FUEL FILTERS

Fuel Filters For Peterbilt Trucks

Fuel filtration is especially critical on modern high-pressure common rail diesel engines like the PACCAR MX-13 and Cummins X15 — injectors operating at 30,000+ PSI are precision components with extremely tight tolerances that contaminants will damage rapidly. A two-stage fuel filtration setup with a primary (water-separating) filter and a secondary (final) filter is standard on most Class 8 Peterbilts. We carry primary and secondary fuel filters from trusted brands including Fleetguard, Baldwin, and Donaldson for all major Peterbilt engine configurations.

Frequently asked questions about fuel filters

How often should fuel filters be changed on a Peterbilt?

Most OEM maintenance schedules call for fuel filter replacement every 25,000 miles under normal conditions, alongside the engine oil service. However, trucks operating in regions with lower-quality diesel, higher biodiesel blends, or fuel with elevated water content may see filters clog sooner. If you notice hard starting, rough idle, or power loss — especially under load — a restricted fuel filter is one of the first things to check before digging deeper into the fuel system.

What's the difference between a primary and secondary fuel filter?

The primary filter (often called the fuel/water separator) is the first stage and handles bulk water separation and coarser particulate removal. It typically has a bowl or drain valve to evacuate accumulated water. The secondary filter is a fine-micron final filter that removes smaller particles before fuel reaches the high-pressure pump and injectors. Both must be serviced — running only one stage or neglecting the secondary filter leaves the injection system vulnerable to damage.

What happens if water gets past the fuel filter on a Peterbilt?

Water in the fuel system causes injector corrosion, premature pump wear, and in severe cases, hydraulic lock in the combustion chamber if enough water enters a cylinder. Modern fuel systems with water-in-fuel sensors will illuminate a warning light when the separator bowl reaches capacity — draining the bowl promptly when the light comes on is a simple step that protects thousands of dollars of injection system components.

Other parts you might need

Shop filter kits for Peterbilt trucks