The traditional best practice for fuel filter replacement called for 30,000 mile change intervals. It didn’t matter so much if someone was driving a gas or diesel fueled vehicle – the fuel filter had to be watched either way. As automotive technology has evolved and fuel has become cleaner, change intervals have been extended dramatically for gas filters. In fact, the change interval can be stretched to between 60,000 and 90,000 miles today. Some manufacturers of gas engines no longer recommend changing the fuel filter at all. However, for anyone driving a diesel-powered vehicle, these guidelines for changing fuel filters do not apply.
As a professional installer, it’s important to know that some of your customers may not understand why diesel fuel filters are different.
Clean fuel is essential for all diesel fuel systems. The purpose of a diesel fuel filter is to ensure that fuel is clean before it gets to the injectors. Modern diesel fuel injection systems are precision engineered with extremely low tolerances. These systems create a great deal of heat and rely on an unobstructed fuel flow to keep the fuel pump and injectors cool. Due to these lower tolerances in today’s systems, impurities are more likely to cause failures and costly repairs. When a fuel filter becomes clogged due to contaminant build-up, flow is restricted, which leads to increased heat and pressure. This added pressure can cause a filter to fail, which means it could send contaminants directly into the injection system. As you can imagine, contaminants passing through the injection system can wreak havoc on the performance of the fuel injection system. It doesn’t have to be this way!
The symptoms of a clogged diesel fuel filter can display themselves in the way that the diesel engine starts and runs. In the case of a clogged diesel fuel filter, the engine will likely start to idle rough and perhaps sound like it is going to stall. This is especially true when cold. Once heated up, the engine may sound like it is choking because there isn’t enough fuel getting into the engine’s fuel injectors. Engine sputtering, or missing out during acceleration, is a common symptom of a clogged diesel fuel filter as well. In this scenario, the filter has collected too much dirt and debris and isn’t allowing enough fuel to pass through to the combustion chamber of the engine. Finally, a highly clogged filter will impact whether or not an engine will start. This means that the engine turns over, but does not start – behaving as if it is out of fuel even when there may be plenty of fuel in the tank.
The easiest way to prevent problems in the diesel fuel system is to make sure that the fuel filter is changed at regular intervals. Manufacturer recommendations might vary slightly from one vehicle to the next, but a good rule of thumb is every 10,000 miles. By most maintenance schedules, this would amount to severe driving conditions. If a customer asks why it’s a good idea to go by the severe schedule, explain that most people don’t actually drive in ideal conditions. Regions that experience extremely high temperatures are susceptible because added heat increases the risk of contaminant build up. On the flipside, vehicles driven in regions that experience routinely cold temperatures are susceptible to diesel fuel gelling, which is as bad as it sounds and definitely not good for the health of a fuel filter.
As a professional installer, being prepared to explain to your customer the proper maintenance required for the fuel system on a diesel engine is a critical aspect of your business. Fuel filter service is probably the most significant part of that maintenance. Diesel fuel filters are different and knowing the difference provides you with a differentiating competitive advantage.