GENERAL INFORMATION

Engine cooling circuit with turbocharger 1.8 L 1 – radiator 2 – oil cooler 3 – coolant pump/thermostat 4 – cylinder head/block 5 – expansion tank 6 – turbocharger 7 – intake manifold 8 – heater core 9 – ATF cooler Only on vehicles with automatic transmission

The cooling circuit of other engines works on the same principle.

While the engine is cold, coolant circulates only in the cylinder head, the cylinder block and the heater core. When the coolant temperature rises, the thermostat opens the main cooling circuit. The continuously running pump directs coolant through the radiator. The coolant flows through the radiator from top to bottom and is cooled by the air flowing through it.

To improve cooling efficiency, the system has a temperature-controlled fan. It is controlled by a two-stage thermal switch screwed into the left side of the radiator expansion tank. When the coolant temperature is from +92° to 97°C, the thermal switch activates the first fan stage (half of full speed). If the coolant temperature rises from +99° to 105°C, the fan runs at full speed.

Because the fan does not run continuously, and because the coolant flow is regulated by the thermostat, the engine reaches operating temperature faster and fuel consumption is reduced.

CAUTION

The radiator fan may switch on with the ignition off. Due to heat soak in the engine compartment, the fan may switch on repeatedly. Remedy: Disconnect the radiator fan connector.