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Water pump
Water Pump The water pump is of a conventional design and is driven by the crankshaft pulley through the accessory drive belt. The water pump belt tension is maintained by an automatic drive belt tensioner. For additional information, refer to Accessory Drive Belt Tensioner - 2.7L Diesel (303-05)
Thermostat The thermostat is located in the thermostat housing and allows rapid engine warm-up by restricting coolant flow through the radiator below approximately 92°C (198°F). The thermostat also assists in keeping the engine operating temperature within predetermined limits.
When the engine is cold and the thermostat is closed, coolant flows from the water pump through the engine. It then returns to the water pump through the upper coolant hose.
When the engine is warm and the thermostat is open, coolant flows into the radiator through the upper coolant hose. It then returns to the water pump from the radiator through the lower coolant hose.
The heater core is on a parallel circuit and is unaffected by the position of the thermostat. Radiator The radiator is of aluminium construction with plastic end tanks. Foam seals are fitted to the radiator to prevent the cooling air from by passing the radiator core. A coolant drain plug is provided in the lower coolant end tank of the radiator for the draining of the coolant. The cooling fan shroud is attached to the radiator. Cooling Fan A single, variable speed cooling fan motor is attached to a fan shroud located behind the radiator. The speed is determined by the Engine Coolant Temperature (ECT) and the air conditioning 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. Coolant Recovery System A pressurized coolant expansion tank system is used which continuously separates the air from the cooling system and replenishes the system through the coolant expansion tank outlet hose, attached to the heater return hose.
A continuous vent from the engine and radiator to the coolant expansion tank prevents air locks from forming in the cooling system. |