Engine Cooling System Cadillac Escalade GMT800

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Diagnostic Starting Point - Engine Cooling

Begin the system diagnosis with the DIAGNOSTIC SYSTEM CHECK - ENGINE COOLING . The Diagnostic System Check will provide the following information

1. The identification of the control module(s) which command the system.
2. The ability of the control module(s) to communicate through the serial data circuit.
3. The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check will 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.

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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 Instrument Cluster or Powertrain Control Modules have set DTC's 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.

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Scan Tool Data Definitions

Check Coolant Temp - Range: ON/OFF: This output refers to the commanded state of the Check Coolant Temp message located in the message center. The message will be added to the message center display based on the engine coolant temperature that is sent to the Instrument Cluster as a class 2 message from the PCM. If the engine temperature is greater than 121°C (250°F) the message will be added to the message center, unless the Check Engine Temp message has been added to the message center, and removed when the engine temperature is less than 118°C (245°F).

Check Engine Temp - Range: ON/OFF: This output refers to the commanded state of the Check Engine Temp message located in the message center. The message will be added to the message center display based on the engine coolant temperature that is sent to the Instrument Cluster as a class 2 message from the PCM. If the engine temperature is greater than 128°C (262°F) the message will be added to the message center and removed when the engine temperature is less than 125°C (257°F)

Coolant Level Switch - Range: Low/OK: This parameter indicates when the engine coolant level is low. The scan tool displays Low when the PCM detects the engine coolant level switch is open.

ECT - Range: -40°C to +150°C (-40°F to +302°F): The PCM applies 5.0 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as the engine temperature changes. When the sensor is cold (internal resistance high), the PCM senses a high signal voltage and interprets the voltage as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.

Displayed Coolant Temperature - Range: 32-127°C (89-260°F): This data is the coolant temperature the Instrument Cluster is attempting to display on the coolant temperature gauge. This data may differ from the monitored coolant temperature for a period of time due to filtering. The data may also differ from the monitored coolant temperature when coolant temperature is not in the range of 71-127°C (160-260°F) since the display is limited to these values. If a Class 2 communication failure occurs, this data will be at the minimum value of 32°C (89°F).

Low Coolant - Range: ON/OFF: This output refers to the command state of the Low Coolant message located in the message center. ON is displayed when the Instrument Cluster is commanding the Low Coolant message ON. OFF is displayed when the Instrument Cluster is not commanding the Low Coolant message ON. The Instrument Cluster will display the Low Coolant message when the Instrument Cluster receives a class 2 serial data message from the PCM.

Monitored Coolant Temperature - Range: 40-215°C (40-419°F): This data is the clusters measurement of the engine coolant temperature as provided by the PCM on the Class 2 serial data line.

Reduced Engine Power - Range: ON/OFF: This output refers to the commanded state of the Reduced Engine Power message located in the message center. On is displayed when the Instrument Cluster is commanding the Reduced Engine Power message ON. OFF is displayed when the Instrument Cluster is not commanding the Reduced Engine Power message ON. The Instrument Cluster will display the Reduced Engine Power message when the Instrument Cluster receives a class 2 serial data message from the PCM when the engine temperature reaches 132°C (270°F).

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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 132°C (270°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

1. DTCs P0117, P0118, P1114, and P1115 are not active.
2. The engine is running.

Conditions for Setting the DTC

The engine coolant temperature is above 132°C (270°F) for 10 seconds or more.

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 signal the IPC to turn ON the Service Engine Soon indicator.
3. The PCM will alternately disable two 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.

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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.

Symptoms - Engine Cooling

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to COOLING SYSTEM DESCRIPTION AND OPERATION .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Cooling System. Refer to 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 surge tank reservoir for the proper coolant level.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT 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 Overheated Indicator Always On, See «Engine Overheated Indicator Always On»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
2. Engine Coolant Temperature Indicator Always On, See «Engine Coolant Temperature Indicator Always On»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
3. Low Engine Coolant Indicator Always On, See «Low Engine Coolant Indicator Always On»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
4. Coolant Heater Inoperative, See «Coolant Heater Inoperative»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
5. Engine Overheating, See «Engine Overheating Diagnostic»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
6. Loss of Coolant, See «Loss Of Coolant Diagnostic»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
7. «THERMOSTAT DIAGNOSIS»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis)
8. Engine Fails To Reach Normal Operating Temperature, See «Engine Fails To Reach Normal Operating Temperature»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
9. Fan Clutch Diagnosis, See «Fan Clutch»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)

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Thermostat Diagnosis

Tools Required

J 24731 Tempil-Stick

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). The thermostat should begin to open. J24731 -206 tempil stick melts at 97°C (206°F). 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

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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.

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Pressure Cap Testing

Tools required

1. J 24460-01 Cooling System Pressure Tester
2. J 42401 Radiator Cap / Surge Tank Test Adapter

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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. 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

J 24460-01 Cooling System Pressure Tester

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1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «PRESSURE CAP TESTING»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__pressure-cap-testing) .
3. Wash the pressure cap mating surface with water.
4. Use the J 24460-01 in order to apply pressure to the cooling system. Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gage for any pressure loss.
6. Repair any leaks as required.

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Drain and Fill Procedure

Note. The procedure below must be followed. Improper coolant level could result in a low or high coolant level condition, causing engine damage.

1. Park the vehicle on a level surface.
2. Follow the steps below in order to remove the surge tank fill cap: 2.1. Slowly rotate the cap counterclockwise. 2.2. Stop rotating and allow the hissing to stop. 2.3. After all hissing stops, continue turning counterclockwise in order to remove the cap.
3. Open the radiator drain cock.
4. Allow the system to drain completely.
5. Inspect the engine coolant for the following: Discolored - follow the flush procedure below. Normal in appearance - continue with the next step. NOTE: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months. NOTE: DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.
6. Close the radiator drain cock.
7. Fill the system through the surge tank opening.
8. Pre-mix a 50 to 60 percent solution of DEX-COOL® and clean, drinkable water.
9. Slowly add the pre-mixed solution to the surge tank until the level is slightly above the COLD FILL mark.
10. Start the engine.
11. Idle the engine for 1 minute.
12. Loosely install the surge tank cap. DO NOT allow the system to build up pressure.
13. Cycle the engine from idle to 3,000 RPM in 30 second intervals until the engine coolant reaches 99°C (210°F) and the thermostat opens.
14. Shut off the engine.
15. Refer to step 2 in order to remove the surge tank cap.
16. Start the engine.
17. Idle the engine for 1 minute. Fill the surge tank to 12.7 mm (1/2 in) above the COLD FILL mark on the surge tank.
18. Install the radiator surge tank cap.
19. Cycle the engine from idle to 3,000 RPM in 30 second intervals until the engine coolant reaches 99°C (210°F) and the thermostat opens.
20. Shut off the engine.
21. Top off the coolant, as necessary, to 12.7 mm (1/2 in) above the COLD FILL mark on the surge tank.
22. Rinse away any excess coolant from the engine and the engine compartment.
23. Inspect the concentration of the coolant.

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1. Drain the cooling system, refer to the above procedure.
2. If equipped with the 4.8L, 5.3L or 6.0L engine, remove the left and right engine block coolant drain plugs
3. If equipped with the 8.1L engine, remove the left and right engine block coolant drain plugs.
4. Remove the engine block coolant heater, if equipped. Refer to «COOLANT HEATER REPLACEMENT (DEALER INSTALLATION - 6.0L ENGINE)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «COOLANT HEATER REPLACEMENT (4.8L, 5.3L, AND 6.0L ENGINES)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «COOLANT HEATER REPLACEMENT (8.1L ENGINE)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Allow the engine block to drain completely.
6. Apply sealant GM P/N 12346004 (Canadian P/N 10953480) or equivalent to the drain plugs. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
7. Reinstall the engine block coolant drain plugs. Tighten Tighten the 4.8L, 5.3L or 6.0L engine block coolant drain plug to 60 N.m (44 lb ft). Tighten the 8.1L engine block coolant drain plug to 60 N.m (44 lb ft).
8. Install the engine block coolant heater, if equipped. Refer to «COOLANT HEATER REPLACEMENT (DEALER INSTALLATION - 6.0L ENGINE)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «COOLANT HEATER REPLACEMENT (4.8L, 5.3L, AND 6.0L ENGINES)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «COOLANT HEATER REPLACEMENT (8.1L ENGINE)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Fill the cooling system, refer to the above procedure.

Flushing

Important

1. Do not use a chemical flush.
2. Store used coolant in the proper manner, such as in a used engine coolant holding tank. Do not pour used coolant down a drain. Ethylene glycol antifreeze is a very toxic chemical. Do not dispose of coolant into the sewer system or ground water. This is illegal and ecologically unsound.
3. Various methods and equipment can be used to flush the cooling system. If special equipment is used (such as a back flusher) follow the manufacturer's instructions. However, always remove the thermostat before back flushing the system.

1. Block the drive wheels.
2. Place the transmission in park (P) or neutral (N).
3. Engage the park brake.
4. Run the engine until the thermostat opens.
5. Stop the engine.
6. Follow the drain and fill procedure using only clean drinkable water. Repeat the procedure if necessary, until the fluid is nearly colorless. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
7. Fill the coolant reservoir to the FULL HOT mark.
8. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Radiator Cleaning

Note. The radiator fins are necessary for good heat transfer. Do not brush the fins. This may cause damage to the fins, reducing heat transfer.

Important: Remove bugs, leaves, dirt and other debris by blowing compressed air through the engine side of the radiator.

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

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the air cleaner assembly.
3. Remove the surge tank overflow hose from the surge tank.
4. Disconnect the low coolant level switch electrical connector (3).
5. Reposition the surge tank inlet hose clamp.
6. Remove the surge tank inlet (1) hose from the surge tank.
7. Reposition the surge tank outlet hose clamp.
8. Remove the surge tank outlet hose (2) from the surge tank.
9. Remove the bolt from the surge tank.
10. Remove the nut from the surge tank.
11. Remove the surge tank.

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1. Install the surge tank. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the bolt to the surge tank. Tighten Tighten the bolt to 9 N.m (80 lb in).
3. Install the nut to the surge tank. Tighten Tighten the nut to 9 N.m (80 lb in).
4. Install the surge tank outlet hose (2) to the surge tank.
5. Position the surge tank outlet hose clamp.
6. Install the surge tank inlet hose (1) to the surge tank.
7. Position the surge tank inlet hose clamp.
8. Connect the low coolant level switch electrical connector (3).
9. Install the surge tank overflow hose.
10. Install the air cleaner assembly.
11. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the surge tank inlet hose clamp from the radiator.
3. Remove the surge tank inlet hose from the radiator.
4. Reposition the surge tank inlet hose clamp at the surge tank.
5. Remove the surge tank inlet hose (1) from the surge tank.

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1. Install the surge tank inlet hose (1) to the surge tank.
2. Position the surge tank inlet hose clamp to the surge tank.
3. Install the surge tank inlet hose to the radiator.
4. Position the surge tank inlet hose clamp to the radiator.
5. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Surge Tank Hose/Pipe Replacement - Outlet (4.8L, 5.3L, and 6.0L Engines)

Tools Required

J 43181 Heater Line Quick Connect Release Tool

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the air cleaner outlet duct.
4. If equipped without regular production option (RPO) C36 auxiliary heater, remove the surge tank/heater outlet hose (1) from the mounting clip.
5. If equipped with RPO C36 auxiliary heater, remove the surge tank/heater outlet hose (1) from the mounting clip.
6. Install the J 43181 to the surge tank outlet hose (black connector).
7. Close the J 43181 around the surge tank outlet hose.
8. Firmly pull the J 43181 into the quick connect end of the outlet hose.
9. If equipped without RPO C36 auxiliary heater, firmly grasp the outlet hose. Pull the outlet hose in order to disengage the hose from the heater and blower module.
10. If equipped with RPO C36 auxiliary heater, firmly grasp the outlet hose. Pull the outlet hose in order to disengage the hose from the heater and blower module.
11. Reposition the surge tank outlet hose clamp at the surge tank.
12. Remove the surge tank outlet hose (2) from the surge tank.
13. Reposition the surge tank outlet hose clamp at the water pump.
14. Remove the surge tank outlet hose from the water pump.
15. Remove the surge tank outlet hose.

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1. Install the surge tank outlet hose.
2. Install the surge tank outlet hose to the water pump.
3. Position the surge tank outlet hose clamp to the water pump.
4. Install the surge tank outlet hose (2) to the surge tank.
5. Position the surge tank outlet hose clamp to the surge tank.
6. If equipped with RPO C36 auxiliary heater, connect the surge tank outlet hose to the heater and blower module.
7. If equipped without RPO C36 auxiliary heater, connect the surge tank outlet hose to the heater and blower module. Firmly push the hose onto the heater and blower module pipe until an audible click is heard.
8. If equipped with RPO C36 auxiliary heater, install the surge tank/heater outlet hose (1) to the mounting clip.
9. If equipped without RPO C36 auxiliary heater, install the surge tank/heater outlet hose (1) to the mounting clip.
10. Install the air cleaner outlet duct.
11. Align the arrow at the throttle body end of the duct with the throttle body attaching stud. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
12. Tighten the air cleaner outlet duct clamps at the following locations: Throttle body MAF/IAT sensor Tighten Tighten the clamps to 7 N.m (62 lb in).
13. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

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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).

Installation Procedure

Important: Do not install the retaining ring (3) onto the fitting by pushing the retaining ring down over the fitting.

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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.

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the air cleaner outlet duct.
4. If necessary, remove the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, AND 6.0L (RPO LQ4)»(ref-180687-S32663973432005072800000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L (RPO LQ9)»(ref-180687-S12210361512005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
5. Remove the radiator vent inlet hose from the radiator inlet hose clips.
6. Reposition the inlet hose clamp from the radiator.
7. Remove the inlet hose from the radiator.
8. Remove the inlet hose clip from the fan shroud.
9. Reposition the inlet hose clamp from the water outlet.
10. Remove the inlet hose from the water outlet.

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1. Install the inlet hose to the water outlet.
2. Reposition the inlet hose clamp to the water outlet.
3. Install the inlet hose clip to the fan shroud.
4. Install the inlet hose to the radiator.
5. Reposition the inlet hose clamp to the radiator.
6. Install the radiator vent inlet hose to the radiator inlet hose clips.
7. If necessary, install the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, AND 6.0L (RPO LQ4)»(ref-180687-S32663973432005072800000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L (RPO LQ9)»(ref-180687-S12210361512005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L. Important: Align the arrow at the throttle body end of the duct with the throttle body attaching stud.
8. Install the air cleaner outlet duct. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
9. Tighten the air cleaner outlet duct clamps at the following locations: Throttle body MAF/IAT sensor Tighten Tighten the air cleaner outlet duct clamp screws to 7 N.m (62 lb in).
10. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the inlet hose clamp from the radiator.
3. Remove the inlet hose from the radiator.
4. Reposition the inlet hose clamp from the water outlet.
5. Remove the inlet hose from the water outlet.

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1. Install the inlet hose to the water outlet.
2. Reposition the inlet hose clamp to the water outlet.
3. Install the inlet hose to the radiator.
4. Reposition the inlet hose clamp to the radiator.
5. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the air cleaner outlet duct.
4. Reposition the outlet hose clamp from the water pump.
5. Remove the outlet hose from the water pump.
6. Reposition the outlet hose clamp from the radiator.
7. Remove the outlet hose from the radiator.

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1. Install the outlet hose to the radiator.
2. Reposition the outlet hose clamp to the radiator.
3. Install the outlet hose to the water pump.
4. Reposition the outlet hose clamp to the water pump. Important: Align the arrow at the throttle body end of the duct with the throttle body attaching stud.
5. Install the air cleaner outlet duct.
6. Install the radiator inlet hose clip to the outlet duct. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
7. Tighten the air cleaner outlet duct clamps at the following locations: Throttle body MAF/IAT sensor Tighten Tighten the air cleaner outlet duct clamp screws to 7 N.m (62 lb in).
8. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 83

Scheme 84

Scheme 85

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the radiator outlet hose from the radiator. Refer to «RADIATOR HOSE QUICK CONNECT FITTING»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Reposition the surge tank outlet hose clamp from the surge tank.
4. Remove the surge tank outlet hose (2) from the surge tank.
5. Reposition the outlet hose clamp from the water pump.
6. Remove the outlet hose from the water pump.

Scheme 86

Scheme 87

Scheme 88

1. Install the outlet hose to the water pump.
2. Reposition the outlet hose clamp to the water pump.
3. Install the surge tank outlet hose (2) to the surge tank.
4. Reposition the surge tank outlet hose clamp to the surge tank.
5. Install the radiator outlet hose to the radiator. Refer to «RADIATOR HOSE QUICK CONNECT FITTING»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 89

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the vent inlet hose clamp from the radiator.
3. Remove the vent inlet hose from the radiator.
4. Reposition the vent inlet hose clamp from the surge tank.
5. Remove the vent inlet hose from the surge tank.

Scheme 90

1. Install the vent inlet hose to the surge tank.
2. Reposition the vent inlet hose clamp to the surge tank.
3. Install the vent inlet hose to the radiator.
4. Reposition the vent inlet hose clamp to the radiator.
5. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 91

Scheme 92

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.

Important: When performing the following procedure, do not reuse the old retaining rings. Replace the old retaining rings with new ones.

Do not install the new retaining ring onto the fitting by pushing the retaining ring down over the fitting.

Scheme 93

Scheme 94

Scheme 95

Scheme 96

Scheme 97

Scheme 98

Scheme 99

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. Important: Do not manually depress the retaining clip when installing the plastic cap.
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.

Removal Procedure

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.

Scheme 100

Scheme 101

Scheme 102

Scheme 103

Scheme 104

Scheme 105

Scheme 106

1. Disengage the plastic caps from the quick connect fittings. Pull the caps back along the pipe.
2. Hold one leg of the retaining clip.
3. Using a small pick-type tool or bent screwdriver, gently pry the other end of the retaining clip from the quick connect fitting.
4. Rotate the retaining clip out of the quick connect fitting. Remove the retaining clip completely.
5. Discard the OLD retaining clip.
6. If equipped with a 6.0L engine, perform the following: 6.1. Open the oil cooler hose clip located on the lower fan shroud. 6.2. Remove the oil cooler hoses from the clip. 6.3. Gently pull the oil cooler pipe fittings straight out from the radiator quick connect fittings. 6.4. Raise and suitably support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__lifting-and-jacking-the-vehicle) in General Information.
7. Remove the exhaust manifold pipe nuts.
8. Reposition the pipe out of the way.
9. If equipped with a 8.1L engine, perform the following: 9.1. Remove the oil cooler hoses from the clip. 9.2. Gently pull the oil cooler pipe fittings straight out from the radiator quick connect fittings. 9.3. Raise and suitably support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__lifting-and-jacking-the-vehicle) in General Information.
10. If equipped, remove the engine shield bolts.
11. Remove the engine shield.
12. If equipped with a 6.0L engine, perform the following: 12.1. Remove the oil cooler hose bracket bolt (1). 12.2. Remove the oil cooler hose adapter bolts (2). 12.3. Remove the oil cooler hose assembly and gasket. Discard the gasket. 12.4. Inspect the fittings, connectors and cooler hoses for damage or distortion.
13. If equipped with a 8.1L engine, perform the following: 13.1. Remove the oil cooler hose bracket bolt. 13.2. Disconnect the quick connect fittings (1) at the engine. 13.3. Remove the oil cooler hose assembly. Discard the gasket. 13.4. Inspect the fittings, connectors and cooler hoses for damage or distortion.

Important: A distinct snap should be heard when assembling the tube ends of the hose assembly to quick connectors. To ensure the tube is fully inserted into the connector, check by giving the tube a forceful pull.

Scheme 107

Scheme 108

Scheme 109

Scheme 110

Scheme 111

Scheme 112

Scheme 113

Scheme 114

Scheme 115

Scheme 116

Scheme 117

1. If equipped with a 8.1L engine, perform the following: 1.1. Remove the oil cooler hose assembly. 1.2. Connect the quick connect fittings (1) at the engine. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices. 1.3. Install the oil cooler hose bracket bolt. Tighten Tighten the bolt to 50 N.m (37 lb ft).
2. If equipped with a 6.0L engine, perform the following: 2.1. Install the oil cooler hose assembly and a new gasket. 2.2. Install the oil cooler hose adapter bolts (2). Tighten Tighten the bolts to 12 N.m (106 lb in). 2.3. Install the oil cooler hose bracket bolt (1). Tighten Tighten the bolt to 25 N.m (18 lb ft).
3. If equipped, install the engine shield.
4. Install the engine shield bolts. Tighten Tighten the bolts to 20 N.m (15 lb ft).
5. Do not install the new retaining clip onto the fitting by pushing on the clip. Important: Failure to properly install the retaining clip could cause the cooler line to come loose and cause damage to the engine.
6. Install the NEW retaining clip into the quick connect fitting by using your thumb and forefinger. Insert the new retaining clip into one of the three fitting recesses. Ensure that the retaining clip is engaged in all 3 slots.
7. With one end of the retaining clip engaged in the connector fitting slot, use your thumb in order to rotate the retaining clip around the connector fitting, until the retaining clip snaps into place.
8. Ensure that the 3 retaining clip ears are seen from inside the fitting and that the retaining clip moves freely in the fitting slots.
9. Install a new retaining clip into the remaining quick connect fitting.
10. Install the pipe to the exhaust manifold.
11. Install the exhaust manifold pipe nuts. Tighten Tighten the nuts to 50 N.m (37 lb ft).
12. Lower the vehicle.
13. If equipped with a 6.0L engine, perform the following: 13.1. Install the oil cooler hoses to the hose clip on the fan shroud. 13.2. Snap the oil cooler hose clip shut. Important: Ensure the oil cooler line being installed has a plastic cap on the end that connects to the quick connect fitting. If no plastic cap exists, or the plastic cap is damaged, obtain a new cap. Install the cap onto the cooler line prior cooler line installation. Do not use the plastic cap in order to install the cooler line into the fitting.
14. If equipped with a 8.1L engine perform the following: 14.1. Install the oil cooler hoses to the clip. 14.2. Install the oil cooler lines to the radiator. Install the cooler line straight into the quick connect fitting. Insert the cooler line end into the quick connect fitting until a click is either heard or felt. 14.3. Pull back sharply on the cooler line in order to ensure that the cooler line is installed in the quick connect fitting. Important: Do not manually depress the retaining clip when installing the plastic cap.
15. Snap the plastic cap onto the quick connect fitting.
16. Ensure that the plastic cap is fully seated against the fitting.
17. Ensure that no gap is present between the cap and the fitting.

Fan Replacement

Tools Required

1. J 46406 Fan Clutch Remover and Installer
2. J 41240-5A Fan Clutch Wrench

Scheme 118

Scheme 119

Scheme 120

1. Remove the upper fan shroud. Refer to «FAN SHROUD REPLACEMENT - UPPER (W/O M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «FAN SHROUD REPLACEMENT - UPPER (W/M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Install the J 46406 and the J 41240-5A to the fan clutch.
3. Remove the fan hub nut from the water pump in a counterclockwise rotation.
4. Lay the fan blade face down on a workbench.
5. Remove the fan clutch bolts from the rear of the fan blade, if necessary.
6. Separate the fan clutch from the fan blade.

Scheme 121

Scheme 122

Scheme 123

1. Install the fan clutch bolts.
2. Install the fan clutch onto the fan blade, if necessary. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
3. Install the fan clutch bolts. Tighten Tighten the bolts to 23 N.m (17 lb ft).
4. Install the fan blade.
5. Install the J 46406 and the J 41240-5A to the fan clutch. Tighten Tighten the fan clutch nut clockwise to 56 N.m (41 lb ft).
6. Install the upper fan shroud. Refer to «FAN SHROUD REPLACEMENT - UPPER (W/O M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «FAN SHROUD REPLACEMENT - UPPER (W/M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Fan Clutch Replacement

Tools Required

1. J 46406 Fan Clutch Remover and Installer
2. J 41240-5A Fan Clutch Wrench

Scheme 124

Scheme 125

Scheme 126

1. Remove the upper fan shroud. Refer to «FAN SHROUD REPLACEMENT - UPPER (W/O M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «FAN SHROUD REPLACEMENT - UPPER (W/M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Install the J 46406 and the J 41240-5A to the fan clutch.
3. Remove the fan hub nut from the water pump in a counterclockwise rotation.
4. Lay the fan blade face down on a workbench.
5. Remove the fan clutch bolts from the rear of the fan blade.
6. Separate the fan clutch from the fan blade.

Scheme 127

Scheme 128

Scheme 129

1. Install the fan clutch bolts.
2. Install the fan clutch onto the fan blade. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
3. Install the fan clutch bolts. Tighten Tighten the bolts to 23 N.m (17 lb ft).
4. Install the fan blade.
5. Install the J 46406 and the J 41240-5A to the fan clutch. Tighten Tighten the fan clutch nut clockwise to 56 N.m (41 lb ft).
6. Install the upper fan shroud. Refer to «FAN SHROUD REPLACEMENT - UPPER (W/O M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «FAN SHROUD REPLACEMENT - UPPER (W/M74)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Important: The thermostat is not serviceable separately. The thermostat housing (water pump inlet) and thermostat must be replaced as an assembly.

Scheme 130

1. Remove the radiator outlet hose. Refer to «RADIATOR HOSE REPLACEMENT - OUTLET (4.8L, 5.3L, AND 6.0L ENGINES)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «RADIATOR HOSE REPLACEMENT - OUTLET (8.1L ENGINE)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the water pump inlet bolts.
3. Remove the water pump inlet from the water pump.

Scheme 131

1. Install the water pump inlet to the water pump. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the water pump inlet bolts. Tighten Tighten the bolts to 15 N.m (11 lb ft).
3. Install the radiator outlet hose. Refer to «RADIATOR HOSE REPLACEMENT - OUTLET (4.8L, 5.3L, AND 6.0L ENGINES)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) or «RADIATOR HOSE REPLACEMENT - OUTLET (8.1L ENGINE)»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 132

Scheme 133

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the inlet hose clamp at the water outlet.
3. Remove the inlet hose from the water outlet.
4. Remove the water outlet bolts (2).
5. Remove the water outlet (1).
6. Remove the thermostat (3).

Scheme 134

Scheme 135

1. Install the thermostat (3).
2. Install the water outlet (1). NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
3. Install the water outlet bolts (2). Tighten Tighten the bolts to 30 N.m (22 lb ft).
4. Install the inlet hose to the water outlet.
5. Position the inlet hose clamp at the water outlet.
6. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 136

Scheme 137

Scheme 138

Scheme 139

Scheme 140

Scheme 141

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the drive belt tensioner. Refer to «DRIVE BELT TENSIONER REPLACEMENT -- ACCESSORY»(ref-180687-S30455948342005072800000) in Engine Mechanical - 8.1 L.
3. Position the inlet hose clamp at the water crossover.
4. Remove the inlet hose from the water crossover.
5. Position the heater inlet hose clamp at the water crossover.
6. Remove the heater inlet hose from the water crossover.
7. Position the bypass hose clamps at the water crossover and water pump.
8. Remove the bypass hose.
9. Remove the generator. Refer to GENERATOR REPLACEMENT (4.8L, 5.3L, AND 6.0L ENGINES) or GENERATOR REPLACEMENT (8.1L ENGINE) in Engine Electrical.
10. Remove the power steering pump. Refer to POWER STEERING PUMP REPLACEMENT (4.8L, 5.3L AND 6.0L) or POWER STEERING PUMP REPLACEMENT (8.1L) in Power Steering System.
11. Remove the generator bracket bolts and nut.
12. Remove the generator bracket stud.
13. Remove the generator bracket.
14. Remove the water crossover bolts.
15. Remove the water crossover.
16. Remove and discard the water crossover gaskets.
17. If replacing the water crossover remove the following: 17.1. Water outlet bolts (2) 17.2. Water outlet (1) 17.3. Thermostat (3)

Note. Refer to FASTENER NOTICE in Cautions and Notices.

Scheme 142

Scheme 143

Scheme 144

Scheme 145

Scheme 146

Scheme 147

1. If replacing the water crossover install the following: 1.1. Thermostat (3) 1.2. Water outlet (1) 1.3. Water outlet bolts (2) Tighten Tighten the bolts to 30 N.m (22 lb ft).
2. Install NEW water crossover gaskets.
3. Install the water crossover.
4. Install the water crossover bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
5. Install the generator bracket.
6. Install the generator bracket stud. Tighten Tighten the stud to 20 N.m (15 lb ft).
7. Install the generator bracket bolts and nut. Tighten Tighten the bolts and nut to 50 N.m (37 lb ft).
8. Install the power steering pump. Refer to POWER STEERING PUMP REPLACEMENT (4.8L, 5.3L AND 6.0L) or POWER STEERING PUMP REPLACEMENT (8.1L) in Power Steering System.
9. Install the generator. Refer to GENERATOR REPLACEMENT (4.8L, 5.3L, AND 6.0L ENGINES) or GENERATOR REPLACEMENT (8.1L ENGINE) in Engine Electrical.
10. Install the bypass hose.
11. Position the bypass hose clamps at the water crossover and water pump.
12. Install the heater inlet hose to the water crossover.
13. Position the heater inlet hose clamp at the water crossover.
14. Install the inlet hose to the water crossover.
15. Position the inlet hose clamp at the water crossover.
16. Install the drive belt tensioner. Refer to «DRIVE BELT TENSIONER REPLACEMENT -- ACCESSORY»(ref-180687-S30455948342005072800000) in Engine Mechanical - 8.1 L.
17. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 148

Scheme 149

Scheme 150

Scheme 151

1. Remove the intake manifold. Refer to «INTAKE MANIFOLD REPLACEMENT»(ref-180687-S30099749752005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
2. Remove the coolant air bleed pipe studs (1).
3. Remove the coolant air bleed pipe (2) with gaskets (3).
4. Remove the coolant air bleed pipe cover bolts (1) and covers (2).
5. Remove the gaskets from the coolant air bleed pipe and covers.
6. Discard the gaskets.
7. Remove the coolant air bleed hose (1) from the pipe (2).

Scheme 152

Scheme 153

Scheme 154

Scheme 155

1. Install the coolant air bleed hose (1) onto the pipe (2) Important: Install the gaskets properly onto the pipe and covers. Position the O-ring seal onto the nipple portion of the pipe.
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. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
4. Install the coolant air bleed pipe studs (1). Tighten Tighten the studs to 12 N.m (106 lb in).
5. Install the coolant air bleed pipe covers (2) and bolts (1). Tighten Tighten the bolts to 12 N.m (106 lb in).
6. Install the intake manifold. Refer to «INTAKE MANIFOLD REPLACEMENT»(ref-180687-S30099749752005072800000) on page in Engine Mechanical - 4.8L, 5.3L, and 6.0L.

Scheme 156

Scheme 157

1. If necessary, remove the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, AND 6.0L (RPO LQ4)»(ref-180687-S32663973432005072800000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L (RPO LQ9)»(ref-180687-S12210361512005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
2. Position the coolant air bleed hose clamp at the throttle body.
3. Remove the coolant air bleed hose from the throttle body.
4. Position the hose clamp at the pipe.
5. Remove the coolant air bleed hose (1) from the pipe (2).

Scheme 158

Scheme 159

1. Install the coolant air bleed hose (1) to the pipe (2).
2. Position the 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. If necessary, install the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, AND 6.0L (RPO LQ4)»(ref-180687-S32663973432005072800000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L (RPO LQ9)»(ref-180687-S12210361512005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
6. Add engine coolant, if necessary.

Scheme 160

Scheme 161

Scheme 162

Scheme 163

Scheme 164

Scheme 165

Scheme 166

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the radiator inlet hose clip from the outlet duct.
4. Remove the air cleaner outlet duct.
5. If necessary, remove the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, AND 6.0L (RPO LQ4)»(ref-180687-S32663973432005072800000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L (RPO LQ9)»(ref-180687-S12210361512005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
6. Remove the radiator vent inlet hose from the radiator hose clips.
7. Position the inlet hose clamp at the water pump.
8. Remove the inlet hose from the water pump.
9. Remove the fan blade. Refer to «FAN REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement)
10. Remove the accessory drive belt. Refer to «DRIVE BELT REPLACEMENT -- ACCESSORY»(ref-180687-S16348846492005072800000) in Engine Mechanical -4.8L, 5.3L, and 6.0L.
11. Position the outlet hose clamp at the water pump.
12. Remove the outlet hose from the water pump.
13. Position the surge tank outlet hose clamp at the water pump.
14. Remove the surge tank outlet hose from the water pump.
15. Position the heater inlet hose clamp at the water pump.
16. Remove the heater inlet hose from the water pump.
17. Remove the water pump bolts.
18. Remove the water pump and gaskets.
19. Discard the water pump gaskets

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

Scheme 167

Scheme 168

Scheme 169

Scheme 170

Scheme 171

Scheme 172

Scheme 173

Scheme 174

1. Install the water pump and NEW gaskets. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the water pump bolts. Tighten 2.1. Tighten the bolts a first pass to 15 N.m (11 lb ft). 2.2. Tighten the 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 surge tank outlet hose to the water pump.
6. Position the surge tank outlet hose clamp at the water pump.
7. Install the outlet hose to the water pump.
8. Position the outlet hose clamp at the water pump.
9. Install the accessory drive belt. Refer to «DRIVE BELT REPLACEMENT -- ACCESSORY»(ref-180687-S16348846492005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0L.
10. Install the fan blade. Refer to «FAN REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement) .
11. Install the inlet hose to the water pump.
12. Position the inlet hose clamp at the water pump.
13. Install the engine vent inlet hose to the radiator hose clips.
14. If necessary, install the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, AND 6.0L (RPO LQ4)»(ref-180687-S32663973432005072800000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L (RPO LQ9)»(ref-180687-S12210361512005072800000) in Engine Mechanical - 4.8L, 5.3L, and 6.0 L.
15. Install the air cleaner outlet duct.
16. Align the arrow at the throttle body end of the duct with the throttle body attaching stud.
17. Install the radiator inlet hose clip to the outlet duct.
18. Tighten the air cleaner outlet duct clamps at the following locations: Throttle body MAF/IAT sensor Tighten Tighten the clamps to 7 N.m (62 lb in).
19. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 175

Scheme 176

Scheme 177

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system)
2. Remove the drive belt. Refer to «DRIVE BELT REPLACEMENT -- ACCESSORY»(ref-180687-S16348846492005072800000) in Engine Mechanical - 8.1 L.
3. Remove the fan clutch. Refer to «FAN CLUTCH REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__fan-clutch-replacement) .
4. Position the outlet hose clamp at the water pump.
5. Remove the outlet hose from the water pump.
6. Position the bypass hose clamps at the water pump and water crossover.
7. Remove the bypass hose.
8. Remove the water pump bolts.
9. Remove the water pump.
10. Remove and discard the water pump gaskets.

Scheme 178

Scheme 179

Scheme 180

1. Place NEW water pump gaskets into place.
2. Install the water pump. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
3. Install the water pump bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
4. Install the bypass hose.
5. Position the bypass hose clamps at the water pump and water crossover.
6. Install the outlet hose to the water pump.
7. Position the outlet hose clamp at the water pump.
8. Install the fan clutch. Refer to «FAN CLUTCH REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__fan-clutch-replacement) .
9. Install the drive belt. Refer to «DRIVE BELT REPLACEMENT -- ACCESSORY»(ref-180687-S16348846492005072800000) in Engine Mechanical - 8.1 L.
10. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 181

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the radiator drain cock.

Scheme 182

1. Install the radiator drain cock.
2. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 183

Scheme 184

Scheme 185

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

Scheme 186

Scheme 187

Scheme 188

1. Install the upper fan shroud. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the fan shroud bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
3. Install the fan shroud retainers.
4. If equipped install the inlet radiator hose retainer to the fan shroud
5. If equipped install the throttle body heater hose retainer to the fan shroud.
6. Install the air cleaner outlet duct.
7. Tighten the air cleaner outlet duct clamp at the throttle body. Tighten Tighten the clamp screw to 7 N.m (62 lb in).
8. Tighten the air cleaner outlet duct clamp at the mass airflow sensor. Tighten Tighten the clamp screw to 7 N.m (62 lb in).

Scheme 189

Scheme 190

Scheme 191

Scheme 192

Scheme 193

Scheme 194

1. Loosen the air cleaner outlet duct clamps from the throttle body.
2. Loosen the air cleaner outlet duct clamps from the mass airflow sensor.
3. Remove the air cleaner outlet duct.
4. Remove the A/C line retainer from the fan shroud.
5. Remove the engine harness clip from the PCM cover.
6. Remove the TCM cover bolts.
7. Remove TCM cover from the fan shroud.
8. Loosen the TCM electrical connector bolts.
9. Disconnect the TCM electrical connectors (1).
10. Remove the TCM and cover.
11. Remove the fan shroud retainers.
12. Remove the fan shroud bolts
13. Remove the upper fan shroud.

Scheme 195

Scheme 196

Scheme 197

Scheme 198

Scheme 199

Scheme 200

1. Install the upper fan shroud. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices
2. Install the fan shroud bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
3. Install the fan shroud retainers.
4. Connect the TCM electrical connectors (1).
5. Install the TCM and cover.
6. Tighten the TCM electrical connector bolts. Tighten Tighten the bolts to 8 N.m (71 lb in)
7. Install the TCM cover to the fan shroud.
8. Install the TCM cover bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
9. Install the engine harness clip to the PCM cover.
10. Install the A/C line retainer to the fan shroud.
11. Install the air cleaner outlet duct.
12. Tighten the air cleaner outlet duct clamp at the throttle body. Tighten Tighten the clamp screws to 7 N.m (62 lb in).
13. Tighten the air cleaner outlet duct clamp at the mass airflow sensor. Tighten Tighten the clamp screws to 7 N.m (62 lb in).

Scheme 201

1. Remove the cooling fan. Refer to «FAN REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement) .
2. If equipped with engine oil cooler, remove the oil cooler hose clip from the lower fan shroud.
3. Lift the lower fan shroud up in order to disengage the fan shroud from the retaining clips on the radiator.

Scheme 202

1. Install the lower fan shroud to the retaining clips on the radiator and firmly push down.
2. If equipped with the engine oil cooler, Install the oil cooler hose clip to the lower fan shroud.
3. Install the cooling fan. Refer to «FAN REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system__fan-replacement) .

Scheme 203

Scheme 204

Scheme 205

1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Position the inlet hose clamp from the radiator.
3. Remove the inlet hose from the radiator.
4. Position the outlet hose clamp from the radiator.
5. Remove the radiator outlet hose from the radiator.
6. Remove the lower fan shroud. Refer to «FAN SHROUD REPLACEMENT - LOWER»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Position the radiator vent inlet hose clamp from the radiator.
8. Remove the vent inlet hose from the radiator.
9. Remove the engine oil cooler lines from the radiator. Refer to «ENGINE OIL COOLER PIPE/HOSE QUICK CONNECT FITTING»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
10. Remove the transmission oil cooler lines from the radiator. Refer to TRANSMISSION OIL COOLER LINE QUICK CONNECT FITTING in Transmission 4L80E or TRANSMISSION OIL COOLER LINE QUICK CONNECT FITTING in Transmission 4L60E.
11. Remove the radiator bolts.
12. Remove the radiator from the vehicle.

Scheme 206

Scheme 207

1. Install the radiator to the vehicle. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the radiator bolts. Tighten Tighten the bolts to 25 N.m (18 lb ft).
3. Install the engine oil cooler lines to the radiator. Refer to «ENGINE OIL COOLER PIPE/HOSE QUICK CONNECT FITTING»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Install the transmission oil cooler lines to the radiator. Refer to TRANSMISSION OIL COOLER LINE QUICK CONNECT FITTING in Transmission 4L80E or TRANSMISSION OIL COOLER LINE QUICK CONNECT FITTING in Transmission 4L60E.
5. Install the radiator vent inlet hose to the radiator.
6. Reposition the radiator vent inlet hose clamp to the radiator.
7. Install the lower fan shroud. Refer to «FAN SHROUD REPLACEMENT - LOWER»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
8. Install the outlet hose to the radiator.
9. Reposition the outlet hose clamp to the radiator.
10. Install the inlet hose to the radiator.
11. Reposition the inlet hose clamp to the radiator.
12. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 208

1. Remove the radiator. Refer to «RADIATOR REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the radiator air baffle retainers.
3. Remove the radiator air baffles.

Scheme 209

1. Install the radiator air baffles.
2. Install the radiator air baffle retainers.
3. Install the radiator. Refer to «RADIATOR REPLACEMENT»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 210

1. Remove the radiator air upper baffle retainers.
2. Remove the radiator air upper baffle.

Scheme 211

1. Install the radiator air upper baffle.
2. Install the radiator air upper baffle retainers.

Scheme 212

Scheme 213

Scheme 214

Scheme 215

Scheme 216

Scheme 217

Scheme 218

1. Drain the cooling system/engine block. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and suitably support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__lifting-and-jacking-the-vehicle) in General Information.
3. Remove the oil pan skid plate bolts and plate.
4. Remove the oil cooler hose bracket bolt.
5. Remove the oil cooler hose adapter bolts.
6. Remove and discard the oil cooler hose adapter gasket.
7. Position the oil cooler hose adapter end out of the way. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
8. Install the coolant heater in place of the drain plug. Tighten Tighten the coolant heater to 50 N.m (37 lb ft).
9. Push the engine coolant heater cord electrical connector (2) firmly into the coolant heater (1). Important: The engine coolant heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Always keep the electrical cord neatly rolled up with the end of the cord tucked in the center of the coil and secured in place.
10. Place the cord into position.
11. Install the heater cord bolt and retainer. Tighten Tighten the bolt to 8 N.m (71 lb in).
12. Position the oil cooler hose adapter.
13. Install a NEW oil cooler hose adapter gasket.
14. Install the oil cooler hose adapter bolts. Tighten Tighten the bolts to 12 N.m (106 lb in).
15. Install the oil cooler hose bracket bolt. Tighten Tighten the bolt to 25 N.m (18 lb ft).
16. Install the oil pan skid plate and bolts. Tighten Tighten the bolts to 20 N.m (15 lb ft).
17. Lower the vehicle.
18. Fill the cooling system/engine block. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 219

Scheme 220

Scheme 221

Scheme 222

1. Drain the cooling system/engine block. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and suitably support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__lifting-and-jacking-the-vehicle) in General Information.
3. Remove the oil pan skid plate bolts and plate.
4. Remove the oil cooler hose bracket bolt.
5. Remove the oil cooler hose adapter bolts.
6. Remove and discard the oil cooler hose adapter gasket.
7. Position the oil cooler hose adapter end out of the way.
8. Disconnect the coolant heater electrical connector (2). Important: Do not score the surface of the engine block hole when removing the coolant heater.
9. Remove the coolant heater from the engine block.
10. Remove any burrs, sealer, or other rough spots.

Scheme 223

Scheme 224

Scheme 225

Scheme 226

1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
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. Position the oil cooler hose adapter end.
5. Install a NEW oil cooler hose adapter gasket.
6. Install the oil cooler hose adapter bolts. Tighten Tighten the bolts to 12 N.m (106 lb in).
7. Install the oil cooler hose bracket bolt. Tighten Tighten the bolt to 25 N.m (18 lb ft).
8. Install the oil pan skid plate and bolts. Tighten Tighten the bolts to 20 N.m (15 lb ft).
9. Lower the vehicle.
10. Fill the cooling system/engine block. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 227

Scheme 228

Scheme 229

1. Drain the cooling system/engine block. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and suitably support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__lifting-and-jacking-the-vehicle) in General Information.
3. Remove the oil pan skid plate bolts and plate.
4. Disconnect the coolant heater electrical connector.
5. Remove the coolant heater from the engine block.

Scheme 230

Scheme 231

1. If reusing the old coolant heater, apply sealant GM P/N 12346004, (Canadian P/N 10953480), or equivalent to the threads. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the coolant heater into the engine block. Tighten Tighten the coolant heater to 60 N.m (40 lb ft). 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.
3. Connect the coolant heater electrical connector.
4. Fill the cooling system/engine block. Refer to «DRAINING AND FILLING COOLING SYSTEM»(/cadillac/escalade/gmt800-2001-2006/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 232

Scheme 233

1. Raise and suitably support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__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.

Scheme 234

Scheme 235

1. Install the coolant heater cord. NOTE: Refer to «FASTENER NOTICE»(/cadillac/escalade/gmt800-2001-2006/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) in Cautions and Notices.
2. Install the coolant heater cord bolts and retainer. Tighten Tighten the bolts to 8 N.m (71 lb in).
3. Connect the coolant heater electrical connector (2).
4. Lower the vehicle.

ENGINE COOLANT HOT

The IPC displays ENGINE COOLANT HOT message when the IPC determines that the coolant temperature is greater than 121°C (249.8°F). The IPC receives a class 2 message from the PCM indicating the coolant temperature.

ENGINE OVERHEATED

The IPC displays ENGINE OVERHEATED message when the IPC determines that the coolant temperature is greater than 128°C (262°F). The IPC receives a class 2 message from the PCM indicating the coolant temperature.

LOW COOLANT

The IPC displays LOW COOLANT message when the IPC detects a low coolant level condition from the PCM. The IPC receives a class 2 message from the PCM indicating the coolant level.

REDUCED ENGINE POWER

The IPC displays REDUCED ENGINE POWER message when the IPC detects a reduced engine power condition from the PCM. The IPC receives a class 2 message from the PCM requesting illumination when the engine temperature reaches 132°C (270°F).

Coolant Level Control

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The powertrain control module (PCM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The instrument cluster has an internal logic which displays information on the message center. The logic receives power from the fuse block on 3 individual power circuits; ignition 3 voltage, off/run/crank voltage, and ignition 1 voltage circuit through the body wiring harness junction block. The message center receives it's power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The message center receives the signal from the logic and displays the LOW COOLANT message. The message is a continuous display shown in amber.

Coolant Heater

The optional engine coolant heater (RPO K05) operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather 29°C (20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

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

Cooling Cycle

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

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

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

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

Coolant

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

Radiator

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

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

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

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

Surge Tank

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

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

Pressure Cap

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

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

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

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

Cooling Fan and Clutch

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

Air Baffles and Seals

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

Water Pump

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

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

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

Thermostat

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

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

Thermostats (6.6L Diesel Engine)

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

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

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

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.

Scheme 236

Scheme 237

See also:
• FASTENER NOTICE
• LIFTING AND JACKING THE VEHICLE
• DIAGNOSTIC SYSTEM CHECK - ENGINE COOLING
• THERMOSTAT DIAGNOSIS
• PRESSURE CAP TESTING
• FAN REPLACEMENT
• FAN CLUTCH REPLACEMENT