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7 Diesel Fuel Filter Replacement Tips

A diesel fuel filter.

Diesel engines have different maintenance requirements from gasoline powered engines. Their combustion process is different, leaving diesel fuel more quickly and easily contaminated than gasoline. For this reason, diesel fuel filter replacement is an absolute requirement of regular maintenance on a diesel system.

Luckily, this is a job you can accomplish at home, and anyone familiar with replacing a gasoline filter can do it after brushing up on a few quick tips.

Study up

Read your owner’s manual for all the specifications of the job: location, parts, specs, maintenance intervals, etc. Intervals on replacement may vary depending on usage, but it’s always better to veer on the side of caution and change more regularly if you are unsure.

Know the Signs

Outside of normal changes, warning signs of a clogged fuel filter include a rough idle, hard start, loss of power uphill or under a load, and an engine that runs rough at low speeds but evens out at higher RPMs. Note that these might also be caused by other issues.

Prepare7 Tips for Changing Diesel Fuel Filters

Know what tools and parts you need to gather before you start. Most diesel systems have at least two fuel filters, a primary and a secondary, and some even go a step further and add in a fuel water separator. You’ll likely need hex wrenches, torque wrenches, a socket set, a flathead screwdriver, rags, a large drain pan and protective gear like goggles and gloves.

Avoid a Mess

It’s a dirty job, but there are a few tricks to reducing the splatter. For one, drain the filter first. If you’re working with a filter enclosed in a housing, remove the bowl from the filter housing, loosen it without taking it all the way off, and let that drain down. You could also remove the filter but hold it there long enough to collect the fuel that comes out.

O-Ring Replacement

O-rings are another important factor in preventing leaks. Remove the old O-ring (if you double them, they will leak), and then clean the area and nearby threads well, and make sure the new O-ring seats properly. Run a light layer of diesel fuel around the ring with your finger for lubrication to prevent binding as you tighten.


Grab your torque wrench. Too loose and the filter will leak. Too tight and components may bind or crack and leak. Start all threads by hand to prevent cross threading (clean the threads first to remove debris), but tighten according to the owner’s manual.

Get Pumped

You can prime some filters before installation. Other diesel systems have built-in methods of bleeding the air out once all filters are installed. Again, bleeding methods can be found in the manual. Either way, this is an important step that prevents vapor lock and ensures a smooth startup.

Changing the fuel filter on your diesel engine is a necessary part of maintenance, but it doesn’t have to be difficult. With the right tools and know-how, you can take care of this service task from the comfort of your own garage.

Check out all the diesel fuel filter products available on NAPAOnline, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on diesel fuel filter replacement, chat with a knowledgeable expert at your local NAPA Auto Parts store.

Photos courtesy of Blair Lampe.


Blair Lampe View All

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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