How to Change a Diesel Fuel Filter

Many diesel engine vehicles feature two filters – a primary and a secondary. The former keeps gunk out of injectors while the latter filters grit away from injectors.

Change the Fuel Filter on Diesel Engines Before Beginning! – To prevent spilled diesel fuel and ensure safe removal of the filter. Keep an open container under it to collect any potential spills as you remove the filter.

Remove the Fuel Lines

Your car’s fuel filter is located between its fuel tank and engine, but finding it may be difficult. Consult the vehicle manual for guidance before placing a container beneath its old filter to protect from spillages as you remove it.

If your fuel line is connected to the filter by clips, bolts or “banjo bolts,” loosen them and take steps to unhook the old filter before installing your new one with proper orientation so fuel flows only one direction through it.

Metal X-type disconnect tool sets may also come in handy to disconnect fuel lines quickly. These tools feature male parts equipped with barbs and spring clips, and female parts with lip or rings you push into to open spring clips and allow the line to come loose from its source. Or simply pinching white tabs together before pulling can do the trick as well.

Drain the Fuel

One of the key steps when installing or changing out your diesel fuel filter is draining away all excess fuel. Doing this will make the task simpler and help prevent accidental releases of high-pressure fuel system pressure that could potentially cause injury, while also helping prevent vapor lock, which occurs when liquid fuel turns to gas before returning back into liquid form before reaching its rail.

Start by driving your vehicle until its tank is almost depleted; this will decrease the amount of fuel that needs to be drained, saving both time and effort. Raise and secure it on jack stands or jack stands, using blocks or chocks as needed, to prevent rolling while working underneath.

Wear safety glasses and locate the drain plug at the bottom of your fuel tank, typically round with a hex head. Use a ratchet and socket to loosen it carefully so as not to spill fuel from its drain tube.

Remove the Old Filter

Use a wrench or hex tool to loosen the screw clamp or bolts holding the filter in place, as well as any additional fuel filters on your vehicle. Also remove them. Fuel lines may release some gas when disconnecting them so be ready with a rag to catch any spillages from their connection points.

If the dirty filter is still attached to its cap, use a flathead screwdriver to dislodge it from it and install the new O-ring that comes with your new filter.

Compare your new filter to its old one to ensure they’re the same size and shape, looking out for any arrows that indicate direction of flow pointing toward your engine. Reconnect all fuel lines and replace clips on either end of the filter; if yours features wide alignment slots that correspond with larger “teeth” on its canister, make sure they align correctly.

Install the New Filter

Before loosening the filter, place oil-absorbing sheets or pads underneath it to absorb any potential fuel leakage that occurs; have something handy like a drip pan or rag ready to collect this spillage as soon as you loosen it.

When installing a new filter, be sure that its wide alignment slot and wide ‘tooth’ on the filter manager are aligned properly before carefully pushing in your new filter. Don’t twist or turn it as doing so could ruin its black sealing O-ring inside of its cap and lead to future complications.

Reinstall the clips or banjo bolt(s) used to secure the filter to the vehicle, reconnect fuel lines to it, and be careful when clamping rubber hoses — some may still contain fuel that could leak out if clamped too tightly. If your filter features an arrow that indicates flow direction, make sure that arrow points towards your engine. Retighten its cap by hand as using a wrench may damage its O-ring inside.