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Algae On My Racor

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Question: While performing routine maintenance on my Caterpillar C7, I was surprised to find a substance about the size of a quarter at the top of my Racor—it looked like algae. There was no water in the bowl, and the engine-mounted filter was found to be clean. My Cat runs fine now and I would like to keep it that way. I am getting a lot of suggestions from friends as to what this was. What’s yours? —Peter “Frank” Riley, Long Key, Florida


Professor Diesel: Without actually taking a look at the substance, it’s hard to say for sure. But my guess is that is was indeed algae. As you no doubt know, this stuff can plug up your filters in no time, stop your engine cold, and even cause serious damage to injectors and injection pumps.

Believe it or not, your Racor fuel-water separator is actually your second line of defense against algae. The first one is a tank of clean, top-quality diesel fuel that is as full as practically possible, so that the possibility of condensation is minimized. The more often you top off your tank—and stick with reputable places that pump lots of fuel—the fewer problems you’ll have.

Fuel additives can help, and I suggest you use one, as long as you use those recommended by your engine’s manufacturer. Periodic fuel polishing can also help, but be aware that old fuel may not burn correctly in your engine even after it’s been cleaned. In such cases it will have to be discarded for new fuel. And by the way, permanently mounted fuel polishers are gaining in popularity these days. You might think about installing one. Most can be operated both dockside and underway.

Finally, if this issue reoccurs consider having the fuel removed and cleaned while a professional cleans your tank via its inspection hatches. (If your tank doesn’t have access ports, have them installed.) This is expensive but the most effective option.

Professor Diesel is Larry Berlin, director of Mack Boring’s Training Services division.


This article originally appeared in the September 2010 issue of Power & Motoryacht magazine.