Engine Cooling System Buick LeSabre VIII

Fastener Tightening Specifications

Fastener Tightening Specifications

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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 modules which command the system.
2. The ability of the control modules to communicate through the class 2 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 number(s) below refer to the step number(s) 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 Instrument Cluster or Powertrain Control Modules have 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.

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Scan Tool Data Definitions

Commanded Fan 1/Commanded Fan 2: This represents the PCM commanded state of the fan 1, or low speed, and fan 2, or high speed control circuits.

ECT: The scan tool displays -40°C to +151°C (-40°F to +304°F). The Engine Coolant Temperature (ECT) sensor is mounted in the coolant stream. The PCM applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high signal voltage and interprets it 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.

FC Relay 1: The scan tool displays OK or Fault. This parameter indicates the state of the driver circuit for this device.

FC Relay 2 and 3: The scan tool displays OK or Fault. This parameter indicates the state of the driver circuit for this device.

Fans High Speed: The scan tool displays On or Off. The PCM is commanding all three fan control relays on when the scan tool indicates On. When all fan control relays are activated, both cooling fans are enabled on high speed.

Fans Low Speed: The scan tool displays On or Off. The PCM is commanding Fan Control relay 1 On when the scan tool indicates On. When the PCM commands the Fan Control relay 1 On, both fans are enabled on low speed.

Hot Temp. Lamp: The instrument panel cluster (IPC) illuminates the temperature indicator whenever the PCM sends a class 2 message requesting illumination. The class 2 message for the indicator is the same as that for the temperature gauge. The IPC determines when illumination of the indicator occurs based on the temperature value the IPC receives. The IPC will turn on the indicator when the engine temperature reaches 124°C (255°F) and turn off at 119°C (246°F).

Scheme 19

Circuit Description

Battery positive voltage is supplied to the cooling fan 1 relay from the cool fan 1 fuse. The powertrain control module (PCM) controls the cooling fan 1 relay by grounding the low speed cooling fan relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage potential of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM will monitor the control circuit for the following

1. A short to ground.
2. A short to voltage.
3. An open circuit.
4. An open relay coil.
5. An internally shorted or excessively low resistance relay coil.

When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

Conditions for Running the DTC

1. The ignition is ON.
2. The system voltage is between 9-18 volts.

Conditions for Setting the DTC

1. An improper voltage level has been detected on the low speed cooling fan relay control circuit.
2. The above conditions are present for at least 30 seconds.

Action Taken When the DTC Sets

1. The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
2. The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
3. A history DTC is stored.

Conditions for Clearing the MIL/DTC

1. The PCM will turn OFF the MIL during the third consecutive trip in which 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.

Diagnostic Aids

Inspect for the following conditions

1. If the condition is not present, refer to «TESTING FOR INTERMITTENT AND POOR CONNECTIONS»(/buick/lesabre/viii-2000-2005/remont/body-electrical/#testing-wiring-systems-for-intermittent-poor-connections) .
2. Review the Freeze/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

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

1. 2) - Listen for an audible click when the cooling fan 1 relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
2. 3) - Tests for voltage at the coil side of the cooling fan 1 relay. The cool fan 1 fuse supplies battery positive voltage to the coil side of the cooling fan 1 relay.
3. 4) - Verifies that the PCM is providing ground to the cooling fan 1 relay.
4. 5) - Tests if ground is constantly being applied to the cooling fan 1 relay.

Battery positive voltage is supplied to the cooling fan s/p relay and the cooling fan 2 relay from the cool fan 2 fuse. The powertrain control module (PCM) controls the relays by grounding the high speed cooling fan relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage potential of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM will monitor the control circuit for the following

1. A short to ground.
2. A short to voltage.
3. An open circuit.

When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

1. The ignition is ON.
2. The system voltage is between 9 and 18 volts.

1. An improper voltage level has been detected on the low speed cooling fan relay control circuit.
2. The above conditions are present for at least 30 seconds.

1. The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
2. The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
3. A history DTC is stored.

1. The PCM will turn OFF the MIL during the third consecutive trip in which 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.

Check for the following conditions

1. If the condition is not present, refer to «TESTING FOR INTERMITTENT AND POOR CONNECTIONS»(/buick/lesabre/viii-2000-2005/remont/body-electrical/#testing-wiring-systems-for-intermittent-poor-connections) .
2. Review the Freeze/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

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

1. 2) - Listen for an audible click when the cooling fan s/p and the cooling fan 2 relays operate. Command both the ON and OFF states. Repeat the commands as necessary.
2. 3) - Tests for voltage at the coil side of the cooling fan 2 relay. The cool fan 2 fuse supplies battery positive voltage to the coil side of the cooling fan 2 relay.
3. 4) - Verifies that the PCM is providing ground to the cooling fan 2 relay.
4. 5) - Tests if ground is constantly being applied to the cooling fan 2 relay.

Symptoms - Engine Cooling

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to Cooling System Description & Operation .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Cooling System.
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 .

Symptom List

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

1. Engine Coolant Temperature Indicator Always On. (Scheme 24)
2. Cooling Fan Always On. (Scheme 25)
3. See «Cooling Fan Inoperative»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system).
4. See «Engine Overheating»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system).
5. See «Loss of Coolant»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system).
6. See «Thermostat Diagnosis»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__thermostat-diagnosis).
7. See «Coolant Heater Inoperative»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system).
8. See «Engine Fails To Reach Normal Operating Temperature»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system).

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Thermostat Diagnosis

Tools Required: J 24731 Tempilstick

Thermostat Test

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 tempilstick in order to find the opening and the closing temperatures of the coolant thermostat. J 24731-188 tempilstick melts at 87°C (188°F). The thermostat should begin to open. J 24731-206 tempilstick 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. Refer to «Thermostat Replacement»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__thermostat-replacement) .

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Draining & Filling Cooling System

Draining Procedure

Important: Recover and store used coolant in a used coolant holding tank and submit the used coolant for recycling on a regular basis. Do NOT pour used coolant down the drain. Ethylene glycol antifreeze is very toxic. Disposing of Ethylene glycol into the sewer system or ground water is both illegal and ecologically unsound.

Scheme 30

1. Place a drain pan under the radiator drain valve in order to collect all of the used coolant.
2. Remove the radiator pressure cap. 2.1. Clean the cap. 2.2. Test the cap. 2.3. If necessary, replace the cap. 2.4. Clean the radiator filler neck. Inspect the filler neck.
3. Completely drain the cooling system by opening the radiator drain cock at the bottom of the radiator.
4. If the coolant is dirty, or if there are deposits in the radiator, flush the cooling system before refilling. Refer to «Flushing»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__flushing) .
5. Disconnect the hose from the coolant recovery reservoir. Remove the reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__coolant-recovery-reservoir-replacement) . 5.1. Clean the outside of the coolant recovery reservoir. 5.2. Pour out any fluid. 5.3. Thoroughly clean the inside of the reservoir using soap and water. 5.4. Thoroughly flush the reservoir with clean water. Drain the reservoir. Install the reservoir. Connect the reservoir hose. Refer to «Coolant Recovery Reservoir Replacement»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__coolant-recovery-reservoir-replacement) .

Filling Procedure

Note. Do not add cold water to the cooling system with the engine at or above operating temperature. Adding cold water causes rapid cooling, resulting in possible engine damage.

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.

Note. When adding coolant, it is important that you use GM Goodwrench DEX-COOL® or HAVOLINE® DEX-COOL® coolant. If Coolant other than DEX-COOL® or HAVOLINE® DEX-COOL® is added to the system the engine coolant will require change sooner; at 50 000 km (30,000 mi) or 24 months.

Note. Do not use a solution stronger than 70 percent antifreeze. Pure antifreeze can freeze at -22°C (-8°F).

1. Fill the radiator and the coolant reservoir to the full cold line with GM Goodwrench® DEX-COOL® or Havoline® DEX-COOL®. To ensure sufficient engine cooling, freezing and corrosion protection, maintain the protection level at -37°C (-34°F) lower.
2. Wait for two minutes and recheck the level of the coolant in the radiator. If necessary, add coolant to radiator until the coolant level is at the base of the radiator fill neck.
3. Install the radiator pressure cap, making sure the arrows on the cap line up with the coolant recovery tube.
4. Place the heater and A/C control in any A/C mode except Max and the temperature in the highest setting.
5. Start the engine and allow to idle until the lower radiator to coolant pump hose is hot.
6. Cycle the engine speed up to about 3000 RPM and back to idle five times. Slowly open the bleed valve on the top of the thermostat housing for approximately 15 seconds to expel any trapped air in the cooling system.
7. Close the air bleed valve. Do not overtighten.
8. Allow the engine to cool to outside temperature. Ensure the coolant level in the reservoir and the radiator are at the proper levels.

Flushing

Important: Do NOT add any engine coolant supplement sealant pellets to the cooling system.

1. Park the vehicle on a level surface.
2. Remove and clean (flush) the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__coolant-recovery-reservoir-replacement) .
3. Flush the engine cooling system. Follow the flushing equipment manufacturer's instructions.
4. Install the coolant recovery reservoir. Refer to «Coolant Recovery Reservoir Replacement»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__coolant-recovery-reservoir-replacement) .
5. Fill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-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.

Coolant Recovery Reservoir Replacement

Tools Required: J 38185 Hose Clamp Pliers

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1. Drain the coolant. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
2. Disconnect the coolant hose from the recovery reservoir using the J 38185 .
3. Remove the coolant recovery reservoir nuts and bolt.
4. Remove the recovery reservoir from the vehicle.

Installation Procedure

1. Install the coolant reservoir.
2. Install the mounting nuts and bolt. Tighten the fasteners to 6 N.m (53 in lbs).
3. Install the coolant hose to the reservoir using the J 38185 .
4. Refill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .

Radiator Hose Replacement - Inlet

Tools Required: J 38185 Hose Clamp Pliers

Scheme 33

1. Drain the engine coolant. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
2. Using the J 38185 loosen and move the inlet radiator hose clamp at the radiator.
3. Remove the inlet radiator hose from the radiator.
4. Using the J 38185 loosen and move the inlet radiator hose clamp at the engine.
5. Remove the inlet radiator hose from the engine.

1. Install the inlet radiator hose to the engine.
2. Install the inlet radiator hose to the radiator.
3. Using the J 38185 install the inlet radiator hose clamps.
4. Fill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .

Radiator Hose Replacement - Outlet

Tools Required: J 38185 Hose Clamp Pliers

Removal Procedure

1. Drain the engine coolant. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system).
2. Using the J 38185 loosen and move the outlet radiator hose clamp at the radiator.
3. Remove the outlet radiator hose from the radiator. (Scheme 40)
4. Using the J 38185 loosen and move the outlet radiator hose clamp at the engine.
5. Remove the outlet radiator hose from the engine.

1. Install the outlet radiator hose to the engine.
2. Install the outlet radiator hose to the radiator.
3. Using the J 38185 install the outlet radiator hose clamps.
4. Fill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .

Cooling Fan Replacement - Electric

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1. Disconnect the battery negative cable.
2. Remove the upper radiator support bar.
3. Disconnect the wiring harness electrical connector from the motor and the fan bracket.
4. Remove the transaxle oil cooler pipe bracket bolt from the fan shroud.
5. Remove the two fan mounting bolts.
6. Lift the fan assembly off the lower holding tabs and remove from the vehicle.

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1. Install the fan assembly and insert into the lower radiator holding tabs.
2. Install the electric cooling fan mounting bolts Tighten the bolts to 9 N.m (80 in lbs).
3. Align the transaxle oil cooler pipes with the routing features (1, 2) on the fan shroud.
4. Install the transaxle oil cooler pipe bracket bolt to the fan shroud. Tighten the bolt to 10 N.m (89 in lbs).
5. Connect the wiring harness electrical connectors to the fan motors.
6. Install the upper radiator support bar.
7. Connect the battery negative cable.

Scheme 38

1. Remove the electric cooling fan. Refer to «Cooling Fan Replacement - Electric»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__cooling-fan-replacement-electric) . Important: The fan blade retaining nut is left hand thread.
2. Remove the fan blade retaining nut (5) from the electric cooling fan motors (2).
3. Remove the fan blade (4) from the motor shaft.
4. Remove the cooling fan motor retaining screws (3).
5. Remove the cooling fan motor (2) from the shroud (1).

1. Install the cooling fan motor (2) to the shroud (1).
2. Install the cooling fan motor retaining bolts (3). Tighten the bolts to 6 N.m (53 in lbs).
3. Install the cooling fan blade (4) to the motor shaft. Important: The fan blade retaining nut is left hand thread.
4. Install the cooling fan retaining nut (5) to the motors (2). Tighten the nut to 6 N.m (53 in lbs).
5. Install the electric cooling fan. Refer to «Cooling Fan Replacement - Electric»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__cooling-fan-replacement-electric) .

Thermostat Replacement

Tools Required: J 38185 Hose Clamp Pliers

Scheme 39

1. Remove the engine cover. Refer to «FUEL INJECTOR SIGHT SHIELD REPLACEMENT»(/buick/lesabre/viii-2000-2005/remont/mechanical/#engine-mechanical-38l-on-vehicle) .
2. Drain the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
3. Using the J 38185 loosen and move the inlet radiator hose clamp at the thermostat housing.
4. Remove the inlet hose from the housing.
5. Remove the thermostat housing bolts (1).
6. Remove the thermostat housing (2).
7. Remove the thermostat (4).
8. Clean the gasket mating surfaces and the housing and intake port.

1. Install the thermostat (4).
2. Install the thermostat housing (2) and a new gasket (3).
3. Install the thermostat housing bolts (1). Tighten the thermostat housing bolts to 20 N.m (15 ft lbs).
4. Install the inlet radiator hose and clamp.
5. Refill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
6. Install the engine cover. Refer to «FUEL INJECTOR SIGHT SHIELD REPLACEMENT»(/buick/lesabre/viii-2000-2005/remont/mechanical/#engine-mechanical-38l-on-vehicle) .

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Scheme 42

1. Drain the engine coolant. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
2. Remove the drive belt. Refer to «DRIVE BELT REPLACEMENT»(/buick/lesabre/viii-2000-2005/remont/mechanical/#engine-mechanical-38l-on-vehicle) .
3. Remove the water pump pulley bolts.
4. Remove the water pump pulley.
5. Remove the water pump mounting bolts (1, 2).
6. Remove the water pump.
7. Clean the gasket mating surfaces.
8. Clean and inspect the water pump. Refer to «WATER PUMP CLEANING & INSPECTION»(/buick/lesabre/viii-2000-2005/remont/mechanical/#engine-mechanical-38l-unit-repair) .

Scheme 43

1. Using a new gasket, install the water pump on the engine.
2. Install the water pump mounting bolts (1, 2). Tighten the short bolts (1) to 15 N.m (11 ft lbs). Tighten the long bolts (2) to 30 N.m (22 ft lbs).
3. Install the water pump pulley and bolts. Tighten the water pump pulley bolts to 13 N.m (115 in lbs).
4. Install the drive belt. Refer to «DRIVE BELT REPLACEMENT»(/buick/lesabre/viii-2000-2005/remont/mechanical/#engine-mechanical-38l-on-vehicle) .
5. Fill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .

Radiator Replacement

Tools Required

1. J 38185 Hose Clamp Pliers
2. J 41623-B Cooler Quick Connect Tool

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Scheme 47

1. Drain the engine coolant. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
2. Remove the upper radiator seal.
3. Remove the upper tie bar.
4. Using the J 38185 , disconnect the coolant overflow hose from the radiator.
5. Plug the coolant overflow hose.
6. Disconnect the upper and lower radiator hoses from the radiator using the J 38185 , and position the hoses aside.
7. Remove the transaxle oil cooler pipe bracket bolt from the lower tie bar.
8. Remove the cooling fans. Refer to «Cooling Fan Replacement - Electric»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__cooling-fan-replacement-electric) .
9. Slide the plastic cap off the transaxle oil cooler pipe quick connect fittings.
10. Disconnect the upper (1) and lower (2) transaxle oil cooler pipes from the radiator using the J 41623-B .
11. Remove the A/C condenser mounting bolts.
12. Separate the condenser from the radiator.
13. Lift the radiator up and out of the vehicle.

Note. The bolt retaining the condenser to the radiator end tank is a special length and should be the ONLY bolt used upon reinstallation. The use of a longer bolt will damage the radiator end tank.

Scheme 48

1. Install the radiator to the vehicle. Place the bottom of the radiator in the lower pads.
2. Install the condenser to the radiator.
3. Install the A/C condenser mounting bolts. Tighten the bolts to 13 N.m (115 in lbs).
4. Push the upper and lower transaxle oil cooler pipes into the radiator quick connect fittings, until a "click" is heard.
5. Tug gently on the cooler pipes to ensure proper retention.
6. Slide the plastic caps (1) over the quick connect joints.
7. Install the cooling fans. Refer to «Cooling Fan Replacement - Electric»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__cooling-fan-replacement-electric) .
8. Install the transaxle oil cooler pipe bracket bolt to the lower tie bar. Tighten the bolt to 10 N.m (89 in lbs).
9. Install the upper and lower radiator hoses to the radiator using the J 38185 .
10. Connect the coolant recovery hose to the radiator neck using the J 38185 .
11. Install the upper tie bar.
12. Install the upper radiator seal.
13. Fill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
14. Inspect the transmission oil level.

Scheme 49

1. Drain the engine coolant. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
2. Raise and support the vehicle.
3. Remove the lower radiator air deflector.
4. Disconnect the coolant heater cord (2) from the coolant heater (1).
5. Loosen the bolt at the coolant heater, but do not remove.
6. Remove the coolant heater.
7. Remove and clean any burrs, compound, paint, or rough spots from the core plug hole.

Scheme 50

1. Apply a coat of Permatex® Thread Sealant with Teflon to the O-ring. Important: Ensure both locking wings (1) are positioned against the inner wall of the engine block.
2. Install the coolant heater by pushing tight to the block.
3. Install the coolant heater so the element (1) is positioned at approximately the 3 o'clock position.
4. Tighten the bolt until both locking wings draw tight against the inner wall of the engine block. Tighten the coolant heater bolt to 2 N.m (18 in lbs).
5. Install the coolant heater cord (2) to the coolant heater.
6. Fill the cooling system. Refer to «Draining & Filling Cooling System»(/buick/lesabre/viii-2000-2005/remont/cooling-fan/#engine-cooling-system__draining-filling-cooling-system) .
7. Install the lower radiator air deflector.

Scheme 51

1. Disconnect the coolant heater cord (2) from the coolant heater (1).
2. Cut the coolant heater cord straps (3) from the positive battery cable conduit.
3. Remove the coolant heater cord (2) from the vehicle.

1. Install the coolant heater cord (2) to the vehicle.
2. Connect the coolant heater cord (2) to the coolant heater (1). see scheme 49
3. Route the coolant heater cord (2) along the positive battery cable conduit. Important: Ensure all slack is removed from the coolant heater cord (2) prior to tightening the coolant heater cord straps (3).
4. Tie new coolant heater cord straps (3) to the positive battery cable conduit.
5. Secure the excess coolant heater cord (2) to the underhood fuse block harness, behind the tie bar.

Cooling Fan Control

The engine cooling fan system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G103.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the right cooling fan. The ground path for the right cooling fan is through the cooling fan s/p relay and the left cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

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

1. The engine coolant temperature exceeds approximately 106°C (223°F).
2. The A/C refrigerant pressure exceeds 1310 kpa (190 psi).
3. After the vehicle is shut OFF, the engine coolant temperature is greater than 118°C (244°F) and the system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

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

1. The engine coolant temperature reaches 112°C (234°F).
2. The A/C refrigerant pressure exceeds 1634 kpa (237 psi).

CHECK GAGES TEMPERATURE - 44 (with DIC)

The IPC illuminates the CHECK GAGES TEMPERATURE - 44 indicator in the DIC when the IPC determines that the coolant temperature is greater than 124°C (255°F). The IPC receives a class 2 message from the PCM indicating the coolant temperature. The IPC sends a class 2 message to the radio in order to activate an audible warning.

ENGINE HOT A/C DISABLED - 16 (with DIC)

The IPC illuminates the ENGINE HOT A/C DISABLED - 16 indicator in the DIC when the PCM determines that the coolant temperature is above the normal operating range. The PCM disables the air conditioning compressor. The IPC receives a class 2 message from the PCM requesting illumination. The IPC sends a class 2 message to the radio in order to activate an audible warning.

Coolant Heater

The optional engine coolant heater (RPO K05) is rated at 400 watts and supplies 1365 btu/hr. The engine coolant heater operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather -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 maintains an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system removes approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the system cools slowly or not at all. 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. Some coolant will then be pumped from the water pump to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.

Coolant is also pumped 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 the coolant absorbs heat.

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

Coolant is also directed to the throttle body. There the coolant 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 keeping the throttle body cool.

From the cylinder heads, the coolant is then forced to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine is warmed, or the coolant will flow through the thermostat and into the radiator where the coolant is cooled and the coolant cycle is completed.

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 clean drinkable 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. The radiator consists of a core and two tanks. The aluminum core is a crossflow tube and fin design. This is a series of tubes that extend side to side from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes in order to improve heat transfer from the coolant to the atmosphere. The inlet and outlet tanks are molded with a high-temperature, nylon-reinforced plastic. A high-temperature rubber gasket seals the tank flange edge. 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 which is located in the bottom of the left tank. The drain cock includes the drain cock and drain cock seal.

The radiator removes heat from the coolant passing through the radiator. The fins on the core absorb heat from the coolant passing through the tubes. Air which passes between the fins absorbs heat and cools the coolant.

During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Pressure Cap

The pressure cap seals and pressurizes the cooling system. The cap contains a blow-off or pressure valve and a vacuum or atmospheric valve. The pressure valve is held against the seat by a spring of predetermined strength, which protects the radiator by relieving pressure exceeds 15 psi. The vacuum valve is held against the seat by a spring, which permits opening of the valve in order to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator to collapse.

The pressure cap allows pressure in the cooling system to build up. As the pressure builds, the boiling point of the coolant goes up as well. Therefore, the coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant, the faster the heat moves from the radiator to the cooler surrounding air. The pressure in the cooling system can get too high, however. When the pressure exceeds the strength of the spring, the pressure raises the pressure valve so that the excess pressure can escape. 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 cooling system. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator from collapsing.

Coolant Recovery System

The coolant recovery system consists of a plastic coolant recovery reservoir and overflow tube. The recovery reservoir is also called a recovery tank or expansion tank. This tank 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. High pressure in the cooling system 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, 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 fluctuates, the radiator and the cooling system are kept full. A coolant recovery reservoir eliminates almost all air bubbles from the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Air Baffles and Seals

The cooling system uses deflectors, air baffles and air seals in order to increase system cooling. Deflectors are installed under the vehicle which redirect the airflow beneath the vehicle through the radiator and increase cooling. Air baffles also direct the airflow into the radiator and increase cooling. Air seals prevent air from bypassing the radiator and the A/C condenser. Air seals also prevent recirculation of the 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 a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by one or more sealed bearings. These sealed bearings never need to be lubricated. In a sealed bearing, grease cannot leak out, and dirt and water cannot get in.

The water pump circulates 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. The thermostat regulates the operating temperature of the engine. The thermostat utilizes a temperature-sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, the element expands and exerts pressure against a rubber diaphragm. This pressure forces the valve to open. As the element is cooled, the element contracts. This contraction allows a spring to push the valve closed.

When the coolant temperature is below 91°C (195°F), the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 91°C (195°F), 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, even after the valve has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

Transmission Oil Cooler

The transmission oil cooler is a heat exchanger. The cooler is located inside the right end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the transmission fluid passes through the cooler.

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

Scheme 52

See also:
• TESTING FOR INTERMITTENT AND POOR CONNECTIONS
• FUEL INJECTOR SIGHT SHIELD REPLACEMENT
• WATER PUMP CLEANING & INSPECTION
• Diagnostic System Check - Engine Cooling
• Thermostat Diagnosis
• Thermostat Replacement
• Flushing
• Coolant Recovery Reservoir Replacement
• Draining & Filling Cooling System
• Cooling Fan Replacement - Electric