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Diesel fuel filter clogging

how do i fix the algae in the fuel tank of my mercedes benz 300d which clog up the small clear plastic fuel filter. the car slows down when the filter is clogged up and I bought 4 filters and just keeps replacing the clogged filter to get better speed. please help. Thanks.

You need to have the tank cleaned. You also likely need to use a more reliable fuel source.

The filters keep clogging, because of the algae or other problems. This seldom happens unless the fuel is old or contaminated. Any chance water might have gotten in the tank at your end?

This is a COMMON problem with marine diesels so if you live near the coast, you can find people who do tank cleaning and fuel filtering with little fuss. Inland, you will have to drop the fuel tank, dispose of the contaminated fuel, clean out the tank and put it all back together.

Marine supply houses sell fuel additives that prevent the growth of algae in fuel tanks…

You need to add a diesel fuel biocide such as this to prevent algae from forming in the fuel system.


Any heavy-duty truck parts store sells a product called “Killem” that eliminates the algae in diesel fuel. It’s toxic stuff, so read the directions first. It’s cheap, and it works.

Yes, the biocides work, but they don’t remove the clumps of dead algae that will continue to plug your fuel filters.

Yep, I think drop and clean the tank, then use preventive measures. I had about 20K on my Olds diesel and got a bad tankful. Plugged the filter in about 100 miles. After changing filters about five times, I finally just dropped the tank and dumped all the crap out and was fine after that.