P557004 | Genuine Paccar® Depth Coalescer Fuel Filtration Unit (for Kenworth, Peterbilt)

This system is the standard for PACCAR engines manufactured from 2010 to the present (EPA10, EPA13, EPA17, and EPA21).

• Engine Platforms:

  • PACCAR: MX-11 and MX-13.

  • Cummins: ISX15 and X15 (when equipped with the PACCAR chassis-mounted fuel module).

• Common Part Numbers:

  • PF46145 / K37-1029: The primary filter element for many MX engine configurations.

  • K37-1004 / K37-1011: Used in the PACCAR/Kenworth/Peterbilt fuel-water separator assemblies.

• Primary Vehicle Applications:

  • Kenworth: T680, T880, W900, T2000.

  • Peterbilt: 579, 567, 389, 587.

• Depth Filtration: Unlike a standard filter that traps dirt on its surface, the "Depth" media is thick and multi-layered. It captures contaminants throughout the entire thickness of the material, allowing it to hold more debris without restricting fuel flow.

• Coalescing Technology: This is the "magic" of the system. As diesel fuel passes through the coalescer layer, tiny, microscopic water molecules are forced to collide and join together (coalesce) into large droplets.

• Separation: Once the water droplets become heavy enough, they fall out of the fuel stream and settle into the collection bowl at the bottom of the filter housing, where they can be drained.

• Engine Protection: Modern high-pressure common rail (HPCR) injectors are extremely sensitive. Even a tiny amount of water can cause them to explode or corrode. This system ensures the fuel reaching the engine is 99% water-free.

• Water in Fuel Light: This is the most obvious sign. If the "Water in Fuel" (WIF) dashboard icon illuminates frequently, the coalescer has reached its capacity or the collection bowl is full.

• Low Fuel Rail Pressure: When the "Depth" media becomes saturated with contaminants, it restricts flow. You will experience a loss of power, especially under load or when climbing hills, often accompanied by fault codes for low rail pressure.

• Rough Idle and Surging: If the filter is partially clogged or has air leaks (often through a cracked filter bowl or a worn O-ring), the engine will hunt for a steady RPM at idle or "stumble" during acceleration.

• Hard Starting: If the coalescer is blocked, the engine has to crank longer to build the necessary pressure to start. In cold weather, trapped water in the filter can freeze, completely blocking fuel flow.

• Cloudy or Discolored Fuel: If you drain the fuel-water separator and the fuel looks milky or "cloudy" even after draining the water, the coalescing media has likely broken down and is no longer effectively separating the water from the fuel.