C12.9 Marine Engines Fuel System Primary Filter (Water Separator) Element - Replace Caterpillar

Fuel System Primary Filter (Water Separator) Element - Replace

Water in the fuel can cause the engine to run rough. Water in the fuel may cause an electronic unit injector to fail. If the fuel has been contaminated with water, the element should be changed before the regularly scheduled interval.

The primary filter/water separator also provides filtration to help extend the life of the secondary fuel filter. The element should be changed regularly.

------ WARNING! ------

Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. To help prevent possible injury, turn the start switch off when changing fuel filters or water separator elements. Clean up fuel spills immediately.


Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products.

Dispose of all fluids according to local regulations and mandates.


Do not allow dirt to enter the fuel system. Thoroughly clean the area around a fuel system component that will be disconnected. Fit a suitable cover over disconnected fuel system component.


Do not fill fuel filters with fuel before installing them. The fuel will not be filtered and could be contaminated. Contaminated fuel will cause accelerated wear to fuel system parts. The fuel system should be primed prior to starting the engine.

Illustration 1g03506426
(1) Drain valve
(2) Filter
(3) Filter base
(4) Water sensor

Note: Refer to Operation and Maintenance Manual, "General Hazard Information" for information that pertains to containing fluid spillage.

Note: Dispose of fluids according to local regulations.

  1. Turn drain valve (1) counterclockwise to open.

  2. Drain the water and sediment into a suitable container.

  3. Close the drain valve.

  4. Remove water sensor (4).

  5. Remove filter (2) from filter base (3). A filter wrench may be used to loosen the filter.

  6. Discard the used filter.

  7. Install a new filter into the filter base. Securely hand-tighten filter to base.

    Note: Instructions for the installation of the filter are printed on the side of each Cat spin-on filter.

  8. Install water sensor.

Fuel System Primary Filter (Water Separator) Element - Replace, complete.

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