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Draining Water from Diesel Fuel Filter

WATER IN FUEL FILTER: Draining off contaminants and water should get done on a regular basis.

It is so simple that you don't need to be a mechanic to achieve this important task - which takes only a few minutes.

There is an important reason to drain water and dirt from a diesel engine water separator. It needs doing because diesel fuel becomes contaminated easier than gasoline.

Diesel fuel absorbs water more 'readily' than gasoline or petroleum does. That causes corrosion in the fuel delivery system.

You might have this simple gadget attached to your diesel engine. If so, it works by collecting water from the fuel system. It is 'conveniently' called a diesel fuel water separator. It is usually found on or near to the fuel filter in the engine bay.

Draining the Fuel Water Separator

If you cannot find your engine's fuel water separator you can have one installed. They are not expensive to fit. The benefits of installing a water trap could save you a huge bill on mechanical repairs.

How to Drain Water from Fuel Filter: Diesel Engine Fuel Water SeparatorsAs most diesel owners know already, a vehicle fuel system requires careful attention. Draining water from a diesel fuel filter separator should be part of scheduled regular service intervals.

That means before if the engine starts to misfire. That will help to prevent engine damage from the buildup of dirt and water in the fuel.

There are some 'self-cleaning' water separators in use nowadays. But, many older diesels will need to have water and contaminants drained away 'manually'.

Follow these simple steps if you want to remove excess water from the fuel supply line.

How to Bleed Water from Diesel Fuel

  1. Try to position or hold an old jar under the small drain plug or tap which is actually called a petcock.
  2. The petcock is usually fitted to the fuel filter or the collection chamber of the fuel separator.
  3. After you loosen the plug or tap on the filter, the fuel - and water - should begin to flow out steadily.
  4. You may need to release the vent valve positioned at the top of the filter housing. This will allow the water to drain easier (it usually has a screwdriver slot in the head).
  5. Carefully unscrew the uppermost fuel pipe union connected to the filter casing if you cannot find a vent valve.
  6. Let the fluid drain until only clean pure diesel fuel flows out. Then, close the plug or tap and retighten the vent valve (or fuel pipe).
  7. Check the condition and quantity of water from the separator. You may consider obtaining diesel fuel from a different source if it contains a large amount of water.
  8. Having drained the diesel fuel water separator there may be one more job to do. You might need to renew the fuel filter if the engine still misfires or runs badly.

Importance of Draining Water from Diesel Fuel Filter

The big problem with water in diesel fuel is that internal corrosion blocks the diesel injectors. The result reduces the amount of fuel travelling into the engine combustion chambers. Diesel engine injector pumps and injectors have very small working clearances.

So, it is important to drain water in fuel filter of most diesel cars. You want to remove it before it reaches the diesel injection system. This simple task helps to move clean fuel through the supply line. In turn, that helps to keep your engine running smoothly.