Assignment

The fuel filter does the job of removing any possible impurities from the fuel which could damage the fuel injection system or impair the flawless operation of the engine. Included in this, are not only solid foreign matter, but also, e.g., air and water. It should do this under the aspect of maximum environmental protection, that means, that the filters should have to be changed as seldom as possible to reduce the amount of refuse.

The above pictures show the latest development, at least at the moment, on the way to the fuel filter management. The replacement intervals are slowly approaching the one hundred thousand kilometer mark. The element to be exchanged is no longer a cartridge with a metal casing anymore. Nowadays, the lid is unscrewed, and a metal-free, easilier recycleable cartridge is exchanged.

Function

Two filter elements are used - for a passenger car seldom enough - parallel to each other. The filter elements to be exchanged no longer consist only of one filter layer, but several, also the single layers, in a star- shaped arrangement, from the outside inwards (air-flow direction), have become increasingly denser. Layers with a construction similar to synthetics (fiber glass) are also possible. These materials are capable, in the meantime, of trapping even the smallest of particles measuring no more than 5 micrometers (0,005 mm). The water separation has also been improved. From this we can see that all the newer injection systems, (Common Rail, Pump-nozzle) make higher demands on the filter system than former diesel engines.

The large amount of visible fuel-pipes arises from the various transport cycles of the diesel fuel. When the engine is cold, the not injected fuel is returned (at higher pumping pressure) directly to the filter and maintains a certain temperature to avoid the removal of paraffin and with it, an interruption of the supply. Vehicles with a filter-inflow heating are well protected against very cold winter conditions. With engines running at operation-temperature, an additional cooling on the way to the tank, is possible. 07/06

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