2021 Ram 3500 Fuel Filter Water Separator Replacement Cost

Diesel and marine engines use specialized fuel filters that not only catch debris from the fuel tank, but they trap water that has been mixed into the fuel - or emulsified. Since diesel fuel is much less volatile than gasoline, small amounts of water in diesel fuel will not be burned off inside the engine's combustion chamber, but it will actually cause the diesel to run poorly. This filter and separator unit solves that issue. Also, water in the diesel engine can cause fracturing of metallic components, excessive wear of tightly clearanced parts, and corrosion, for example.

When fuel is pumped out of the fuel tank, it moves through the main supply line toward the diesel engine. Before the fuel can reach the high pressure fuel pump it is intercepted by the fuel filter and water separator. The water flows into the filter with the fuel, but the heavy water is retained in the bottom of the filter housing, while the lighter fuel will be passed on through the main supply line. The water in the filter must be drained periodically for some types of filter housings, but many require the replacement of the fuel and water separator each time the diesel engine is serviced.

When the fuel the engine is getting is contaminated with water, the diesel engine will begin to perform sluggishly, it may misfire, or it may not start and run. This is because too much water built up inside the fuel and water separator will cause the water to run into the engine with the fuel. The high pressure fuel pump will pressurize the fuel and water, and the injectors will spray it into the combustion chambers. Once in the combustion chambers, the diesel fuel will ignite, but the water will not. The water may evaporate into steam, but otherwise it is a hinderance to the normal operation of the engine.