Engine Cooling System Chevrolet Chevy Express G2500

Fastener Tightening Specifications

Fastener Tightening Specifications

Diagnostic Starting Point - Engine Cooling

Begin the system diagnosis by reviewing the system Description and Operation. Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Cooling in order to identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 2: Lack of communication may be due to a partial malfunction of the Class 2 serial data circuit or due to a total malfunction of the Class 2 serial data circuit. The specified procedure will determine the particular condition.
2. 3: Determine if the Powertrain Control Module has set DTCs which may affect Engine Cooling operation are present.
3. 4: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Diagnostic System Check - Engine Cooling

Scan Tool Data List

Powertrain Control Module (PCM) Scan Tool Data List

Diagnostic Trouble Code (DTC) List

Diagnostic Trouble Code (DTC) List

Circuit Description

The PCM uses the 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 two groups of four cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders, the PCM is able to reduce the temperature of the coolant.

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 four 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-g2500/1996-2012/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__checking-aftermarket-accessories) in Wiring Systems.
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 in Wiring Systems.

Symptom List

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

1. «Engine Overheating»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
2. «Loss of Coolant»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
3. «Thermostat Diagnosis»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis)
4. «Coolant Heater Inoperative»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system__coolant-heater-inoperative)
5. «Engine Fails To Reach Normal Operating Temperature»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system__engine-fails-to-reach-normal-operating)
6. «Fan Clutch Diagnosis»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system)

Engine Overheating

Engine Overheating

Loss of Coolant

Loss of Coolant

Thermostat Diagnosis

Tools Required

J 24731 Tempil Stick. See Special Tools and Equipment .

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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) . The thermostat should begin to open. J 24731 - 206 tempil stick melts at 97°C (206°F). See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) . The thermostat should be fully open.
2. Replace the coolant thermostat if it does not operate properly between this temperature range.

Thermostat Test Procedure Using Glycol

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

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

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

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

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

Coolant Heater Inoperative

Coolant Heater Inoperative

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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 42401 Radiator Cap/Surge Tank Test Adapter.

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.
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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) . Maintain the rated pressure for at least 10 seconds. Note the rate of pressure loss.
5. Replace the pressure cap under the following conditions: The pressure cap does not release pressure which exceeds the rated pressure of the cap. The pressure cap does not hold the rated pressure.

Cooling System Leak Testing

Tools Required

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 42401 Radiator Cap/Surge Tank Test Adapter

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(/chevrolet/chevy-express-g2500/1996-2012/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.
5. Use the J 24460-01 in order to apply pressure to the cooling system. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) . 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.

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. Refer to «Fan Clutch Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 1

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. Refer to Fan Clutch Replacement .

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.

Tools Required

J 26568 Coolant and Battery Tester. See Special Tools and Equipment .

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-g2500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Place a drain pan under the lower radiator hose.
5. Remove the clip from the radiator hose quick connect at the radiator.
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-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Filling Procedure

1. Place the clip (1) into the hose and connect the lower radiator hose (2).
2. Apply firm pressure until you hear the clip engage.
3. Gently tug on the hose to ensure the clip is properly seated.
4. 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).
5. Lower the vehicle.
6. Using the J 38185 , position the upper radiator hose clamp at the radiator. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Remove the upper radiator hose from the radiator.
8. Remove the coolant air bleed hose from the radiator.
9. Place a funnel into the upper radiator hose.
10. 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 «Capacities - Approximate Fluid»(/chevrolet/chevy-express-g2500/1996-2012/remont/lubrication-system/#maintenance-and-lubrication__capacities-approximate-fluid) in General Information.
11. Connect the upper radiator hose to the radiator.
12. Using the J 38185 position the radiator hose clamp into the original position on the hose. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
13. Connect the coolant air bleed hose to the radiator.
14. Fill the radiator with coolant through the filler neck.
15. Install the coolant pressure cap.
16. Fill the coolant overflow bottle to the full line.
17. Start the engine.
18. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
19. Allow the engine to idle for 3 minutes.
20. Shut the engine OFF.
21. Allow the engine to cool.
22. Top off the coolant as necessary.
23. Inspect the concentration of the engine coolant, using the J 26568 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
24. Rinse away any excess coolant from the engine and the engine compartment.
25. Inspect the cooling system for leaks.

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. Refer to «Cooling System Description and Operation»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) for a radiator diagram.

Removal Procedure

1. Partially drain the coolant. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Disconnect the hose from the coolant recovery reservoir.
3. Remove the coolant recovery reservoir retaining screws.
4. Remove the coolant recovery reservoir.

Installation Procedure

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»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

J 38185 Hose Pliers. See Special Tools and Equipment .

1. Partially drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the clamp at the radiator inlet using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the clamp at the thermostat housing using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Position the hose clamp at the radiator inlet housing using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Fill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

J 38185 Hose Pliers. See Special Tools and Equipment .

1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the radiator outlet hose clamp at the engine using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the radiator outlet hose clamp at the coolant recovery reservoir using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the radiator outlet hose from the coolant recovery reservoir.
5. Remove the radiator outlet hose from the radiator.
6. Remove the radiator outlet hose from the engine.
7. 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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Install the radiator outlet hose clamp to the engine using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Install the radiator outlet clamp to the radiator outlet using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Fill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Drain the coolant from the reservoir. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/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-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Fill the reservoir with coolant. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

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-g2500/1996-2012/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-g2500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in 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-g2500/1996-2012/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-g2500/1996-2012/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-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Lower the vehicle.

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

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 upper fan shroud. Refer to «Fan Shroud Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Insert the tool around the pulley in order to secure the pulley. Insert the J 41240 onto the fan clutch nut. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the following components: The fan (1) The fan clutch (2)
5. Inspect the following components for cracks, distortion, or other damage: The belts The hub The adapter The pulley
6. Replace the components, as necessary.

1. Install the following components: The fan (1) The fan clutch (2) Tighten: Tighten the fan clutch nut to 145 N.m (107 lb ft).
2. Install the upper fan shroud. Refer to «Fan Shroud Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

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

1. Remove the fan shroud bolts (1) from the top of the radiator support.
2. Remove the fan shroud bolts (3) from the sides of the fan shroud.
3. Remove the upper fan shroud (2).
4. Install the tool onto the fan clutch nut. Install the J 41240 in order to secure the pulley. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Remove the fan clutch assembly.
6. Inspect the following components for cracks, distortion, or other damage: The belt The hub The adapter The pulley
7. Remove the bolts from the fan clutch.
8. Separate the fan clutch from the fan blade.

1. Install the fan clutch (2) to the fan blade (1).
2. Install the bolts to the fan clutch. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
3. Install the fan clutch assembly to the pulley.
4. Install the tool onto the fan clutch nut. Install the J 41240 in order to secure the pulley. See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) . Tighten: Tighten the nut to 95 N.m (70 lb ft).
5. Install the upper fan shroud (2).
6. Install the fan shroud bolts (1) to the top of the radiator support. Tighten: Tighten the bolts to 6 N.m (53 lb in).
7. Install the fan shroud bolts (3) to the sides of the fan shroud. Tighten: Tighten the bolts to 6 N.m (53 lb in).

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 Hose Replacement - Outlet»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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 Hose Replacement - Outlet»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
2. Partially drain the coolant. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/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 in Cautions and Notices.

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-g2500/1996-2012/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-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
7. Refill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Bleed the air from the cooling system.
9. Inspect the thermostat housing and the gasket for coolant leaks.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 5.3L, and 6.0L.
2. Remove the generator. Refer to «Generator Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-g2500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (4.3L)»(/chevrolet/chevy-express-g2500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
3. Partially drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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 (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-g2500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Generator Replacement (4.3L)»(/chevrolet/chevy-express-g2500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
6. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, and 6.0L.
7. Fill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

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

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
2. Remove the air cleaner outlet resonator duct. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
3. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the cooling fan. Refer to «Fan Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Remove the drive belt. Refer to «Drive Belt Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/mechanical/#engine-mechanical-43l) in Engine Mechanical - 4.3L.
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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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-g2500/1996-2012/remont/mechanical/#engine-mechanical-43l) in Engine Mechanical - 4.3L. Unit Repair.

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-g2500/1996-2012/remont/oem-general-information/#cautions-and-notices__fastener-notice) in Cautions and Notices.
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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) . 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-g2500/1996-2012/remont/mechanical/#engine-mechanical-43l) in Engine Mechanical - 4.3L.
11. Install the cooling fan. Refer to «Fan Clutch Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Install the air cleaner outlet resonator duct. Refer to «Air Cleaner Outlet Resonator Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
13. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
14. Fill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
15. Inspect the cooling system for leaks.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 5.3L and 6.0L.
3. Remove the fan clutch. Refer to «Fan Clutch Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/chevrolet/chevy-express-g2500/1996-2012/remont/mechanical/#engine-mechanical-removal-installation-1-of-3-48l-53l-60l) .
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-g2500/1996-2012/remont/mechanical/#engine-mechanical-removal-installation-1-of-3-48l-53l-60l) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
10. Install the fan blade and clutch assembly. Refer to «Fan Clutch Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
11. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 5.3L and 6.0L.
12. Fill the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls 4.3L.
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-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls 4.3L.
4. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls 4.3L.
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-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls 4.3L.
4. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls 4.3L.
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-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls 4.3L.
4. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

J 38185 Hose Clamp Pliers. See Special Tools and Equipment .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
2. Remove the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Remove the clamp at the radiator inlet using the J 38185 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Remove the outlet heater hose (2) from the radiator.
7. Remove the automatic transmission cooler lines. Refer to «Transmission Fluid Cooler Line Quick Connect Fitting»(/chevrolet/chevy-express-g2500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) or «Transmission Fluid Cooler Line Quick Connect Fitting»(/chevrolet/chevy-express-g2500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) in Automatic Transmission.
8. Remove the engine oil cooler lines. Refer to «Engine Oil Cooler Pipe/Hose Quick Connect Fitting»(/chevrolet/chevy-express-g2500/1996-2012/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-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Install the automatic transmission oil cooler lines. Refer to «Transmission Fluid Cooler Line Quick Connect Fitting»(/chevrolet/chevy-express-g2500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) or «Transmission Fluid Cooler Line Quick Connect Fitting»(/chevrolet/chevy-express-g2500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) in Automatic 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 and Equipment»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Install the outlet heater hose (2).
10. Install the outlet heater hose clamp using the J 39529 .
11. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 5.3L, 6.0L or «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g2500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L.
13. Inspect the automatic transmission fluid level. Refer to «Capacities - Approximate Fluid»(/chevrolet/chevy-express-g2500/1996-2012/remont/lubrication-system/#maintenance-and-lubrication__capacities-approximate-fluid) in General Information.
14. Inspect the engine oil level. Refer to «Capacities - Approximate Fluid»(/chevrolet/chevy-express-g2500/1996-2012/remont/lubrication-system/#maintenance-and-lubrication__capacities-approximate-fluid) in General Information.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Disconnect the heater cord from the coolant heater (4).
3. Loosen the coolant heater bolt.
4. Remove the coolant heater from the engine block.
5. Do not score the machined surface of the hole.
6. Grasp the plug with pliers.
7. Pull the plug from the engine block.
8. Clean the core plug hole in order to remove the following substances: Burrs Compound Paint Rough spots

1. Coat the O-ring seal and the cleaned surface of the plug opening with water resistant high-temperature grease lubricant GM P/N 9985164 (Canadian P/N 10953480), or the equivalent.
2. Tightly push the coolant heater (1) into the engine block.
3. Tighten the coolant heater bolt until both of the locking wings draw tightly against the inner wall of the engine block. Tighten: 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»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Inspect the cooling system for leaks.

1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g2500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in 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»(/chevrolet/chevy-express-g2500/1996-2012/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g2500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Disconnect the coolant heater electrical connector (2).
3. Remove the coolant heater cord retainer and bolts.
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 bolts and retainer. Tighten: Tighten the coolant heater cord bolts to 8 N.m (71 lb in).
3. Connect the coolant heater electrical connector (2).
4. 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 system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the coolant does not flow to the radiator until the thermostat opens. This allows the engine to warm quickly.

Cooling Cycle

Coolant 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 two 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 Tester J 38185 Hose Clamp Pliers J 41240 Fan Clutch Remover and Installer

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See also:
• Scan Tool Does Not Power Up
• DTC P0116
• DTC P0116
• Checking Aftermarket Accessories
• Testing for Intermittent Conditions and Poor Connections
• 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
• Circuit Testing
• Connector Repairs
• Lifting and Jacking the Vehicle
• Capacities - Approximate Fluid
• Fastener Notice
• Air Cleaner Outlet Resonator Replacement
• Air Cleaner Assembly Replacement
• Generator Replacement (4.8L, 5.3L, and 6.0L)
• Drive Belt Replacement
• Transmission Fluid Cooler Line Quick Connect Fitting
• Transmission Fluid Cooler Line Quick Connect Fitting
• Symptoms - Engine Cooling
• Diagnostic Trouble Code (DTC) List
• DTC P1258
• Engine Overheating
• Loss of Coolant
• Thermostat Diagnosis
• Coolant Heater Inoperative
• Engine Fails To Reach Normal Operating Temperature
• Cooling System Leak Testing
• Pressure Cap Testing
• Flushing