Dirty fuel causes the majority of marine diesel problems. To ensure clean fuel, take the following precautions:
- Adequately filter everything that goes into the tank. If you are adding fuel from dubious sources, use a Baja filter or water-separating fuel filter funnel.
- Take one or more fuel samples from the base of all fuel tanks at least once a year to remove any sediment and water, or employ a commercial fuel-polishing service.
- Change the primary fuel filter at the specified intervals, and clean the tank if the filter is dirty.
- Change the secondary filter at the specified intervals. If the filter is dirty, clean the primary filter and the tank, and check the filter screen in the lift pump.
- Change the air filter at the prescribed intervals. (Many small diesels don’t have air filters.)
- Periodically tighten the alternator belt. It should depress no more than one-half inch at the center of the longest belt run under moderate finger pressure.
- Check the heat exchanger for a sacrificial zinc anode. (Many modern diesels don’t have zinc anodes.) If present, inspect it monthly until the rate of zinc loss is established. Replace the anode when it is no more than half gone.
To learn more, take the Engine Maintenance course at a squadron near you.