Fuel cooling system. 1.9 TDI PD from VAG Group. Family of diesel engines with injection pump-injector

Fuel cooling system

High pressure heats unused fuel so much that it needs to be cooled before it can return to the fuel tank. The fuel cooler is located on the fuel filter. It cools the return fuel, thus preventing excessively hot fuel from entering the fuel tank and protecting the fuel level sensor G from damage.

Fuel cooling circuit

The heated fuel is returned from the injector pump through the fuel cooler. Its heat is transferred to the coolant in the cooling circuit of the fuel, which also undergoes a cooling process. Auxiliary water cooler lowers the coolant temperature in the fuel.

The V166 fuel cooler pump is an electric recirculation pump. It circulates the coolant in the fuel cooling circuit through the auxiliary water cooler and the fuel cooler. It is switched on by the J248 direct fuel injection control module via a relay and cools J445 fuel at 158 ° F (70 ° C).

The fuel cooling circuit is largely separated from the engine cooling circuit. This is necessary because the coolant temperature in the engine cooling circuit is too high to cool the fuel when the engine is running at operating temperature. The fuel cooling circuit is connected to the engine cooling circuit near the expansion tank. This makes it possible to refill the coolant to cool the fuel in the coolant expansion tank. Also, it allows you to compensate for changes in volume due to temperature fluctuations.

Read more about the family of diesel engines with injection pump-injector here .