Your diesel engine is jerking, the fuel is not flowing correctly, and your car has difficulty starting. The diesel filter may be clogged. It filters out fuel particles and water (from condensation in the tank of diesel vehicles). Changing it is part of the car’s routine maintenance. It is an essential part of diesel cars, especially the most recent ones, which need particularly clean fuel at the level of the injectors (clogged injectors can be very expensive…).
Here is how to change a diesel filter.
1. Clear the access to the diesel filter
The diesel filter can be more or less accessible depending on the vehicle. Sometimes it’s on top of the engine block, or you’ll have to remove several components to get access. Refer to your vehicle’s Technical Service Manual for more information.
There are several very different types of fuel filters:
– Some can be removed. They consist of a tank that contains diesel fuel and a removable filter.
– Other diesel filters cannot be dismantled. They are in a closed room with fuel inlets, outlets, and electrical supplies (to power a diesel heater, for example).
2. Drain the fuel filter
Some fuel filters have a bleed screw.
– Place a container (or a cut plastic bottle) under the filter and install a large hose leading from the filter to the container.
– Open the bleed screw and allow the diesel fuel to drain through the drain plug.
Tip: If your filter does not have a drain plug, place a pan under the car to catch the diesel that will drain out when you remove the filter.
3. Disconnect the hoses from the fuel filter
Now disconnect the fuel filter by disconnecting the fuel inlet and outlet hoses. Pinch the hoses to prevent fuel from running all over the engine. Depending on the model of the vehicle and filter, you will also have to disconnect the electrical lugs (to maintain the fuel temperature).
Important: Be careful not to get particles into the fuel outlet hoses leading to the engine. Changing dirty injectors could cost you dearly.
4. Change the fuel filter
After removing all connections, remove the filter from its housing. Compare it with the new filter to ensure it is correct.
Depending on the type of filter, you will have to do different things:
– You may need to remove a part from the old filter for one-piece filters. Compare the new one to the old one. If a part appears missing from the new filter, retrieve it from the old one before discarding it.
– For multi-piece filters, clean the bowl with a lint-free cloth and fill it with clean diesel fuel.
New gaskets are included with the diesel filter you purchased. When refitting the new diesel filter, change your seals as you go along. This will ensure a better seal.
5. Reconnect the fuel filter
Once the filter is in place in its housing, proceed in the reverse order of disassembly and reconnect everything you removed to it:
– electrical lugs;
– fuel hoses (the inlet and outlet hoses are usually not the same diameter: you will not be able to confuse them).
Finally, remove the diesel that has fallen on the engine with brake cleaner or degreaser (fuel is corrosive to the hoses).
6. Restart the fuel pump
You must reprime the diesel pump for the fuel to flow back through the filter you just changed. You have two options:
– Re-prime the pump by hand with a bulb on the fuel line a little higher up. Pump for about ten minutes until you feel resistance on the priming pump.
– Use the electric pump that some vehicles are equipped with: turn on the ignition until the pump starts. Start the engine several times. If the engine stalls, wait a few seconds and then try again until it starts correctly.
Tip: while restarting, unscrew the air bleed screw (elsewhere on the diesel circuit) by a quarter turn so that the air can escape and put a cloth underneath. Remember to close the bleeder screw afterwards.
Important: Again, check your user manual for the procedure to follow for your specific vehicle.
7. Dispose of the old diesel filter at the waste disposal centre
The diesel filter is a very polluting part. Dispose of it at a waste disposal centre along with any fuel residues you may have collected, as well as any soiled rags.
Materials needed to change a diesel filter
Should you be looking for car servicing & repairs, one good address is Complete Mechanical Centre. Remember to share your experience in the comments below.