Operation CHARM: Car repair manuals for everyone.

Description






Engine Cooling

General
When the engine is running, the coolant is circulated around the engine cooling system by the coolant pump and the auxiliary coolant pump. From the outlet of the coolant pump, coolant flows through the cylinder block and cylinder heads, then into the outlet assembly. When the coolant is cold, the thermostat is closed and the coolant flows direct from the outlet assembly back to the coolant pump. When the coolant is warm, the thermostat is open and the coolant flows from the outlet assembly to the inlet of the coolant pump via the radiator upper hose, radiator, radiator lower hose and thermostat.
On vehicles without supercharger, when the thermostat is open, the coolant flow through the radiator lower hose generates a coolant flow through the engine oil cooler.
The EGR (exhaust gas recirculation) valve/throttle body and the heater core are on parallel circuits that are unaffected by the position of the thermostat. A constant flow of coolant is supplied to the EGR (exhaust gas recirculation) valve/throttle body from the outlet assembly. From the throttle body the coolant flows back to a dedicated inlet connection of the coolant pump. A constant flow of coolant is supplied to the heater core from the radiator upper hose. From the heater core outlet, the coolant flows back to the inlet of the coolant pump via the auxiliary coolant pump. For additional information, refer to Heating and Ventilation Description
Expansion and contraction of the coolant is accommodated by the hose connection between the expansion tank and the heater return hose.
If the coolant level in the expansion tank decreases below a predetermined value, the level sensor connects a ground to the instrument cluster, which activates the appropriate warning. For additional information, refer to Instrument Cluster Description
The cooling fan is operated by a fan control module integrated into the cooling fan motor. The fan control module regulates the voltage, and thus speed, of the cooling fan motor in response to a PWM (pulse width modulation) signal from the ECM (engine control module). The ECM (engine control module) calculates the required fan speed from the engine temperature, A/C (air conditioning) system pressure and transmission oil temperature. Under hot operating conditions, the fan may continue to operate for four minutes after the engine has been switched off. For additional information, refer to Electronic Engine Controls Description

Engine Cooling Flow Diagram (Vehicles Without Supercharger)









Engine Cooling Flow Diagram (Vehicles With Supercharger)









General
The primary components of the engine cooling system are the:
- Coolant pump.
- Thermostat.
- Radiator.
- Cooling fan.
- Expansion tank.
- Engine oil cooler.
- Connecting hoses and pipes.
The engine cooling system also supplies coolant to:
- The heater core. For additional information, refer to Heating and Ventilation Description
- The EGR (exhaust gas recirculation) cooler. For additional information, refer to Engine Emission Control Description
- The transmission oil cooler (vehicles without supercharger only). For additional information, refer to Transmission Cooling Description and Operation
In markets subject to very cold climatic conditions, an engine block heater is incorporated into the engine cooling system.

Coolant Pump









The coolant pump has a body that supports a shaft with an impeller attached to one end and a drive hub at the other. The body is attached to the front of the cylinder block with an adapter, which encloses the impeller to form the pumping chamber. The pump is driven by a pulley attached to the drive hub and driven by the accessory drive belt. For additional information, refer to Accessory Drive

Thermostat (Vehicles Without Supercharger)









Thermostat (Vehicles With Supercharger)









The thermostat is located in the outlet assembly, under the thermostat cover, and allows rapid engine warm-up by restricting coolant flow through the radiator when the engine is cold. The thermostat also assists in keeping the engine operating temperature within predetermined limits. On vehicles without supercharger, the thermostat begins to open at 88 - 92 °C (190 - 198 °F) and is fully open at 102 °C (216 °F). On vehicles with supercharger, the thermostat begins to open at 84 °C (183 °F) and is fully open at 98 °C (208 °F).

Radiator









The radiator is a cross flow type with an aluminum core and plastic end tanks. The radiator is located in the vehicle by locating spigots and supports integrated into the end tanks. The supports are installed in rubber bushes in the upper chassis rails. The locating spigots are installed in rubber bushes in the front end carrier. The transmission oil cooler and a drain plug are integrated into the LH (left-hand) end tank. Coolant inlet and outlet connections are incorporated into the RH (right-hand) and LH (left-hand) end tanks respectively.

Cooling Fan









An electric, variable speed cooling fan is installed in a shroud attached to the rear of the radiator. The cooling fan is operated by a fan control module, integrated into the electric motor, under the control of the ECM (engine control module). Two electrical connectors at the RH (right-hand) side of the shroud provide the interface between the cooling fan harness and the vehicle wiring.

Expansion Tank (Vehicles Without Supercharger)









Expansion Tank (Vehicles With Supercharger)









A pressurized coolant expansion tank system is used, which continuously separates the air from the cooling system and replenishes the system through a hose connected between the expansion tank and the heater return hose. A continuous vent into the expansion tank, through a hose connected to the outlet assembly, prevents air locks from forming in the cooling system.
On vehicles without supercharger, the expansion tank is installed behind the top right corner of the radiator. A filler cap, bleed screw and level sensor are incorporated into the expansion tank. MAX and MIN level markings are molded into the interior of the tank below the filler cap
On vehicles with supercharger, the expansion tank is installed on the LH (left-hand) front upper suspension housing. A filler cap and level sensor are incorporated into the expansion tank. A MAX level marking is molded into the interior of the tank below the filler cap. Cold fill levels are molded onto the exterior of the tank.
On all vehicles, the expansion tank provides the following functions:
- Service fill.
- Coolant expansion during warm-up.
- Air separation during operation.
- System pressurization by the filler cap.
The expansion tank has an air space of approximately 0.5 to 1 liter (1.06 to 2,11 US pints), above the MAX level, to allow for coolant expansion.

Engine Oil Cooler (Vehicles Without Supercharger Only)









The engine oil cooler is installed at the front of the engine sump, between the engine oil filter head and the engine oil filter. Engine oil is cooled as it flows back to the filter head from the filter. The coolant supply and return hoses for the engine oil cooler are connected to a T insert in the radiator lower hose. A restrictor in the T insert, between the two oil cooler connections, induces the flow of coolant through the oil cooler.

NOTE:
On vehicles with supercharger, there are two air cooled engine oil coolers.

Engine Block Heater









For vehicle markets subject to very cold climatic conditions, an engine block heater is installed in place of the cylinder block drain plug. The engine block heater is either a 110 V ac or 240 V ac electric heater element, depending on the market, which can be connected to a domestic power supply via a connector in the lower center grill of the front bumper.

Engine Coolant
The engine coolant is formulated to last for ten years or 240,000 km (150,000 miles). The coolant is silicate free and must not be mixed with conventional engine coolant.