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303-03-3 Engine Cooling 303-03-3 DESCRIPTION AND OPERATION Water Pump Engine Cooling A centrifugal-type water pump is mounted on the front Radiator of the cylinder block. The radiators are of the tube and fin-core type with A vane-type impeller supplies coolant through the tubes arranged for horizontal coolant flow. centrifugal action to the water pump oitlet port. Two header tanks, one at each end of the core If the pump is found to be faulty remove and discard provide uniform distribution of the coolant to the as it is of a sealed unit type which cannot be repaired. tubes. The radiator outlet port is connected to the Cooling System water pump inlet port. The radiator inlet port is connected to the coolant outlet housing of the engine, The cooling system operates as follows: thereby permitting coolant circulation through the Coolant flows through the radiator tubes and is radiator when the thermostat is open. cooled by air passing over the cooling fins Midway down the right hand side radiator header tank assisted by the radiator electric fans. is the coolant supply tank feed port, this connects the Coolant expands as the temperature and cooling system with the supply tank. The supply tank pressure rise in the system. provides a chamber to accommodate the expansion of the coolant as engine temperature increases. When the limiting system working pressure is reached, the pressure relief valve in the supply A small port is located at the top of the right hand side cap is lifted from its seat and allows coolant to tank. It is connected to the top of the supply tank. This flow through the supply tank overflow channel. port aids the self purging of air from the cooling system. The supply tank cap has a rubber seal on the underside to prevent leakage. An oil cooler is located in the radiator outlet header-tank to cool transmission fluid for automatic When the system temperature and pressure drop, transmission vehicles. the coolant contracts in volume and the pressure in the radiator is reduced. A draincock is located at the bottom of the left hand side tank. WARNING: Never remove the supply tank cap The coolant supply tank cap incorporates a 120 kPa under any conditions while the engine is (18 psi) pressure relief valve and vacuum valve. For operating. Failure to follow these instructions routine coolant level inspections the tank provides a could result in damage to the cooling system or quick visual method for determining the coolant level engine and/or personal injury. To avoid having without removing the tanks cap. scalding hot coolant or steam blow out of the Should the coolant level exceed the capacity of the supply tank, use extreme care when removing the header tank it is discharged out the overflow channel. supply tank cap from a hot supply tank. Wait until The header should not be overfilled. the engine has cooled, try squeezing the upper radiator hose to determine if the system is still With the engine cold the level of coolant in the supply under pressure. Then wrap a thick cloth around tank should between the max and min lines on the the supply tank cap and turn it slowly. Step back supply tank. while the pressure is released from the cooling Electric Fans system. When certain all the pressure has been released, The vehicle is fitted with dual electric fans controlled turn the supply tank cap (still with a cloth), and by three relays linked to the PCM module. remove it. During service operations, ensure that fan is not rotated in a direction opposing normal operation as WARNING: The engine radiator electric fans this may damage the motor (refer to arrow on fan may come on at any time without warning. blade). Disconnect battery ground cable before servicing Two operating modes are used (excluding OFF) - this will clear diagnostic trouble codes and depending on the status of the three relays adaptive learning. The vehicle must then be driven (determined by the PCM module). The different for 30 mins and idled for 15 mins to relearn. operating modes provide different cooling capabilities. (suggest using a 9 volt memory minder in the cigar lighter to retain keep alive memory). Refer to Wiring Diagrams section for a schematic of the Fan Control System. Cooling Maintenance CAUTION: When the ignition is in the ON Correct coolant level is essential for maximum position the fans may start without warning. circulation and adequate cooling. In addition, for the cooling system to perform its function it must receive proper care. This includes maintaining corrosion G97831 en |