Engine Cooling System: Other Pontiac Aztek I

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS in Wiring Systems.

Tools Required

J 24731 Tempil Stick

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

J 24460-01 Cooling System Pressure Tester

Scheme 68

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the J 24460-01 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.

J 24460-01 Cooling System Pressure Tester

Scheme 69

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «PRESSURE CAP TESTING»(ref-203946-S19923322132005072900000) .
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.

J 26568 Coolant and Battery Tester

Important: Do NOT add any engine coolant supplement sealant pellets to the cooling system. Drain and refill the engine cooling system every 5 years or 240 000 km, (150,000 mi), whichever occurs first.

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1. Remove and clean the coolant recovery reservoir. CAUTION: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.
2. Remove the radiator cap when the engine is cool: 2.1. Slowly rotate the cap counterclockwise to the detention tab. Do not press down while rotating pressure cap. 2.2. Wait until any residual pressure, indicated by a hissing sound, is relieved. 2.3. After all hissing stops, press down on the radiator cap and rotate the cap counterclockwise in order to remove the cap. 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.
3. Place a drain pan under the radiator drain cock in order to collect all of the used coolant.
4. Open the radiator drain cock. If only partial cooling system draining is required, drain enough coolant to perform the procedure.
5. Open the air bleed valve on the thermostat housing 2 full turns.
6. Open the air bleed valve above coolant pump 2 full turns.
7. Place a drain pan under the engine block drains in order to collect the used coolant. Important: Allow the coolant to drain completely.
8. Remove both of the engine block drains. The front left engine block drain is located between the starter motor and the engine oil filter. The rear right engine block drain is located near the crankshaft position sensor.

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1. Apply pipe sealer to the drain plug prior to installing the engine block drains. Tighten Tighten the drain plug to 19 N.m (14 lb ft).
2. Close the radiator drain cock.
3. Install the coolant recovery reservoir. 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.
4. Slowly add a 50/50 mixture of GM Goodwrench DEX-COOL® or HAVOLINE® DEX- COOL® and clean, drinkable water. Refer to Capacities-Approximate Fluid in General Information.
5. Wait for 2 minutes and reinspect the level of the coolant in the radiator. If necessary, add coolant to the radiator until the coolant level is at the base of the radiator fill neck.
6. Install the radiator cap.
7. Ensure that the radiator cap arrow points toward the radiator overflow tube. Important: The air bleed valves are brass. Do NOT over-tighten the air bleed valves.
8. Close the air bleed valve above the coolant pump.
9. Close the air bleed valve on the thermostat housing.
10. Fill the coolant reservoir with a 50/50 mixture of GM Goodwrench DEX-COOL® or HAVOLINE® DEX-COOL® and clean, drinkable water. Important: If the coolant temperature indicator turns ON, turn the engine OFF immediately and allow the engine to cool. Do NOT remove the radiator cap.
11. Start the engine and allow the engine cooling fan to cycle on and off 3 times.
12. Turn off the ignition. CAUTION: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine Is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.
13. Allow the engine to cool.
14. Top off the coolant as necessary.
15. Inspect the concentration of the engine coolant. Using the J 26568 Coolant and Battery Tester
16. Rinse away any excess coolant from the engine and engine compartment.

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.

J 38185 Hose Clamp Pliers

J 38185 Hose Clamp Pliers

J 38185 Hose Clamp Pliers

J 38185 Hose Clamp Pliers

J 38185 Hose Clamp Pliers

J 38185 Hose Clamp Pliers

J 38185 Hose Clamp Pliers

Scheme 82

1. Remove the air cleaner and duct assembly.
2. Drain the coolant until the coolant level is below the thermostat. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .
3. Remove the crossover exhaust pipe. Refer to EXHAUST CROSSOVER PIPE REPLACEMENT in Engine Exhaust.
4. Remove the radiator hose from the thermostat housing.
5. Remove the thermostat housing bolts and clean any sealer from the bolt threads.
6. Remove the thermostat housing and gasket.
7. Remove the thermostat.
8. Clean the mating surfaces.

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1. Install the thermostat.
2. Install the thermostat housing and gasket. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
3. Install the thermostat housing bolts. Tighten Tighten the bolts to 25 N.m (18 lb ft).
4. Install the radiator hose to the thermostat housing.
5. Install the crossover exhaust pipe. Refer to EXHAUST CROSSOVER PIPE REPLACEMENT in Engine Exhaust.
6. Install the air cleaner and duct assembly. Refer to in Engine Controls - 3.4L.
7. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .

Scheme 86

J 38185 Hose Clamp Pliers

Scheme 87

1. Remove the air cleaner and duct assembly. Refer to in Engine Controls-3.4L
2. Drain the coolant until the coolant level is below the thermostat. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .
3. Remove the crossover exhaust pipe. Refer to EXHAUST CROSSOVER PIPE REPLACEMENT in Engine Exhaust.
4. Remove the radiator hose from the thermostat housing.
5. Remove the thermostat housing bolts and clean any sealer from the bolt threads.
6. Remove the thermostat housing and gasket.
7. Remove the thermostat.
8. Clean the mating surfaces.

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1. Install the thermostat.
2. Install the thermostat housing and gasket.
3. Install RTV sealer (GM P/N 1052366 or the equivalent) to the thermostat housing bolt threads. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
4. Install the thermostat housing bolts. Tighten Tighten the bolts to 25 N.m (18 lb ft).
5. Install the radiator hose to the thermostat housing.
6. Install the crossover exhaust pipe. Refer to EXHAUST CROSSOVER PIPE REPLACEMENT in Engine Exhaust.
7. Install the air cleaner and duct assembly. Refer to in Engine Controls-3.4L.
8. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .

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J 38185 Hose Clamp Pliers

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1. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .
2. Remove the spark plug wire harness from the thermostat bypass pipe.
3. Remove the air inlet duct. Refer to in Engine Controls - 3.4L.
4. Remove the upper radiator hose from the thermostat housing.
5. Disconnect the left engine mount strut from the engine.
6. Remove the heater hose from the bypass pipe.
7. Remove the thermostat bypass pipe to throttle body nut.
8. Use the J 38185 in order to remove the thermostat bypass pipe hose clamps (1,5).
9. Remove the thermostat bypass pipe to cylinder head nut (3).
10. Remove the thermostat bypass pipe bolt (4).
11. Remove the thermostat bypass pipe hose.
12. Remove the thermostat bypass pipe.

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1. Apply engine coolant to the bypass pipe seal in order to ease installation.
2. Install the thermostat bypass pipe.
3. Install the thermostat bypass pipe hose.
4. Install the thermostat bypass pipe hose clamp (5). NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
5. Install the thermostat bypass pipe bolt (4). Tighten Tighten the thermostat bypass pipe bolt to 11 N.m (98 lb in).
6. Install the thermostat bypass pipe to cylinder head nut (3). Tighten Tighten the thermostat bypass pipe nut to 25 N.m (18 lb ft).
7. Install the thermostat bypass pipe to throttle body hose clamps (1).
8. Install the thermostat bypass pipe to throttle body nut. Tighten Tighten the thermostat bypass pipe nut to 25 N.m (18 lb ft).
9. Install the heater hose to the bypass pipe.
10. Install the left engine mount strut to the engine.
11. Install the upper radiator hose to the engine.
12. Install the air inlet duct. Refer to in Engine Controls - 3.4L.
13. Install the spark plug wire harness to the thermostat bypass pipe.
14. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .

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1. Drain the cooling system until the coolant is below the level of the water pump. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .
2. Remove the drive belt guard.
3. Loosen the water pump pulley bolts.
4. Remove the drive belt. Refer to DRIVE BELT REPLACEMENT in Engine Mechanical - 3.4L.
5. Remove the water pump pulley bolts.
6. Remove the water pump pulley.
7. Remove the water pump bolts.
8. Remove the water pump.
9. Remove the water pump gasket.
10. Clean the water pump mating surfaces.

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1. Install the water pump gasket.
2. Install the water pump. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
3. Install the water pump bolts. Tighten Tighten the bolts to 10 N.m (89 lb. in).
4. Install the water pump pulley.
5. Install the water pump pulley bolts.
6. Install the drive belt. Refer to DRIVE BELT REPLACEMENT in Engine Mechanical - 3.4L. Tighten Tighten the water pump pulley bolts to 25 N.m (18 lb in).
7. Install the drive belt guard.
8. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .

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1. J 38185 Hose Clamp Pliers
2. J 39400-A Halogen Leak Detector

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1. Recover the refrigerant from the A/C system. Refer to REFRIGERANT RECOVERY AND RECHARGING in Heating, Ventilation and Air Conditioning.
2. Drain the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .
3. Remove the cooling fans with the cooling fan shroud. Refer to «COOLING FAN REPLACEMENT - ELECTRIC»(ref-203946-S16456024852005072900000) .
4. Reposition the hose clamp at the water pump housing using the J 38185.
5. Disconnect the radiator outlet hose from the water pump housing.
6. Raise the vehicle. Refer to LIFTING AND JACKING THE VEHICLE in General Information.
7. Reposition the hose clamp at the radiator using the J 38185.
8. Disconnect the radiator outlet hose from the radiator.
9. Remove the radiator outlet hose.
10. Disconnect the lower TOC line from the radiator. Refer to TRANSMISSION OIL COOLER LINE QUICK CONNECT FITTING in Automatic Transaxle - 4T65-E.
11. Lower the vehicle.
12. Remove the nut which secures the A/C discharge hose to the condenser block.
13. Disconnect the A/C discharge hose from the condenser block.
14. Remove and discard the sealing washer. Important: Cap or tape off the open A/C hose immediately to prevent system contamination.
15. Cap or tape off the A/C discharge hose.
16. Remove the bolt which secures the evaporator inlet tube to the condenser block.
17. Disconnect the evaporator inlet tube from the condenser block.
18. Cap or tape off the evaporator inlet tube.
19. Remove the radiator and condenser assembly.
20. Remove the condenser tube clip bolt.
21. Remove the condenser mounting bolts.
22. Remove the condenser from the radiator.

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1. Install the condenser to the radiator. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) in Cautions and Notices.
2. Install the mounting bolts that secure the condenser to the radiator. Tighten Tighten the bolts to 6 N.m (53 lb. in).
3. Install the condenser tube clip bolt. Tighten Tighten the bolt to 2.5 N.m (22 lb. in).
4. Install the radiator and condenser assembly.
5. Remove the cap or the tape from the evaporator inlet tube.
6. Install a new seal washer to the evaporator inlet tube. Refer to SEALING WASHER REPLACEMENT .
7. Install the evaporator inlet tube and the bolt to the condenser block. Tighten Tighten bolt to 16 N.m (12 lb ft).
8. Remove the cap or the tape from the A/C discharge hose.
9. Install a new sealing washer to the A/C discharge hose. Refer to SEALING WASHER REPLACEMENT .
10. Install the A/C discharge hose and the nut to the condenser block. Tighten Tighten the nut to 16 N.m (12 lb ft).
11. Raise the vehicle.
12. Connect the lower TOC line to the radiator. Refer to TRANSMISSION OIL COOLER LINE QUICK CONNECT FITTING in Automatic Transaxle - 4T65-E.
13. Install the radiator outlet hose.
14. Connect the radiator outlet hose to the radiator.
15. Reposition the hose clamp at the radiator to secure the hose using the J 38185.
16. Lower the vehicle.
17. Connect the radiator outlet hose to the water pump housing.
18. Reposition the hose clamp at the water pump housing to secure the hose using the J 38185.
19. Install the cooling fans with the cooling fan shroud. Refer to «COOLING FAN REPLACEMENT - ELECTRIC»(ref-203946-S16456024852005072900000) .
20. Fill the cooling system. Refer to «DRAINING AND FILLING COOLING SYSTEM»(ref-203946-S00496132822005072900000) .
21. Evacuate and recharge the A/C system. Refer to REFRIGERANT RECOVERY AND RECHARGING in Heating, Ventilation and Air Conditioning.
22. Leak test the fittings of the component using the J 39400-A.
23. Inspect the transmission fluid level. Refer to TRANSMISSION FLUID CHECKING PROCEDURE in Automatic Transaxle - 4T65-E.

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Cooling Fan Control

The engine cooling fan system is controlled by the Body control module (BCM) and the Powertrain control module (PCM). The BCM performs the calculations as to how long, when and what speed the cooling fans should turn on. The BCM then sends a class 2 message to the PCM to engage the cooling fan relays.

If there is a malfunction with the BCM, the PCM will control the engine cooling fans independently.

The engine cooling system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the PCM to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood accessory wiring junction block. The ground path is provided at G100.

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 left cooling fan. The ground path for the left cooling fan is through the cooling fan 2 relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the 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 3 relay and the cooling fan 2 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left 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 right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The BCM and PCM command Low Speed Fans on under the following conditions

1. Engine coolant temperature exceeds approximately 106°C (223°F).
2. A/C refrigerant pressure exceeds 1310 kPa (190 psi).
3. After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The BCM and PCM command High Speed Fans on under the following conditions

1. Engine coolant temperature reaches 110°C (230°F).
2. A/C refrigerant pressure exceeds 1655 kPa (240 psi).
3. When certain DTCs set.

Hot Coolant Temp

The IPC illuminates the hot coolant temp indicator in the message center when the PCM determines that the coolant temperature is greater than 128°C (262°F). 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 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 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. 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 jackets surrounding the cylinders, where the radiator 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 the radiator absorbs additional heat.

Coolant is also directed to the throttle body, where 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 radiator 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.

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 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.

Radiator

The radiator is a heat exchanger. It 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 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 hand tank. The drain cock includes the drain cock and drain cock seal.

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

During vehicle use, the coolant 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 is a cap that seals and pressurizes the cooling system. It 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 if it exceeds 15 psi. The vacuum valve is held against the seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as the radiator 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 is, the faster the heat moves from the radiator to the cooler, passing air. The pressure in the cooling system can get too high, however. When the pressure exceeds the strength of the spring, the pressure valve rises 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 reservoir is partially filled with coolant and is connected to the radiator fill neck with the overflow tube. Coolant can flow back and forth between the radiator and the reservoir.

In effect, a cooling system with a coolant recovery reservoir is a closed system. When the pressure in the cooling system gets too high, the pressure valve opens in the pressure cap. This allows the coolant, which has expanded due to being heated, is allowed to flow through the overflow tube and into the recovery reservoir. As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum opens the vacuum valve in the pressure cap, allowing some of the coolant in the reservoir to be siphoned back into the radiator.

Under normal operating conditions, coolant is not lost. Although the coolant level in the recovery reservoir goes up and down, the radiator and cooling system are kept full. An advantage to using a coolant recovery reservoir is that most of the air bubbles are eliminated 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 to increase system cooling. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle to flow through the radiator and increase cooling. Air baffles are also used to direct airflow into the radiator and increase cooling. Air seals prevent air from bypassing the radiator and A/C condenser. Air seals also prevent recirculation of the air for better hot weather cooling and A/C condenser performance.

The transmission oil pump, pumps the fluid through the transmission oil cooler feed line to the oil cooler. The fluid then flows down 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.

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. With a sealed bearing, grease cannot leak out, and dirt and water cannot get in.

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 regulate the operating temperature of the engine. It 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 diaphragm. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

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 that surrounds the oil cooler as the transmission fluid passes down through the cooler.

Scheme 112