Coolant circulation

The cooling system consists mainly of a radiator, a coolant pump. thermostat and fan.

Coolant circulation is controlled by a thermostat. While the engine is cold, the coolant circulates only in the crankcase and the heat exchanger of the heating system. When the fluid is heated, the thermostat directs the fluid through the radiator. The coolant is circulated by a pump driven by a V-belt. The coolant flows through the radiator from top to bottom and is cooled by the air flow passing through the radiator fins, which occurs when the car is moving.

For ONS and V6 engines, the fan speed is controlled by a viscous clutch, which is controlled by a thermal switch located in the fan motor stage. Thus, with the rotating crankshaft of the engine, the fan does not work constantly. and only turns on when needed. The fan speed depends only on the engine temperature and is independent of the crankshaft speed. In any case, the fan speed cannot exceed the crankshaft speed.

The diesel engine fan is also driven by a V-belt, but it is switched on through an electromagnetic clutch controlled by a thermal switch.

For a 4-cylinder DOHC engine, additional cooling of the liquid in the radiator is carried out using an electric fan. As soon as the temperature of the coolant rises, the thermal switch activates the fan motor via a relay. When the coolant temperature drops, the thermal switch automatically turns off the fan motor.

The expansion tank is a container that contains a supply of coolant. The reservoir compensates for the change in the volume of the coolant when it is heated in the engine and cooled after the engine is stopped. This ensures that the cooling system is always filled with liquid and ensures efficient engine cooling. The cooling system can only be filled with liquid through the expansion tank.

Warning: When the engine is stopped and the ignition is turned on, the electric cooling fan of the 4-cylinder DOHC engine may turn on automatically. Due to the heat build-up in the engine compartment, this can happen repeatedly. Therefore, when working in the engine compartment, you must always be prepared for the unexpected activation of the fan. Unless the nature of the work being carried out in the engine compartment so requires, the ignition must always be switched off.