Quicksilver Diesel Fuel/Water Separating Filter for MerCruiser 2.8L–4.2L – #35-807256T

For later versions of MerCruiser’s diesel engines (post-late ’90s), the Quicksilver 807256T spin-on water-separating filter was introduced to replace the older cartridge element. If your MerCruiser 2.8L, 3.0L, 3.6L, or 4.2L diesel has a serial number above certain cutoffs (indicating an updated fuel system), this is the correct filter. It screws directly onto the fuel module and integrates both filtration and water separation in one. The advantage of this style is easier changes and a larger filtering surface area. The filter effectively stops any gunk – from rust flakes to micro-particles – and separates out water droplets that can get into diesel. This is critical for protecting high-pressure fuel pumps and injectors, especially in the common-rail or advanced D-Tronic systems these engines use. It’s recommended to change the filter at manufacturer-specified intervals (usually yearly or ~150–200 hours for diesels). The new design makes that task simple – there’s no messy element to handle; you just spin off the old filter and spin on the new one. The result is less downtime, a cleaner fuel system, and an engine ready for long hauls.

• Expanded Compatibility: The 807256T filter is part of a standardized family of filters also used by other diesel engine makes (for instance, some Cummins or Yanmar models have similar filters). For MerCruiser, however, this is the official filter. If your engine has been modernized (for example, a 2.8L with an electronic control upgrade, known as QSD 2.8), it will use this filter type.
• Extreme Use: Many MerCruiser diesels end up in boats for serious duty – e.g., rescue RIBs, workboats, or long-range yachts. This filter has been proven in such conditions: high-RPM vibrations, possible emulsified fuel (from biodiesel or long storage). The metal canister withstands shocks and is sealed to prevent air ingress (which could stall the engine). The internal media doesn’t break down from diesel additives or bio-components.
• Advantage over Old Design: The older filters (35-19486) were inserts requiring disassembly of a housing. The 35-807256T is an all-in-one module – it saves time during service and reduces the risk of assembly errors (e.g., mis-seated gaskets). This is important for crews who self-service their equipment – fewer steps, less chance of leaks.
• Fuel Reliability: Diesel engines are workhorses and typically more forgiving on fuel, but water remains their #1 enemy. With this filter, the chance of water reaching the pump is greatly reduced – water can cause corrosion or sudden stoppage. This is especially crucial in cold climates (water + diesel = ice crystals that clog the system).
• Quicksilver Quality Guarantee: This OEM filter has passed all compatibility tests with MerCruiser. Its ability to separate a high percentage of water (usually >95%) and filter particles down to 10 microns means it meets factory fuel cleanliness specs. Using genuine filters also keeps you in line with warranty requirements if your engine is still under factory or extended warranty.