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5 Steps to Replace a Diesel Fuel Filter

A diesel engine powered truck

A diesel fuel filter ensures that fuel is clean before it reaches the injectors that feed the engine. If a filter is dirty or clogged, you may find it difficult to start your vehicle, or you may notice it idling roughly, perhaps sounding ready to stall. Most diesel engines have two fuel filters: The primary one is found somewhere on the fuel line between the fuel tank and the engine, while the secondary filter is typically located near the engine. Before colder weather settles in, it’s advisable to change both filters.

How to Change a Diesel Fuel FilterDiesel fuel filter FIL 600255NP

Before changing a diesel fuel filter, consult your owners manual for the replacement schedule. You may find normal and severe schedules, but choose the latter as most drivers take short trips under various hot and cold weather conditions that require more rigorous care. This means you will probably change your fuel filters once every 10,000 miles.

Reference the owners manual for information about each filter’s size — details you will need to have with you when visiting your automotive supply store for replacement parts. Here’s how to replace your diesel fuel filters:

  1. Locate the primary fuel filter. The first fuel filter will be on the fuel line and should be underneath the vehicle. Place an oil drain pan directly underneath the filter. With the proper tool in hand — usually an Allen wrench or a hex tool — remove the fuel filter housing plug, and allow the fuel to drain into the pan. Once completely drained, secure the plug in its place.
  2. Remove the primary fuel filter. Next, remove the first fuel filter, using a wrench and socket to loosen the cap. Once removed, extract the filter from its housing. Locate the O-ring on the cap, using a flathead screwdriver to separate it. Dispose of the old ring, as the new filter will come with a ring.
  3. Install a new fuel filter. Before installing a new fuel filter, use a clean cloth to wipe inside the housing and around the sealing surface. Next, place the new ring on the cap and secure it in place. Put the new filter inside the cap, and then secure both inside the housing. Tighten by hand, then finish tightening with a torque wrench.
  4. Replace the secondary fuel filter. The secondary fuel filter can be found adjacent to the engine. Move the oil drain pan directly underneath the plug, and repeat steps 1 through 3.
  5. Properly dispose of the old fuel filters and diesel fuel. Never dump the old diesel fuel down a drain or dispose of it with your trash. There are several places to recycle diesel fuel, depending on what’s available in your area — your municipality may have a suitable recycling center. After you complete the cleanup, update your maintenance records to show the date and mileage for when this work was accomplished, so you know when to do it again.

Diesel fuel systems depend on clean fuel to operate properly. The timely changing of fuel filters is critical to the smooth operation of your diesel-powered vehicle.

Check out all the fuel filters available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on diesel fuel filters, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Image courtesy of Wikimedia Commons.


Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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