Electric water pump for TD diesel engines (Audi 80 B4)

When the engine is switched off, the circulation of the coolant stops, which can lead to overheating. To avoid this situation, an electric water pump helps to continue pumping the coolant through the circuit if the engine temperature was high at the time of switching off. At an engine temperature of approximately 115°C, the electric water pump is switched on by a corresponding thermal switch, which is installed on the cylinder head (see arrows in illustrations 13.0 and 13.0a).





The thermal switch switches off the pump at a temperature of approximately 110°C. The electric water pump only operates when the engine is switched off. The pump receives this information via the D+ terminal of the generator, which is de-energized when the engine is switched off. As a result, the electric water pump relay attracts the appropriate contact and directs current along the circuit from the additional fuse to the thermal switch.