April 2002 — By Mike Smith
Shine Your Diesel Oil
|Part 2: A polishing system can work when the engines are shut down.|
Finally, fuel filters don’t work unless the engine is running. When your boat’s sitting in the slip, the microbes are multiplying like rabbits in the bottom of the fuel tanks. When you finally do fire up the engines, the tanks have more gunk in them than they did when you shut down. But a polishing system can work when the engines are shut down.
Basically, a fuel polisher pulls diesel from the lowest level of the tank, circulates it through a cleaner by means of an electric pump and dedicated fuel lines, and pumps the clean fuel back into the top of the tank. Some fuel polishers can draw from and return to different tanks via a manifold, and some can feed the engine directly when it’s running but return fuel to the tanks when it’s not. Some cleaners employ ultrafine filters to remove sediment and other solids, microbes, and water; others use filterless dynamic fluid-mechanics technology. All but bare-bones systems include gauges or other indicators to warn you when the polisher’s filters need changing.
There are several ready-to-install fuel polishers on the market, geared for diesel-powered boats as small as 40 feet. Your first job is to pick between a filter or nonfilter system. There are more filter-based models to choose from, but filterless polishers don’t require element replacement. Whichever type you pick, run the polisher frequently so your diesel oil will make many circuits through the system, getting cleaner with every lap.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.