bused electrical center (UBEC).
24. Disconnect the hood release cable at the hood release latch. Position the cable aside.
25. Remove the positive battery cable nut from the junction block and disconnect the cable.
26. Remove the auxiliary positive cable nut from the junction block and disconnect the cable.
27. Remove the positive battery to UBEC cable nut from the junction block and disconnect the cable.
28. Remove the 4 LH and 4 RH core support bolts.
29. Remove the core support and the cooling layer.

Cooling Layer Installation

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Position the core support and the cooling layer to the vehicle.
2. Install the 4 LH and RH core support bolts. Tighten: Tighten the core support bolts to 25 N.m (18 lb ft).
3. Position the positive battery to underhood bused electrical center (UBEC) cable to the junction block and install the nut. Tighten: Tighten the positive battery cable to junction block bolt to 8 N.m (71 lb in).
4. Position the auxiliary positive cable to the junction block and install the nut. Tighten: Tighten the auxiliary positive battery cable to junction block bolt to 8 N.m (71 lb in).
5. Position the positive battery cable to the junction block and install the nut. Tighten: Tighten the positive battery cable to junction block bolt to 8 N.m (71 lb in).
6. Reposition and connect the hood release cable to the hood release latch.
7. Connect the wiring harness electrical connector at the UBEC.
8. Position the LH fender to core support brace and install the bolts.
9. Position the wiring ground to the LH fender and install the bolt. Tighten: Tighten the ground bolt to 9 N.m (80 lb in).
10. Position the RH fender to core support brace and install the bolts.
11. Position the wiring ground to the RH fender and install the bolt. Tighten: Tighten the ground bolt to 9 N.m (80 lb in).
12. Connect the suction hose (4) to the air conditioning (A/C) compressor.
13. Install the suction hose bolt (1) to the A/C compressor. Tighten: Tighten the suction hose bolt to 16 N.m (12 lb ft).
14. Position the evaporator to condenser hose to the condenser.
15. Install the evaporator to condenser hose nut. Tighten: Tighten the evaporator to condenser nut to 16 N.m (12 lb ft).
16. Position the transmission cooler line to the auxiliary transmission cooler and install the retaining clip.
17. Position the upper transmission cooler line to the radiator and install the retaining clip.
18. Lower the vehicle.
19. Position the radiator outlet hose to radiator and install the retaining clip.
20. Connect the radiator inlet hose to the radiator.
21. Using the J 38185 , reposition the radiator inlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
22. Install the charge air cooler inlet and outlet ducts. Refer to «Charged Air Cooler Hoses/Pipes Replacement (Inlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Charged Air Cooler Hoses/Pipes Replacement (Outlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
23. Install the front bumper. Refer to «Front Bumper Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exterior-body-panels/#bumper-system-fascia) .
24. Install the front grille. Refer to «Grille Replacement (Base)»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#exterior-trim) or «Grille Replacement (Uplevel)»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#exterior-trim) .
25. Install the surge tank. Refer to «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
26. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
27. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
28. Recharge the refrigerant. Refer to «Refrigerant Recovery and Recharging»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__refrigerant-recovery-and-recharging) .
29. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

Removal Procedure

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Partially drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the overflow hose from the surge tank.
3. Using J 38185 , reposition the surge tank inlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Remove the surge tank inlet hose from the surge tank.
5. Using J 38185 , reposition the surge tank outlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Disconnect the surge tank outlet hose from the surge tank.
7. Remove the surge tank retaining bolt.
8. Tilt the surge tank assembly and disconnect the surge tank electrical connector.
9. Remove the surge tank from the vehicle.

Installation Procedure

1. Connect the surge tank electrical connector.
2. Install the surge tank to the vehicle.
3. Install the surge tank retaining bolt. Tighten: Tighten the nut to 9 N.m (80 lb in).
4. Install the surge tank outlet hose to the surge tank.
5. Using J 38185 , reposition the surge tank outlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Install the surge tank inlet hose to the surge tank.
7. Using J 38185 , reposition the surge tank inlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
8. Install the overflow hose to the surge tank.
9. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

1. Partially drain the coolant. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Disconnect the hose from the coolant recovery reservoir.
3. Remove the coolant recovery reservoir retaining screws.
4. Remove the coolant recovery reservoir.

1. Install the coolant recovery reservoir.
2. Install the coolant recovery reservoir retaining screws. Tighten: Tighten the screws to 6 N.m (53 lb in).
3. Connect the hose to the coolant recovery reservoir.
4. Add coolant to reservoir. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Partially drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Using J 38185 reposition the surge tank inlet hose clamps. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. Remove the surge tank inlet hose from the surge tank.
4. Remove the surge tank inlet hose from the radiator.

1. Install the surge tank inlet hose to the radiator.
2. Install the surge tank inlet hose to the surge tank.
3. Using J 38185 reposition the surge tank inlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
2. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
3. Using J 38185 , reposition the radiator inlet hose clamps. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Remove the radiator hose from the radiator.
5. Remove the radiator hose from the engine.

1. Install the radiator inlet hose to the engine.
2. Install the radiator inlet hose to the radiator.
3. Using J 38185 , reposition the radiator inlet hose clamps. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
5. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
6. Leak test the cooling system. Refer to «Cooling System Leak Testing»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-leak-testing)

Radiator Inlet Hose Replacement (LU3, LR4, LM7, LQ4)

Tools Required

J 38185 Hose Pliers. See Special Tools .

1. Partially drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Reposition the clamp at the radiator inlet using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. Reposition the clamp at the thermostat housing using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Remove the radiator inlet hose from the radiator.
5. Remove the radiator inlet hose from the thermostat housing.
6. Remove the radiator inlet hose (5).

1. Install the radiator inlet hose (5).
2. Install the radiator inlet hose to the radiator.
3. Install the radiator inlet hose to the thermostat housing.
4. Position the hose clamp at the thermostat housing using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
5. Position the hose clamp at the radiator inlet housing using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Using J 38185 , reposition the radiator outlet hose clamp at the surge tank. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. Remove the radiator outlet hose from the surge tank.
4. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
5. Remove push pin from the small inner wheel panel and position aside.
6. Using J 38185 , reposition the heater hose to radiator outlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
7. Remove the heater hose from the radiator outlet hose.
8. Remove the radiator outlet hose to radiator retaining clip.
9. Remove the radiator outlet hose from the radiator.
10. Loosen the clamp on the radiator outlet hose to engine.
11. Remove the radiator outlet hose from the engine.
12. Remove the radiator outlet hose from the vehicle.

1. Install the radiator outlet hose to the engine.
2. Tighten the clamp on the radiator outlet hose to engine. Tighten: Tighten the clamp to 5 N.m (44 lb in).
3. Install the radiator outlet hose to the radiator.
4. Install the heater hose to the radiator outlet hose.
5. Using J 38185 , reposition the heater hose to radiator outlet hose clamp. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Install wheelhouse panel.
7. Lower the vehicle.
8. Install the radiator outlet hose to the surge tank.
9. Using J 38185 , reposition the radiator outlet hose clamp at the surge tank. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
10. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
11. Leak test the cooling system. Refer to «Cooling System Leak Testing»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-leak-testing)

Radiator Outlet Hose Replacement (LR4, LM7, LQ4)

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the clamp at the radiator outlet using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. Remove the radiator outlet hose clamp at the engine using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Remove the radiator outlet hose clamp at the coolant recovery reservoir using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
5. Remove the radiator outlet hose from the coolant recovery reservoir.
6. Remove the radiator outlet hose from the radiator.
7. Remove the radiator outlet hose from the engine.
8. Remove the radiator outlet hose (4).

1. Install the radiator outlet hose (4).
2. Install the radiator outlet hose to the engine.
3. Install the radiator outlet hose to the radiator.
4. Install the radiator outlet hose to the coolant recovery reservoir.
5. Install the radiator outlet hose clamp to the coolant recovery reservoir using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Install the radiator outlet hose clamp to the engine using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
7. Install the radiator outlet clamp to the radiator outlet using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
8. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

Radiator Outlet Hose Replacement (LU3)

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the clamp at the radiator outlet using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
3. Remove the radiator outlet hose clamp at the engine using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Remove the radiator outlet hose clamp at the coolant recovery reservoir using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
5. Disconnect the radiator outlet hose from the radiator. Refer to «Radiator Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
6. Disconnect the radiator outlet hose from the engine.
7. Remove the radiator outlet hose (4)from the engine compartment.

1. Install the radiator outlet hose (4)into the engine compartment.
2. Connect the radiator outlet hose to the engine.
3. Connect the radiator outlet hose to the radiator. Refer to «Radiator Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
4. Install the radiator outlet hose to the coolant recovery reservoir.
5. Install the radiator outlet hose clamp to the coolant recovery reservoir using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Install the radiator outlet hose clamp to the engine using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
7. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

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.

1. Drain the coolant from the reservoir. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the vent hose from the throttle body.
4. Remove the vent hose from the radiator.
5. Remove the vent hose (1) from the vehicle.

1. Install the vent hose (1) to the vehicle.
2. Connect the vent hose to the radiator.
3. Connect the vent hose to the throttle body.
4. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Fill the reservoir with coolant. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

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. 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.

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 cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Open the oil cooler hose clip located on the lower fan shroud.
3. Remove the oil cooler hoses from the clip.
4. Gently, pull the oil cooler pipe fittings straight out from the radiator quick connect fittings.
5. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
6. Remove the oil cooler hose bracket bolt (1).
7. Remove the oil cooler hose adapter bolts (2).
8. Remove the oil cooler hose assembly and gasket.
9. Discard the gasket.
10. Inspect the fittings, connectors and cooler hoses for damage or distortion.

1. Install the oil cooler hose assembly and a new gasket.
2. Install the oil cooler hose adapter bolts (2). Tighten: Tighten the bolts to 12 N.m (106 lb in).
3. Install the oil cooler hose bracket bolt (1). Tighten: Tighten the bolt to 25 N.m (18 lb ft).
4. Install the oil cooler hoses to the hose clip on the fan shroud.
5. Snap the oil cooler hose clip shut.
6. Connect the oil cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Pull back sharply on the cooler line in order to ensure that the cooler line is installed in the quick connect fitting.

1. Open the hood.
2. Disconnect the oil cooler lines from the auxiliary oil cooler. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system)
3. Remove the auxiliary oil cooler from the vehicle.

1. Install the auxiliary oil cooler.
2. Connect the oil cooler lines to the vehicle. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Lower the vehicle.

1. If a fan assembly fails, inspect the hub and the drive components. A fan assembly may fail due to an imbalance in the hub. This type of failure may not be the fault of the blades.
2. Remove the fan clutch assembly. Refer to «Fan Clutch Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__fan-clutch-replacement) .
3. Remove the fan to fan clutch retaining bolts.
4. Remove the fan from the fan clutch.

1. Install the fan to the fan clutch.
2. Install the fan to fan clutch retaining bolts. Tighten: Tighten the bolts to 23 N.m (17 lb ft).
3. Install the fan clutch assembly. Refer to «Fan Clutch Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__fan-clutch-replacement) .

Fan Clutch Replacement

Tools Required

J 46406 Fan Clutch Remover and Installer

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (4.3L, 4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Install the tool onto the fan clutch nut. Install the J 46406 in order to secure the pulley.
3. Remove the fan clutch assembly.
4. Inspect the following components for cracks, distortion, or other damage: The belt The hub The adapter The pulley
5. Remove the cooling fan from the fan clutch. Refer to «Fan Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Install the cooling fan to the fan clutch. Refer to «Fan Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Install the fan clutch assembly to the pulley.
3. Install the tool onto the fan clutch nut. Install the J 46406 in order to secure the pulley. Tighten: Tighten the nut to 95 N.m (70 lb ft).
4. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (4.3L, 4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 6

Turbocharger Coolant Bypass Valve Replacement

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
2. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
3. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
4. Compress the clamp (1) and disconnect the turbocharger inlet cooling hose/pipe (2) from the thermostat housing.
5. Remove the 3 bolts and the turbocharger heat shield.
6. Remove the left bank fuel return line bracket bolt (1) and the 2 glow plug module bracket bolts (2).
7. Remove the left bank fuel line bracket bolt.
8. Remove the turbocharger inlet cooling hose/pipe bolt and remove the inlet hose/pipe.

1. Position the turbocharger inlet cooling hose/pipe to the vehicle.
2. Using new brass seals, install the turbocharger inlet cooling hose/pipe. Tighten: Tighten the turbocharger inlet cooling hose/pipe bolt to 25 N.m (18 lb ft).
3. Position the left bank fuel line and install the bracket bolt. Tighten: Tighten the fuel line bolt to 25 N.m (18 lb ft).
4. Position the glow module bracket to the valve cover, install the 2 bolts (2) and the remaining left bank fuel line bracket bolt (1). Tighten: Tighten the glow plug module bracket bolts to 10 N.m (89 lb in). Tighten the fuel line bracket bolt to 25 N.m (18 lb ft).
5. Install the turbocharger heat shield and the 3 bolts. Tighten: Tighten the turbocharger heat shield bolts to 10 N.m (89 lb in).
6. Position the turbocharger inlet cooling hose/pipe (2) to the thermostat housing and position the compression clamp (1) to secure.
7. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
8. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
9. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .

1. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
2. Remove the 3 bolts and the turbocharger heat shield.
3. Remove the exhaust gas recirculation (EGR) valve. Refer to «Exhaust Gas Recirculation Valve Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
4. Remove the EGR cooler tube replacement. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
5. Remove the center intake manifold. Refer to «Center Intake Manifold Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Center Intake Manifold Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
6. Remove the thermostat housing crossover. Refer to «Thermostat Housing Crossover Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Thermostat Housing Crossover Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Remove the turbocharger outlet cooling hose/pipe bolt from the valve cover.
8. Remove the turbocharger outlet cooling hose/pipe bolt.
9. Compress the clamp and disconnect the turbocharger cooling hose/pipe from the thermostat bypass pipe.
10. Remove the turbocharger outlet cooler pipe to turbocharger nut.
11. Remove the left bank fuel return line bracket bolt (1) and the two glow plug module bracket bolts (2).
12. Remove the left bank fuel line bracket bolt.
13. Remove the turbocharger outlet cooling hose/pipe to turbocharger bolt and remove the inlet hose/pipe.

1. Position the turbocharger inlet cooling hose/pipe to the vehicle.
2. Using new brass seals, install the turbocharger inlet cooling hose/pipe bolt. Tighten: Tighten the turbocharger inlet cooling hose/pipe bolt to 25 N.m (18 lb ft).
3. Position the left bank fuel line and install the bracket bolt. Tighten: Tighten the fuel line bracket bolt to 25 N.m (18 lb ft).
4. Position the glow module bracket to the valve cover, install the two bolts (2) and the remaining left bank fuel line bracket bolt (1). Tighten: Tighten the glow plug module bracket bolts to 10 N.m (89 lb in). Tighten the fuel line bracket bolt to 25 N.m (18 lb ft).
5. Install the turbocharger heat shield and the 3 bolts. Tighten: Tighten the turbocharger heat shield bolts to 10 N.m (89 lb in).
6. Install the turbocharger outlet cooler pipe to the turbocharger nut. Tighten: Tighten the turbocharger outlet pipe nut to 9 N.m (80 lb in).
7. Compress the clamp and connect the turbocharger cooling hose/pipe to the thermostat bypass pipe.
8. Install the turbocharger outlet cooling hose/pipe to the valve cover. Tighten: Tighten the turbocharger outlet pipe bolt to 9 N.m (80 lb in).
9. Install the turbocharger outlet cooling hose/pipe bolt. Tighten: Tighten the turbocharger outlet cooling hose/pipe bolt to 9 N.m (80 lb in).
10. Install the thermostat housing crossover. Refer to «Thermostat Housing Crossover Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Thermostat Housing Crossover Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
11. Install the center intake manifold. Refer to «Center Intake Manifold Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Center Intake Manifold Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
12. Install the EGR cooler tube replacement. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
13. Install the EGR valve. Refer to «Exhaust Gas Recirculation Valve Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
14. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .

1. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
2. Remove the exhaust gas recirculation (EGR) cooler tube. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
3. Remove the EGR cooler pipe bolt.
4. Reposition the EGR cooler pipe (4) out of the way.
5. Remove the EGR valve adapter pipe bracket bolts (1).
6. Remove the EGR valve adapter pipe bracket (2) and turbocharger heat shield (3).
7. Remove the exhaust gas recirculation (EGR) valve. Refer to «Exhaust Gas Recirculation Valve Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
8. Remove the center intake manifold. Refer to «Center Intake Manifold Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Center Intake Manifold Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
9. Remove the thermostat housing crossover. Refer to «Thermostat Housing Crossover Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Thermostat Housing Crossover Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
10. Remove the turbocharger outlet cooling hose/pipe bolt from the valve cover.
11. Remove the turbocharger outlet cooling hose/pipe bolt.
12. Compress the clamp and disconnect the turbocharger cooling hose/pipe from the thermostat bypass pipe.
13. Remove the turbocharger outlet cooler pipe to turbocharger nut.
14. Remove the left bank fuel return line bracket bolt (1) and the two glow plug module bracket bolts (2).
15. Remove the left bank fuel line bracket bolt.
16. Remove the turbocharger outlet cooling hose/pipe to turbocharger bolt and remove the inlet hose/pipe.

1. Position the turbocharger inlet cooling hose/pipe to the vehicle.
2. Using new brass seals, install the turbocharger inlet cooling hose/pipe bolt. Tighten: Tighten the turbocharger inlet cooling hose/pipe bolt to 25 N.m (18 lb ft).
3. Position the left bank fuel line and install the bracket bolt. Tighten: Tighten the fuel line bracket bolt to 25 N.m (18 lb ft).
4. Position the glow module bracket to the valve cover, install the two bolts (2) and the remaining left bank fuel line bracket bolt (1). Tighten: Tighten the glow plug module bracket bolts to 10 N.m (89 lb in). Tighten the fuel line bracket bolt to 25 N.m (18 lb ft).
5. Install the turbocharger heat shield (3) and EGR valve adapter pipe bracket (2).
6. Install the EGR valve adapter pipe bracket bolts (1). Tighten: Tighten the bolts to 9 N.m (80 lb in).
7. Position the EGR cooler pipe (4).
8. Install the EGR cooler pipe bolt. Tighten: Tighten the bolt to 9 N.m (80 lb in).
9. Install the turbocharger outlet cooler pipe to the turbocharger nut. Tighten: Tighten the turbocharger outlet pipe nut to 9 N.m (80 lb in).
10. Compress the clamp and connect the turbocharger cooling hose/pipe to the thermostat bypass pipe.
11. Install the turbocharger outlet cooling hose/pipe to the valve cover. Tighten: Tighten the turbocharger outlet pipe bolt to 9 N.m (80 lb in).
12. Install the turbocharger outlet cooling hose/pipe bolt. Tighten: Tighten the turbocharger outlet cooling hose/pipe bolt to 9 N.m (80 lb in).
13. Install the thermostat housing crossover. Refer to «Thermostat Housing Crossover Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Thermostat Housing Crossover Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
14. Install the center intake manifold. Refer to «Center Intake Manifold Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Center Intake Manifold Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
15. Install the EGR cooler tube replacement. Refer to «Exhaust Gas Recirculation Valve Cooler Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
16. Install the EGR valve. Refer to «Exhaust Gas Recirculation Valve Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
17. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
18. Perform the turbocharger learn procedure. Refer to «Turbocharger Learn»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2__turbocharger-learn) .

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
2. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
3. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
4. Compress the clamp (1) and disconnect the turbocharger inlet cooling hose/pipe (2) from the thermostat housing.
5. Remove the EGR cooler pipe bolt.
6. Reposition the EGR cooler pipe (4) out of the way.
7. Remove the EGR valve adapter pipe bracket bolts (1).
8. Remove the EGR valve adapter pipe bracket (2) and turbocharger heat shield (3).
9. Remove the left bank fuel return line bracket bolt (1) and the 2 glow plug module bracket bolts (2).
10. Remove the left bank fuel line bracket bolt.
11. Remove the turbocharger inlet cooling hose/pipe bolt and remove the inlet hose/pipe.

1. Position the turbocharger inlet cooling hose/pipe to the vehicle.
2. Using new brass seals, install the turbocharger inlet cooling hose/pipe. Tighten: Tighten the turbocharger inlet cooling hose/pipe bolt to 25 N.m (18 lb ft).
3. Position the left bank fuel line and install the bracket bolt. Tighten: Tighten the fuel line bolt to 25 N.m (18 lb ft).
4. Position the glow module bracket to the valve cover, install the 2 bolts (2) and the remaining left bank fuel line bracket bolt (1). Tighten: Tighten the glow plug module bracket bolts to 10 N.m (89 lb in). Tighten the fuel line bracket bolt to 25 N.m (18 lb ft).
5. Install the turbocharger heat shield (3) and EGR valve adapter pipe bracket (2).
6. Install the EGR valve adapter pipe bracket bolts (1). Tighten: Tighten the bolts to 9 N.m (80 lb in).
7. Position the EGR cooler pipe (4).
8. Install the EGR cooler pipe bolt. Tighten: Tighten the bolt to 9 N.m (80 lb in).
9. Position the turbocharger inlet cooling hose/pipe (2) to the thermostat housing and position the compression clamp (1) to secure.
10. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
11. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
12. Install the air cleaner outlet duct. Refer to «Air Cleaner Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .

Scheme 7

Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (LLY, LBZ)

Scheme 8

Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (LMM)

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
2. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
3. Reposition the EGR cooler pipe clamp (1) and remove the EGR cooler pipe hose from the EGR cooler tube.
4. Remove the upper EGR cooler pipe bolt.
5. Remove the lower EGR cooler pipe bolt (1).
6. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
7. Remove the EGR cooler pipe bolt (1) and bracket (2).
8. 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 bolt. 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 «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
8. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .
2. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
3. Reposition the EGR cooler pipe clamp (1) and remove the EGR cooler pipe hose from the EGR cooler tube.
4. Remove the upper EGR cooler pipe bolt.
5. Remove the lower EGR cooler pipe bolt (1).
6. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
7. Remove the EGR cooler pipe bolt (1) and bracket (2).
8. 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 bolt. 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 «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
8. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/exteriorinterior-trim/#interior-trim-and-paneling) .

1. Remove the bolt from the coolant recovery reservoir and reposition.
2. Remove air cleaner assembly.
3. Remove the radiator outlet hose. Refer to «Radiator Outlet Hose Replacement (LLY)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Outlet Hose Replacement (LR4, LM7, LQ4)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__radiator-outlet-hose-replacement-lr4-lm7) or «Radiator Outlet Hose Replacement (LU3)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__radiator-outlet-hose-replacement-lu3) .
4. Remove the water pump inlet bolts.
5. Remove the water pump inlet and thermostat from the water pump.

1. Install the thermostat and water pump inlet to the water pump.
2. Install the water pump inlet bolts. Tighten: Tighten the water pump inlet bolts to 15 N.m (11 lb ft).
3. Install the radiator outlet hose. Refer to «Radiator Outlet Hose Replacement (LLY)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Outlet Hose Replacement (LR4, LM7, LQ4)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__radiator-outlet-hose-replacement-lr4-lm7) or «Radiator Outlet Hose Replacement (LU3)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__radiator-outlet-hose-replacement-lu3) .
4. Install the air cleaner assembly.
5. Install the coolant recovery reservoir and bolt. Tighten: Tighten the bolt to 11 N.m (97 lb in).

1. Remove the air cleaner and the duct assembly. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) .
2. Partially drain the coolant. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
3. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Disconnect the radiator hose from the thermostat housing.
5. Remove the bolts attaching the thermostat housing to the thermostat.
6. Remove the thermostat housing.
7. Remove the thermostat.
8. Clean the gasket mating surfaces.

Note. Refer to COOLANT ADDITION NOTICE .

1. Install the thermostat.
2. Install the thermostat housing to the intake manifold.
3. Install the bolts to the housing. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
4. Connect the radiator hose to the thermostat housing.
5. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Install the air cleaner and the duct. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) .
7. Refill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
8. Bleed the air from the cooling system.
9. Inspect the thermostat housing and the gasket for coolant leaks.

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (4.3L, 4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the intake manifold. Refer to «Intake Manifold Tube Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Intake Manifold Tube Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
3. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
4. Compress the clamp and disconnect the radiator inlet hose from the thermostat housing.
5. Remove the fuel line bracket bolt and position the fuel line aside.
6. Compress the clamp and disconnect the turbocharger cooling inlet pipe from the thermostat housing.
7. Remove the 4 bolts and the thermostat housing.
8. Remove the thermostat and seals.

Inspection Procedure

1. Inspect the thermostats for sticking, cracks, and/or leakage of wax.
2. Replace the thermostats if damage is found.
3. Clean the thermostat housing and thermostat housing cover sealing surfaces.

1. Install the thermostats and seals to the thermostat housing. The rear thermostat (4) has 2 vent valves. Install the vent valves towards the rear of the engine.
2. Position the thermostat housing and install the 4 bolts. Tighten: Tighten the thermostat housing bolt to 21 N.m (15 lb ft).
3. Compress the clamp and connect the turbocharger cooling inlet pipe to the thermostat housing.
4. Position the fuel line to the thermostat housing and install the fuel line bracket bolt. Tighten: Tighten the fuel line bracket bolt to 21 N.m (15 lb ft).
5. Compress the clamp and connect the radiator inlet hose to the thermostat housing.
6. Install the intake manifold tube. Refer to «Intake Manifold Tube Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Intake Manifold Tube Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
7. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (4.3L, 4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (4.3L, 4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the intake manifold. Refer to «Intake Manifold Tube Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Intake Manifold Tube Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
3. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
4. Compress the clamp and disconnect the radiator inlet hose from the thermostat housing.
5. Disconnect two coolant temperature sensor electrical connectors (1).
6. Remove the fuel pipe bracket bolt (2).
7. Compress the clamp and disconnect the turbocharger cooling inlet pipe from the thermostat housing.
8. Remove the 4 bolts and the thermostat housing.
9. Remove the thermostat and seals.

1. Inspect the thermostats for sticking, cracks, and/or leakage of wax.
2. Replace the thermostats (1, 4) if damage is found.
3. Clean the thermostat housing and thermostat housing cover sealing surfaces.

1. Install the thermostats (1, 4) and seals to the thermostat housing. The rear thermostat (4) has 2 vent valves. Install the vent valves towards the rear of the engine.
2. Position the thermostat housing and install the 4 bolts. Tighten: Tighten the thermostat housing bolt to 21 N.m (15 lb ft).
3. Compress the clamp and connect the turbocharger cooling inlet pipe to the thermostat housing.
4. Install the fuel pipe bracket bolt. Tighten: Tighten the fuel pipe bracket bolt to 25 N.m (18 lb ft).
5. Connect two coolant temperature sensor electrical connectors (1).
6. Compress the clamp and connect the radiator inlet hose to the thermostat housing.
7. Install the intake manifold tube. Refer to «Intake Manifold Tube Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Intake Manifold Tube Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
8. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (4.3L, 4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Upper Shroud Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

1. Remove the radiator fan. Refer to «Fan Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the drive belt tensioner and generator bracket. Refer to «Generator Bracket Replacement (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
3. Remove the air conditioning (A/C) and power steering bracket. Refer to «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
4. Remove the fuel line bolt and position the fuel line aside.
5. Compress the clamp and disconnect the turbocharger inlet cooling hose/pipe.
6. Remove the oil fill tube bolts and the oil fill tube.
7. Disconnect the coolant temperature sensor electrical connector.
8. Remove the exhaust gas recirculation (EGR) coolant pipe. Refer to «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Remove the fuel pipe bracket bolt.
10. Disconnect the hose at the thermostat bypass pipe.
11. Disconnect the radiator inlet hose from the thermostat housing.
12. Remove the thermostat bypass bolts at the water pump.
13. Remove the 8 thermostat housing crossover bolts.
14. Remove the thermostat housing crossover.

1. Position the thermostat housing crossover.
2. Install the 8 thermostat housing crossover bolts. Tighten: Tighten the thermostat housing crossover bolts to 25 N.m (18 lb ft).
3. Install the thermostat bypass bolts to the water pump. Tighten: Tighten to 21 N.m (16 lb ft).
4. Install the radiator inlet hose to the thermostat housing.
5. Connect the hose to the thermostat bypass pipe.
6. Install the fuel pipe bracket bolt. Tighten: Tighten the fuel pipe bracket bolt to 25 N.m (18 lb ft).
7. Install the EGR coolant pipe. Refer to «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Connect the coolant temperature sensor electrical connector.
9. Install the oil fill tube bolts and the oil fill tube. Tighten: Tighten the oil fill tube bolts to 25 N.m (18 lb ft).
10. Compress the clamp and connect the turbocharger inlet cooling hose/pipe.
11. Position the fuel line and install the fuel line bolt.
12. Install the A/C and power steering bracket. Refer to «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
13. Install the drive belt tensioner and generator bracket. Refer to «Generator Bracket Replacement (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
14. Instal the radiator fan. Refer to «Fan Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the cooling layer. Refer to «Cooling Layer Removal»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-layer-removal) .
2. Remove the radiator fan. Refer to «Fan Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the drive belt tensioner and generator bracket. Refer to «Generator Bracket Replacement (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
4. Remove the air conditioning (A/C) and power steering bracket. Refer to «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
5. Remove the fuel line bolt and position the fuel line aside.
6. Compress the clamp and disconnect the turbocharger inlet cooling hose/pipe.
7. Remove the oil fill tube. Refer to «Oil Fill Tube Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
8. Disconnect two coolant temperature sensor electrical connectors (1).
9. Remove the fuel pipe bracket bolt (2).
10. Remove the 8 thermostat housing crossover bolts.
11. Remove the thermostat housing crossover.

1. Position the thermostat housing crossover.
2. Install the 8 thermostat housing crossover bolts. Tighten: Tighten the thermostat housing crossover bolts to 25 N.m (18 lb ft).
3. Install the fuel pipe bracket bolt. Tighten: Tighten the fuel pipe bracket bolt to 25 N.m (18 lb ft).
4. Connect two coolant temperature sensor electrical connectors (1).
5. Install the oil fill tube. Refer to «Oil Fill Tube Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
6. Compress the clamp and connect the turbocharger inlet cooling hose/pipe.
7. Position the fuel line and install the fuel line bolt.
8. Install the A/C and power steering bracket. Refer to «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Air Conditioning (A/C) Compressor and Power Steering Pump Bracket Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
9. Install the drive belt tensioner and generator bracket. Refer to «Generator Bracket Replacement (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Bracket Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
10. Instal the radiator fan. Refer to «Fan Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
11. Install the cooling layer. Refer to «Cooling Layer Removal»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-layer-removal) .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the coolant air bleed pipe bolts (1).
3. Remove the coolant air bleed pipe (2) with gaskets (3).
4. Remove the gaskets from the coolant air bleed pipe and covers.
5. Discard the gaskets.
6. Remove the coolant air bleed hose (1) from the pipe (2).

1. Install the coolant air bleed hose (1) onto the pipe (2).
2. Install the gaskets onto the coolant air bleed pipe and covers.
3. Install the coolant air bleed pipe (2) and gaskets (3) onto the cylinder heads.
4. Install the coolant air bleed pipe bolts (1). Tighten: Tighten the coolant air bleed pipe bolts to 12 N.m (106 lb in).
5. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) .
2. Remove the generator. Refer to «Generator Replacement (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
3. Partially drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
4. Reposition the coolant air bleed hose clamp at the throttle body.
5. Remove the coolant air bleed hose from the throttle body.
6. Position the coolant air bleed hose clamp at the pipe.
7. Remove the coolant air bleed hose (1) from the pipe (2).

1. Install the coolant air bleed hose (1) to the pipe (2).
2. Position the coolant air bleed hose clamp at the pipe.
3. Install the coolant air bleed hose to the throttle body.
4. Position the coolant air bleed hose clamp at the throttle body.
5. Install the generator. Refer to «Generator Replacement (4.3L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
6. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) .
7. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

Scheme 9

Thermostat Bypass Pipes Replacement

Water Pump Replacement (4.3L Engine)

Tools Required

J 41240 Fan Clutch Remover and Installer. See Special Tools .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) .
2. Remove the air cleaner outlet resonator duct. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) .
3. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
4. Remove the cooling fan.
5. Remove the drive belt. Refer to «Drive Belt Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-43l) .
6. Reposition the radiator outlet hose clamps at the surge tank and water pump.
7. Remove the radiator outlet hose from the surge tank.
8. Remove the radiator outlet hose from the water pump.
9. Reposition the water pump inlet hose clamps.
10. Remove the water pump inlet hose.
11. Using J 41240 to hold the water pump pulley, remove the water pump pulley bolts. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
12. Remove the water pump bolts.
13. Remove the water pump.
14. Remove and discard the water pump gaskets.
15. Clean and inspect the water pump, if necessary. Refer to «Water Pump Cleaning and Inspection»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-43l__water-pump-cleaning-and-inspection) .

1. If reusing the 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. NOTE: Refer to «Fastener Notice»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#warnings-and-cautions__fastener-notice) .
3. Install the water pump bolts. Tighten: Tighten the water pump bolts to 45 N.m (33 lb ft).
4. Using J 41240 to hold the water pump pulley, install the water pump pulley bolts. See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) . Tighten: Tighten the water pump pulley 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»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-43l) .
11. Install the cooling fan.
12. Install the air cleaner outlet resonator duct. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) .
13. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) .
14. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
15. Inspect the cooling system for leaks.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) .
3. Remove the fan clutch.
4. Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-48l-53l-and-60l-2-of-4) .
5. Reposition the inlet hose clamp at the water pump.
6. Remove the inlet hose from the water pump.
7. Reposition the outlet hose clamp at the water pump.
8. Remove the outlet hose from the water pump.
9. Reposition the heater inlet hose clamp at the water pump.
10. Remove the heater inlet hose from the water pump.
11. Remove the water pump bolts.
12. Remove the water pump and gaskets.
13. Discard the water pump gaskets.

1. Install the water pump and NEW gaskets.
2. Install the water pump bolts. Tighten: Tighten the water pump bolts a first pass to 15 N.m (11 lb ft). Tighten the water pump bolts a final pass to 30 N.m (22 lb ft).
3. Install the heater inlet hose to the water pump.
4. Position the heater inlet hose clamp at the water pump.
5. Install the outlet hose to the water pump.
6. Position the outlet hose clamp at the water pump.
7. Install the inlet hose to the water pump.
8. Position the inlet hose clamp at the water pump.
9. Install the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-48l-53l-and-60l-2-of-4) .
10. Install the fan blade and clutch assembly.
11. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) .
12. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

1. Remove the thermostat bypass pipes. Refer to «Thermostat Bypass Pipes Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the crankshaft balancer. Refer to «Crankshaft Balancer Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5__crankshaft-balancer-replacement) .
3. Remove the water pump to water pump outlet pipe nuts (2).
4. Remove the engine wiring harness retainer from the water pump bolt.
5. Remove the water pump bolts. Note the location of the bolts. The bolts are three different lengths.
6. Remove the water pump.
7. Remove and discard the water pump O-ring and the water pump outlet pipe gasket.

1. Lubricate the water pump O-ring with engine oil.
2. Install the water pump outlet pipe gasket and water pump O-ring.
3. Install the water pump. NOTE: Refer to «Fastener Notice»(/chevrolet/chevy-express-h1500/2003-2012/remont/oem-general-information/#warnings-and-cautions__fastener-notice) .
4. Install the water pump bolts. Ensure the correct length bolt is used in the proper location. Tighten: Tighten the bolts to 21 N.m (15 lb ft).
5. Install the engine wiring harness retainer onto the water pump bolt.
6. Install the water pump to water pump outlet pipe nuts (2). Tighten: Tighten the nuts to 25 N.m (18 lb ft).
7. Install the crankshaft balancer. Refer to «Crankshaft Balancer Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5__crankshaft-balancer-replacement) .
8. Install the thermostat bypass pipes. Refer to «Thermostat Bypass Pipes Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
2. Remove the water pump to water pump outlet pipe nuts (2).
3. Remove the water pump to water pump outlet pipe studs (1).
4. Remove the water pump outlet pipe.
5. Remove and discard the water pump outlet pipe O-ring and gasket.

1. Install a NEW water pump outlet pipe O-ring onto the pipe.
2. Lubricate the O-ring seal with engine coolant.
3. Position a NEW water pump outlet pipe gasket to the water pump.
4. Install the water pump outlet pipe.
5. Install the water pump to water pump outlet pipe studs (1). Tighten: Tighten the studs to 20 N.m (15 lb ft).
6. Install the water pump to water pump outlet pipe nuts (2). Tighten: Tighten the nuts to 25 N.m (18 lb ft).
7. Lower the vehicle.

1. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, and 6.0L engines.
3. Remove the air cleaner outlet resonator. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine or «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, and 6.0L engines.
4. For the 4.3L engine, remove the air conditioning (A/C) suction hose. Refer to «Suction Hose Replacement (4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) or «Suction Hose Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) for the 4.3L engine.
5. For the 4.8L, 5.3L and 6.0L engine, remove the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (LLY)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Inlet Hose Replacement (LU3, LR4, LM7, LQ4)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__radiator-inlet-hose-replacement-lu3-lr4) .
6. Remove the battery cable from the fan shroud clips and reposition.
7. Remove the mass air flow (MAF) sensor wire from the fan shroud clip and reposition.
8. Remove the transmission oil lever indicator.
9. Remove the fan shroud bolts (1, 3, 4).
10. Remove the fan shroud (2, 5).

1. Install the fan shroud (2, 5).
2. Install the fan shroud bolts (1, 3, 4). Tighten: Tighten the bolts to 6 N.m (53 lb in).
3. Install the transmission oil lever indicator.
4. Install the MAF sensor wire to the fan shroud clip.
5. Install the battery cable to the fan shroud clips.
6. For the 4.3L engine, install the A/C suction hose. Refer to «Suction Hose Replacement (4.8L, 5.3L, 6.0L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) or «Suction Hose Replacement (6.6L)»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) for the 4.3L engine.
7. For the 4.8L, 5.3L and 6.0L engine, install the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (LLY)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Radiator Inlet Hose Replacement (LU3, LR4, LM7, LQ4)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__radiator-inlet-hose-replacement-lu3-lr4) .
8. Install the air cleaner outlet resonator. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine or «Air Cleaner Resonator Outlet Duct Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, and 6.0L engines.
9. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, and 6.0L engines or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine.
10. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the surge tank. Refer to «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the charge air cooler inlet and outlet hoses. Refer to «Charged Air Cooler Hoses/Pipes Replacement (Inlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Charged Air Cooler Hoses/Pipes Replacement (Outlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
3. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
4. Disconnect the fan clutch electrical connector, if equipped.
5. Remove the intake air heater. Refer to «Intake Air Heater Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
6. Disconnect the cross car harness at buss bar on right core support.
7. Position cross car harness out of way.
8. Remove the transmission oil indicator.
9. Remove the engine oil indicator.
10. Remove the engine oil fill cap.
11. Remove the 2 upper fan shroud to core support bolts.
12. Remove the fan clutch electrical wiring harness routing clip, if equipped.
13. Remove the 4 upper fan shroud to lower fan shroud bolts.
14. Remove the upper fan shroud, while positioning the upper radiator hose.

1. Position the upper fan shroud in the vehicle, while positioning the upper radiator hose.
2. Install the 4 upper fan shroud to lower fan shroud bolts. Tighten: Tighten the upper fan shroud to lower fan shroud bolts to 6 N.m (53 lb in).
3. Install the fan clutch electrical wiring harness routing clip, if equipped.
4. Install the 2 upper fan shroud to core support bolts. Tighten: Tighten the upper fan shroud to core support bolts to 6 N.m (53 lb in).
5. Install the engine oil fill cap.
6. Install the engine oil indicator.
7. Install the transmission oil indicator.
8. Position back cross car harness.
9. Connect the cross car harness on buss bar at right core support.
10. Install the intake air heater. Refer to «Intake Air Heater Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
11. Connect the fan clutch electrical connector, if equipped.
12. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
13. Install the charge air cooler inlet and outlet hoses. Refer to «Charged Air Cooler Hoses/Pipes Replacement (Inlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Charged Air Cooler Hoses/Pipes Replacement (Outlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
14. Install the surge tank. Refer to «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, 6.0L engines or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine.
3. Remove the fan shroud bolts (1,3,4).
4. Remove the fan shroud (2,5).

1. Install the fan shroud (2,5).
2. Install the fan shroud bolts (1,3,4). Tighten: Tighten the bolts to 6 N.m (53 lb in).
3. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, 6.0L engines or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine.
4. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
2. Remove the upper fan shroud to lower fan shroud retaining bolts.
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
4. Remove the lower fan shroud retaining bolts.
5. Remove the lower fan shroud from the vehicle.

1. Install the lower fan shroud to the vehicle.
2. Install the lower fan shroud retaining bolts. Tighten: Tighten the bolts to 6 N.m (53 lb in).
3. Lower the vehicle.
4. Install the upper fan shroud to lower fan shroud retaining bolts. Tighten: Tighten the bolts to 6 N.m (53 lb in).
5. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .

Radiator Replacement (Diesel)

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
2. Remove the upper radiator baffle.
3. Remove the surge tank. Refer to «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove battery. Refer to «Battery Replacement (Primary)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Battery Replacement (Secondary)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
5. Remove the charged air cooler inlet hose/pipe. Refer to «Charged Air Cooler Hoses/Pipes Replacement (Inlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Charged Air Cooler Hoses/Pipes Replacement (Outlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
6. Remove the clamp at the radiator inlet using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
7. Remove the radiator inlet hose (5) from the radiator.
8. Remove the outlet heater hose clamp at the radiator using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
9. Remove the outlet heater hose (2) from the radiator.
10. Remove the automatic transmission cooler lines. Refer to «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l60-e4l65-e4l70-e-removal-installation-service-troubleshooting-diagnosis) for the 4L60-E/4L65-E/4L70-E transmissions or «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l80-e4l85-e-removal-installation-service-troubleshooting-diagnosis) for the 4L80-E/4L85-E transmissions.
11. Remove the engine oil cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Remove the engine oil fill tube. Refer to «Oil Fill Tube Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
13. Remove intake manifold tube. Refer to «Intake Manifold Tube Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Intake Manifold Tube Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
14. Remove the upper radiator baffle. Remove the fan shroud bolts (1) from the top of the radiator support.
15. Remove the fan shroud bolts (3) from the sides of the fan shroud.
16. Remove the radiator mounting bolts from the charged air cooler.
17. Remove the charge air cooler bolts to core support.
18. Remove the radiator and charge air cooler as assembly.
19. Remove radiator bolts to charge air cooler.
20. Remove the radiator insulators.
21. Inspect the following components: The radiator The insulators The hoses and clamps The mounting hardware Replace the components as necessary.

1. Install the radiator insulators.
2. Install the radiator to the charge air cooler. Tighten: Tighten the bolts to 6 N.m (53 lb in).
3. Install the radiator and charge air cooler as an assembly.
4. Install the radiator mounting bolts to the charged air cooler. Tighten: Tighten the bolts to 6 N.m (53 lb in).
5. Install the fan shroud bolts (1) to the top of the radiator support. Tighten: Tighten the bolts to 6 N.m (53 lb in).
6. Install the fan shroud bolts (3) to the sides of the fan shroud. Tighten: Tighten the bolts to 6 N.m (53 lb in).
7. Install the engine oil cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Install the automatic transmission oil cooler lines. Refer to «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l60-e4l65-e4l70-e-removal-installation-service-troubleshooting-diagnosis) for the 4L60-E/4L65-E/4L70-E transmissions or «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l80-e4l85-e-removal-installation-service-troubleshooting-diagnosis) for the 4L80-E/4L85-E transmissions.
9. Install the radiator inlet hose (5) to the radiator.
10. Install the hose clamp at the radiator inlet housing using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
11. Install the outlet heater hose (2).
12. Install the outlet heater hose clamp using the J 39529 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
13. Install the intake manifold tube. Refer to «Intake Manifold Tube Replacement (LLY, LBZ)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Intake Manifold Tube Replacement (LMM)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
14. Install oil fill tube. «Oil Fill Tube Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
15. Install the upper radiator baffle.
16. Install the battery. Refer to «Battery Replacement (Primary)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Battery Replacement (Secondary)»(/chevrolet/chevy-express-h1500/2003-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
17. Install the charged air cooler hose/pipe. Refer to «Charged Air Cooler Hoses/Pipes Replacement (Inlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) or «Charged Air Cooler Hoses/Pipes Replacement (Outlet)»(/chevrolet/chevy-express-h1500/2003-2012/remont/mechanical/#engine-mechanical-66l-2-of-5) .
18. Install the surge tank assembly. Refer to «Surge Tank Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
19. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-66l-lbz-and-lly-introduction-2-of-2) .
20. Install the upper radiator baffle.
21. Inspect the automatic transmission fluid level. Refer to «Approximate Fluid Capacities»(/chevrolet/chevy-express-h1500/2003-2012/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
22. Inspect the engine oil level. Refer to «Approximate Fluid Capacities»(/chevrolet/chevy-express-h1500/2003-2012/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .

Radiator Replacement (Gas)

Tools Required

J 38185 Hose Clamp Pliers. See Special Tools .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, 6.0L engines or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine.
2. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the clamp at the radiator inlet using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Remove the radiator inlet hose (5) from the radiator.
5. Remove the outlet heater hose clamp at the radiator using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
6. Remove the outlet heater hose (2) from the radiator.
7. Remove the automatic transmission cooler lines. Refer to «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l60-e4l65-e4l70-e-removal-installation-service-troubleshooting-diagnosis) for the 4L60-E/4L65-E/4L70-E transmission or «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l80-e4l85-e-removal-installation-service-troubleshooting-diagnosis) for the 4L80-E/4L85-E transmission.
8. Remove the engine oil cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Remove the fan shroud bolts (1) from the top of the radiator support.
10. Remove the fan shroud bolts (3) from the sides of the fan shroud.
11. Remove the radiator (2).
12. Remove the radiator insulators (1, 3).
13. Inspect the following components: The radiator The insulators The hoses and clamps The mounting hardware Replace the components as necessary.

1. Install the radiator insulators (1, 3).
2. Install the radiator (2).
3. Install the fan shroud bolts (1) to the top of the radiator support. Tighten: Tighten the bolts to 6 N.m (53 lb in).
4. Install the fan shroud bolts (3) to the sides of the fan shroud. Tighten: Tighten the bolts to 6 N.m (53 lb in).
5. Install the engine oil cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Install the automatic transmission oil cooler lines. Refer to «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l60-e4l65-e4l70-e-removal-installation-service-troubleshooting-diagnosis) for the 4L60-E/4L65-E/4L70-E transmission or «Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/chevrolet/chevy-express-h1500/2003-2012/remont/automatic-trans/#how-to-overhaul-the-automatic-transmission-4l80-e4l85-e-removal-installation-service-troubleshooting-diagnosis) for the 4L80-E/4L85-E transmission.
7. Install the radiator inlet hose (5) to the radiator.
8. Install the hose clamp at the radiator inlet housing using the J 38185 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
9. Install the outlet heater hose (2).
10. Install the outlet heater hose clamp using the J 39529 . See «Special Tools»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
11. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-48l-53l-and-60l-introduction-2-of-2) for the 4.8L, 5.3L, 6.0L engines or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-h1500/2003-2012/remont/testing-diagnostics/#engine-control-system-fuel-system-43l-introduction-2-of-2) for the 4.3L engine.
13. Inspect the automatic transmission fluid level. Refer to «Approximate Fluid Capacities»(/chevrolet/chevy-express-h1500/2003-2012/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
14. Inspect the engine oil level. Refer to «Approximate Fluid Capacities»(/chevrolet/chevy-express-h1500/2003-2012/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
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: 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 «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
6. Inspect the cooling system for leaks.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
3. Disconnect the coolant heater electrical connector (2).
4. Remove the coolant heater from the engine block.
5. Remove any burrs, sealer, paint or other rough spots.

1. If re-using 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. Tighten: Tighten the coolant heater to 50 N.m (37 lb ft).
3. Connect the coolant heater electrical connector (2).
4. Lower the vehicle.
5. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
2. Remove the right front tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/chevy-express-h1500/2003-2012/remont/wheel-tire-system/#tires-and-wheels) .
3. Disconnect the engine coolant heater cord.
4. Loosen the coolant heater bolt.
5. Remove the engine coolant heater from the engine block.
6. Do not score the machined surface of the hole.
7. Grasp the plug with pliers.
8. Pull the plug from the engine block.
9. 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: Tighten the bolt to 2 N.m (18 lb in).
5. Connect the heater cord to the coolant heater.
6. Install the right front tire and wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/chevy-express-h1500/2003-2012/remont/wheel-tire-system/#tires-and-wheels) .
7. Fill the cooling system. Refer to «Draining and Filling Cooling System (Static Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Draining and Filling Cooling System (Vac N Fill)»(/chevrolet/chevy-express-h1500/2003-2012/remont/cooling-system-mechanical/#engine-cooling-system__draining-and-filling-cooling-system-vac) .
8. Inspect for coolant leaks.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
2. Disconnect the coolant heater electrical connector (1).
3. Remove the coolant heater cord retainer (1).
4. Remove the coolant heater cord retainers (1).
5. Remove the coolant heater cord.

Note. The heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Route the cord to the left front of the engine compartment securing with tie straps as necessary to prevent damage.

1. Install the coolant heater cord.
2. Install the coolant heater cord retainer (1).
3. Install the coolant heater cord retainers (1).
4. Connect the coolant heater electrical connector (1).
5. Lower the vehicle.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
2. Disconnect the coolant heater electrical connector (1).
3. Remove the coolant heater cord retainers (1).
4. Remove the coolant heater cord.

Note. The heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Route the cord to the left front of the engine compartment securing with tie straps as necessary to prevent damage.

1. Install the coolant heater cord.
2. Install the coolant heater cord retainers (1).
3. Connect the coolant heater electrical connector (1).
4. Lower the vehicle.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-h1500/2003-2012/remont/hoistjack/#general-information) .
2. Disconnect the coolant heater electrical connector (1).
3. Remove the coolant heater cord retainer (1).
4. Remove the coolant heater cord retainer (1).
5. Remove the coolant heater cord retainer (1).
6. Remove the coolant heater cord.

Note. The heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Route the cord to the left front of the engine compartment securing with tie straps as necessary to prevent damage.

1. Install the coolant heater cord.
2. Install the coolant heater cord retainer (1).
3. Install the coolant heater cord retainer (1).
4. Install the coolant heater cord retainer (1).
5. Connect the coolant heater electrical connector (1).
6. Lower the vehicle.

Coolant Heater

The optional engine coolant heater (RPO KO5) is designed to warm the coolant in the engine block area for improved starting in very cold weather (temperatures below -29°C (-20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The engine coolant heater operates using AC external power and a heating element installed in the water jacket of the engine block. The heating element warms the coolant when the heater cord is plugged into an AC power source.

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 cooling systems 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 Level Control

The engine cooling system contains an engine coolant level switch which alerts the driver in the event of a coolant loss. When the engine coolant level switch reads a low coolant level in the surge tank, the switch opens. This sends a coolant loss signal to the instrument panel cluster (IPC) by the coolant level switch signal circuit. Ground is provided for the coolant level control.

Cooling Cycle

Coolant flows from the radiator outlet and into the water pump inlet. Some coolant flows from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost capability as the coolant warms up.

Coolant also flows from 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.

The coolant then flows 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.

Some engine applications, coolant is also directed to the throttle body. There it circulates through passages in the casting. The coolant assists in regulating the throttle body temperature.

From the cylinder heads, the coolant flows to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine reaches operating temperature or it will flow through the thermostat and into the radiator where it is cooled. At this point, the coolant flow cycle is completed.

Efficient 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 2 tanks. The aluminum core is a tube and fin cross-flow 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.

During vehicle use, the coolant is heated 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.

Coolant Recovery System

The coolant recovery system consists of a plastic coolant recovery reservoir, an overflow tube, and a pressure cap on the radiator. The recovery reservoir is also called a recovery tank or expansion tank. It is partially filled with coolant and is connected to the radiator fill neck with the overflow tube. Coolant can flow back and forth between the radiator and the reservoir.

In effect, a cooling system with a coolant recovery reservoir is a closed system. When the pressure in the cooling system gets too high, it will open the pressure valve in the pressure cap. This allows the coolant, which has expanded due to being heated, to flow through the overflow tube and into the recovery reservoir. As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum opens the vacuum valve in the pressure cap, allowing some of the coolant in the reservoir to be siphoned back into the radiator. Under normal operating conditions, no coolant is lost. Although the coolant level in the recovery reservoir goes up and down, the radiator and cooling system are kept full. An advantage to using a coolant recovery reservoir is that it eliminates almost all air bubbles from the cooling system. 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, a retaining plate, pulley 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.

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 a 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 85°C (185°F) for diesel engines and below 91°C (195°F) for gas engines, the thermostat valve remains closed. This prevents circulation of the coolant from the radiator and allows the engine to warm up. After the coolant temperature reaches 85°C (185°F) or 91°C (195°F), the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the engine and then 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.

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.

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.

Special Tools

Special Tools Illustration Tool Number/ Description J 24460-01 Cooling System Pressure Tester J 24731 Tempil Stick J 26568 Coolant and Battery Fluid Tester J 38185 Hose Clamp Pliers J 39529 Wiper Linkage Installer J 41240 Fan Clutch Remover and Installer J 42401 Radiator Cap and Surge Tank Test Adapter GE 47716 Vac-N-Fill Coolant Refill Tool

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

See also:
• Diagnostic System Check - Vehicle
• Checking Aftermarket Accessories
• Testing for Intermittent Conditions and Poor Connections
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Circuit Testing
• Connector Repairs
• Wiring Repairs
• Diagnostic Repair Verification
• Control Module References
• Instrument Cluster Replacement
• Heater Core Replacement
• Engine Oil and Oil Filter Replacement
• Engine Coolant/Water in Transmission
• Engine Coolant/Water in Transmission
• Engine Will Not Crank - Crankshaft Will Not Rotate
• Coolant in Combustion Chamber
• Coolant in Engine Oil
• Lower Engine Noise, Regardless of Engine Speed
• Cylinder Leakage Test
• Lifting and Jacking the Vehicle
• Approximate Fluid Capacities
• Refrigerant Recovery and Recharging
• Battery Negative Cable Disconnection and Connection
• Air Cleaner Assembly Replacement
• Grille Replacement (Base)
• Front Bumper Replacement
• Charged Air Cooler Hoses/Pipes Replacement (Inlet)
• Fastener Notice
• Component Fastener Tightening Notice
• Engine Cover Replacement
• Turbocharger Learn
• Air Cleaner Outlet Resonator Replacement
• COOLANT ADDITION NOTICE
• Air Cleaner Assembly Replacement
• Drive Belt Replacement
• Water Pump Cleaning and Inspection
• Crankshaft Balancer Replacement
• Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection
• Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection
• Tire and Wheel Removal and Installation
• Engine Overheating
• Symptoms - Engine Cooling
• Cooling System Description and Operation
• Loss of Coolant
• Engine Fails To Reach Normal Operating Temperature
• Scan Tool Output Controls
• Water Pump Replacement (4.3L Engine)
• Radiator Replacement (Diesel)
• Radiator Replacement (Gas)
• Draining and Filling Cooling System (Vac N Fill)
• Cooling System Leak Testing
• Pressure Cap Testing
• Special Tools
• Flushing
• Fan Clutch Replacement
• Fastener Tightening Specifications
• Radiator Outlet Hose Replacement (LR4, LM7, LQ4)
• Radiator Outlet Hose Replacement (LU3)
• Cooling Layer Removal
• Radiator Inlet Hose Replacement (LU3, LR4, LM7, LQ4)