Diesel fuel isn’t exactly clean. Diesel engines produce higher levels of particulates, microscopic bits of soot left over from the combustion process, than traditional gas-powered vehicles. These particulates harm human health and pollute the environment, but they can also damage your fuel system. The diesel fuel filter is designed to collect and remove these particles from the fuel to keep your engine clean. But the filter will eventually clog with particulate matter, which leads to dirtier fuel. That’s why it’s important to change your diesel fuel filters more often than you would if you were driving a passenger car.
Replacing your fuel filters is an important part of diesel maintenance. Learn when to replace your filters and what happens if you don’t.
What Are Diesel Fuel Filters?
Let’s start with the basics. All diesel fuel filters are designed to filter particulate matter, including soot, dirt, and other debris, out of the fuel your engine consumes. Removing this debris protects your diesel parts and the fuel system from wear and tear, including your fuel injectors as well as the combustion chamber. If they get exposed to dirty fuel, they will wear down that much faster and you will need to replace your diesel parts more often.
Unlike traditional fuel filters, diesel filters are shaped like a bowl with a drain for getting rid of excess water, so it doesn’t come in contact with your parts. The extra water can lead to oxidation and rust. The filter curves down as water collects at the bottom of the bowl. The water will then get drained out of the fuel as it makes its way to the water separator.
Most diesel filters also come with built-in heaters that increase the temperature of the fuel to reduce paraffins, which are caused by low temperatures. Paraffins will clog your filter and make it less effective over time.
Most diesel vehicles have two fuel filters, including a "primary" filter located between the fuel tank and the engine, which cleans the fuel before it gets to the fuel transfer pump, and a "secondary" filter near the engine, which gives the fuel a final cleaning before it gets to the fuel injectors.
How Often Should You Replace Your Diesel Fuel Filters?
It’s best to replace your diesel fuel filter every 10,000 to 25,000 miles. That’s quite a wide range and the timeframe all depends on how you use your diesel vehicle. Carrying heavy loads and using poor quality fuel will only put added pressure on your fuel filter. Check your owner’s manual for more information on how and when to change your diesel fuel filters. Don’t forget to drain the water separator as well to get rid of excess water.
You can reuse some high-quality fuel filters by cleaning them and putting them through an industrial blower, but most filters are designed to be replaced once they get dirty.
Replacing your diesel fuel filter is as simple as swapping out the old filter and installing a new one, but you’ll need a bit of experience under the hood to do the job yourself. You can always go to your local mechanic and request a fuel filter change. They shouldn’t charge you more than $150 to $200 for parts and labor. It’s always better to err on the side of caution and talk to a professional instead of biting off more than you can chew.
Refer to your owner’s manual to learn more about the fuel filters in your diesel engine, as each fuel system is unique. Start by locating the primary fuel filter and put an oil drain on the floor below to avoid making a mess. Use an Allen wrench or a hex tool to remove the filter housing plug, which will release oil into the pan. Loosen the cap on the filter with a wrench and remove the filter from its housing. Feel free to toss the old filter and O-ring if it's disposable. Wipe off the area around the filter housing before installing the new filter and O-ring. Reinstall the filter housing by hand and then tighten it with a wrench the rest of the way. You can repeat these steps with the secondary fuel filter. Just be sure to move the oil pan in the right place.
What Happens If You Don’t Change Your Diesel Fuel Filters?
If you decide to keep using the same diesel fuel filters past the recommended timeframe, they will eventually fill up with all kinds of dirt and debris. As more materials stick to the filter, the heater is less able to properly heat the fuel, which leads to more paraffins that only make the problem worse.
Once the filter is full, less fuel will be able to flow through the filter, which means less fuel will reach the engine. You will notice a gradual decline in fuel efficiency as well as a sudden loss of power behind the wheel. This can cause a stoppage in your fuel system. The built-up fuel will continue to put pressure on the various components of your fuel system, including the fuel injectors, fuel lines, fuel pump, and the injection pressure regulator valve, which sets the timing and pressure of the fuel being injected into the combustion chamber. The fuel injectors need to withstand large amounts of pressure because they open directly into the chamber. If the injectors get clogged with particulate matter, the engine will fail to start altogether.
The fuel runs throughout your engine, so you need to do your best to keep it as clean as possible. As the filters break down and your parts get clogged with soot and dirt, you’ll need to find replacement parts for diesel fuel systems to resolve the issue. The injectors and fuel lines tend to be the first to go when the filter needs to be replaced. Watch out for warning signs that your filter is past its prime, including a hard time starting the engine, trouble accelerating, strange sounds coming from the fuel pump, and frequent stalling.
If you notice some of these symptoms, don’t assume your diesel fuel filters are causing the problem. Some diesel fuel systems work better than others. For example, the IPR valve on the Powerstroke 6.0L engine is known to be faulty. Consider testing and replacing your 6.0 IPR valves before replacing your fuel filters.
Your diesel fuel filters are here to protect your engine from long-term wear and tear. Keep this information in mind to keep your vehicle going strong.
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