Coolant circuit

The coolant circuit is thermostatically controlled. While the engine is cold, coolant circulates only in the cylinder head and also in the engine block. As it warms up, the thermostat opens a large coolant circuit. In this case, the coolant is supplied by a constantly running water pump to the radiator. The coolant passes through the radiator from top to bottom and is cooled by the oncoming air flow passing between the radiator fins. A fan installed behind the radiator provides sufficient airflow, additionally sucking in the flow of oncoming air through the radiator.

A viscous coupling is located in the fan. As soon as the air coming from the radiator reaches a temperature of about +82°C, the bimetallic contact connects the viscous fan clutch. At the same time, the fan starts to work at higher speeds and provides an increase in air flow until the air temperature at the radiator outlet drops to about 460°C. After that, the viscous coupling is switched off and reduces the fan speed.

Due to the intermittent full turn on of the fan, the useful power of the engine is increased and fuel consumption is reduced.