Engine Cooling System: Other Oldsmobile Bravada III

Intermittent

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

Engine Coolant Temperature Indicator Always On

Engine Coolant Temperature Indicator Always On

Engine Overheating

Engine Overheating

Loss of Coolant

Loss of Coolant

Coolant Heater Inoperative

Coolant Heater Inoperative

Engine Fails To Reach Normal Operating Temperature

Engine Fails To Reach Normal Operating Temperature

Tools Required

J 24460-01 Cooling System Pressure Tester. See Special Tools and Equipment .

J 24460-01 Cooling System Pressure Tester. See Special Tools and Equipment .

Filling Procedure

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.

Scheme 52

1. Ensure that the radiator drain cock is closed.
2. Ensure that the heater hoses are secure to the fittings.
3. Add the DEX-COOL® to the radiator, then add clean drinkable water to the cooling system. If you use the old coolant, ensure that the solution is clean and clear, and that the solution is a 50/50 mixture of DEX-COOL® and water.
4. Place a large top funnel in the radiator filler neck or surge tank.
5. Slowly pour in the coolant. Because the thermostat is closed, filling the cooling system may be slow.
6. After you fill the cooling system, start the engine and let the cooling system warm up. When the thermostat opens, the coolant level may drop. If the level drops, add coolant as needed.
7. Install the radiator cap.
8. Inspect the coolant level in the recovery reservoir tank. Add coolant as needed.

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.

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.

Scheme 53

1. Remove the air cleaner assembly.
2. Remove the bracket bolt securing the accumulator to the coolant recovery reservoir (1).
3. Move the accumulator out of the way.
4. Remove the coolant hoses from the coolant recovery reservoir and plug the hoses and the coolant recovery reservoir outlets with suitable plugs (2).
5. Remove the nut and bolt securing the coolant recovery reservoir.
6. Remove the coolant recovery reservoir.

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

Scheme 54

Scheme 55

1. Drain the coolant. Refer to «Draining and Filling Cooling System»(ref-191875-S40604209312005091600000) .
2. Reposition the inlet radiator hose clamp at the thermostat (1) using J 38185 .
3. Remove the inlet radiator hose from the thermostat.
4. Raise the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(ref-189249) in General Information.
5. Remove the lower radiator support shield, if equipped. Refer to «RADIATOR SUPPORT SHIELD REPLACEMENT»(ref-191509-S01572464802005091600000) in Frame and Underbody.
6. Reposition the inlet radiator hose clamp at the radiator using J 38185 .
7. Remove the inlet radiator hose (1) from the radiator.

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

Scheme 56

1. Drain the engine coolant. Refer to «Draining and Filling Cooling System»(ref-191875-S40604209312005091600000) .
2. Reposition the inlet radiator hose clamp (2) at the radiator using J 38185 .
3. Remove the inlet radiator hose from the radiator.
4. Reposition the inlet radiator hose clamp (1) at the engine outlet using J 38185 .
5. Remove the inlet radiator hose from the engine.

1. J 41240 Fan Clutch Remover and Installer. See «Special Tools and Equipment»(ref-191875-S09847128532005091600000) .
2. J 38185 Hose Clamp Pliers. See «Special Tools and Equipment»(ref-191875-S09847128532005091600000) .
3. J 46406 Fan Clutch Remover and Installer. See «Special Tools and Equipment»(ref-191875-S09847128532005091600000) .

Scheme 57

Scheme 58

Scheme 59

1. Remove the hood latch support. Refer to «HOOD LATCH SUPPORT REPLACEMENT»(ref-190171-S14953242532005091300000) in Body Front End.
2. Disconnect the transmission cooler lines at the engine and release the lines from the fan shroud.
3. Remove the 2 upper bolts on the fan shroud.
4. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-191875-S40604209312005091600000) .
5. Reposition the upper inlet radiator hose clamp using J 38185 .
6. Remove the upper inlet radiator hose from the radiator.
7. Remove the electrical connector from the shroud.
8. Position the water pump so the bolts are aligned in the vertical.
9. Remove the fan hub nut from the water pump shaft in a counterclockwise rotation. Using the J 46406 , in order to secure the water pump pulley, loosen the cooling fan hub nut from the water pump shaft.
10. Unclip the fan shroud from the radiator at the side panels (1).
11. Tilt the radiator and the condenser forward.
12. Lift the fan and the shroud up and out towards the engine to release the fan from the radiator to clear the radiator inlet.

J 43244 Relay Puller Pliers. See Special Tools and Equipment .

Scheme 60

1. Remove the underhood electrical center cover.
2. Using the J 43244 , remove the cooling fan relay (3).

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

Scheme 61

1. Remove the necessary coolant from the radiator. Refer to «Draining and Filling Cooling System»(ref-191875-S40604209312005091600000) .
2. Remove the generator. Refer to «GENERATOR»(ref-167407-S09419884042004101300000) .
3. Loosen the outlet hose clamp at the thermostat housing (1). Remove the outlet hose from the thermostat housing.
4. Remove the thermostat housing bolts.
5. Remove the thermostat housing from the engine block.
6. Clean all of the surfaces of the thermostat housing.
7. Clean the sealing surface of the engine block.

Tool Required

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

Scheme 62

Scheme 63

1. Drain the coolant. Refer to «Draining and Filling Cooling System»(ref-191875-S40604209312005091600000) .
2. Remove the fan and shroud. Refer to «Cooling Fan and Shroud Replacement»(ref-191875-S38442111002005091600000) .
3. Remove the drive belt. Refer to «DRIVE BELT REPLACEMENT»(ref-158534-S30389669122005081800000) .
4. Using the J 41240 , secure the water pump pulley and remove the water pump pulley bolts.
5. Remove the J 41240 .
6. Remove the water pump pulley.
7. Loosen and remove the water pump bolts.
8. Remove the water pump.
9. Clean and inspect the water pump. Refer to «WATER PUMP CLEANING AND INSPECTION»(ref-184762-S01094086412005082400000) .
10. Discard and replace the gasket.

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

Cooling Fan Control

The purpose of the electro-viscous (EV) fan clutch is to maintain powertrain cooling requirements. The powertrain control module (PCM) monitors the following sensors to regulate the fan speed

1. Engine coolant temperature sensor
2. A/C refrigerant pressure sensor
3. Vehicle speed sensor
4. Intake air temperature sensor
5. Transmission fluid temperature sensor
6. Ambient air temperature sensor

The PCM controls the electro-viscous fan clutch engagement. The PCM regulates a 12-volt pulse width modulated signal (PWM) to the cooling fan relay. The PWM signal determines the ON time of the relay. As the commanded state of the fan clutch increases, so does the ON time of the relay. This ON time directly effects the amount of time the solenoid, which is internal to the fan clutch, is energized. When the solenoid in the fan clutch is energized, it opens the spring loaded valve and allows fluid to flow from the storage chamber to the fluid coupling of the cooling fan clutch, increasing the fan speed. When the solenoid is de-energized, the spring loaded valve closes, and blocks the path of the fluid to the fluid coupling of the fan clutch, reducing fan speed.

The fan has the ability to create a feedback signal, so the PCM has an actual fan speed input. This is done with a hall effect sensor internal to the fan clutch. The PCM supplies a 5-volt reference and a low reference to the hall effect sensor. The hall effect sensor returns a signal pulse through the cooling fan speed signal circuit in response to the reluctor track passing by the magnetic field of the hall effect sensor.

The PCM commands the cooling fan to 100% under the following conditions

1. Engine coolant temperature exceeds approximately 129°C (264°F).
2. The transmission oil temperature exceeds approximately 151°C (304°F).
3. A/C refrigerant pressure exceeds 1655 kPa (240 psi).
4. When certain DTC's set. These include P0116, P0117, P0118, P0125, P1481, P1482, and P1484.

The scan tool can engage the cooling fan clutch. This is done with the engine controls special function menu screen. To engage the cooling fan, It can take up to 2 minutes for a 100% command with the engine at 2000 RPM. The lower the engine speed, the longer it will take the fan to engage. To disengage the cooling fan, it can take up to 2 minutes with the engine at 2000 RPM. The lower the engine speed, the longer it will take to disengage. In lower ambient air temperatures the cooling fan will engage in less time, however, it will take longer to disengage due to the properties of the fluid vs. temperature.

Under certain conditions the cooling fan may be engaged at engine restart. They are as follows

1. The cooling fan was engaged at the time the engine was turned off
2. The fluid may bleed from the storage chamber into the fluid coupling of the cooling fan

Although the fan is commanded off at this time due to a cold start condition. This is the most likely time a vehicle driver will notice that the fan noise is excessive compared to normal engine starts with out cooling fan engaged. As the engine speed is increased the fan noise will be louder than before. These are normal conditions that can be very intermittent.

ENGINE COOLANT HOT IDLE ENGINE

The radio activates an audible warning as requested by the instrument panel cluster (IPC). The IPC sends a class 2 message to the radio indicating the chime duration of 4 pulses. The warning sounds and the appropriate indicator illuminates in the driver information center (DIC) when the following occurs

1. The IPC determines that the coolant temperature is greater than 125°C (257°F). The IPC receives a class 2 message from the PCM indicating coolant temperature.
2. The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.

The IPC turns OFF the engine coolant indicator when the engine coolant falls below 122°C (252°F).

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 1/3 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 jackets surrounding the cylinders, where the coolant 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 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, which are described below

1. The coolant
2. The radiator
3. The pressure cap
4. The coolant recovery system
5. The air baffles and seals

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, consisting of a core and 2 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 the core. The fins on the core transfer heat from the coolant passing through the tubes. As air passes between the fins, the air removes the heat and cools the coolant.

Pressure Cap

The pressure cap seals the cooling system, and contains a blow-off or pressure valve, and a vacuum or atmospheric valve. The pressure valve is held against the seat by a spring, which protects the radiator from excess cooling system pressure. The vacuum valve is held against the seat by a spring, which permits the opening of the valve to relieve the vacuum created in the cooling system as the coolant 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, the pressure valve opens, 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.

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 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. Its 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.

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.

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.