Hey,

I ran low on fuel so the light came one. No biggie. Coincidently I checked under the hood to try to fix my shaking (posted in another thread), I saw that my secondary fuel filter was blackish. No biggie again. I took out a brand new filter and changed them over. The fuel that went in was again blackish in color. I'm kind of puzzled as there is no crud except the color change. Is it just all the dirt from my fuel tank or is it algae ? I change my filter every oil change so that other used filter wasn't that bad.

Oh yeh...when i poured the diesel out of the old filter it looked new again.

Thanks

__________________
Audi TT

Your tank has algae in it. You will need any algae diesel fuel treatment. Do a search this has been discussed quite a bit.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
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2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
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Fuel usually looks yellow in the filter. If you look at it in the air, filling etc., it has a purpleish color to it.

*Deep breath* Ahhhhhh, nothing smells better than diesel fresh from the pump.

Kamil,

I think you have the filters mixed up, The primary is the small inline filter you can see thru. The secondary filter is the "can" filter. I know this seems wrong but I think are named by the order in which the fuel goes thru them.

You are really wasting your money changing fuel filters so often. Read my dissertation on why a used filter actually works better. Find it with the search feature. If you have an fungus (its not algae), only a biocide will kill the fungus.

P E H

I spent mostof my life in Virginia and diesel fuel there is yellow in color. However, the last few years while living in Green Bay, WI, the diesel there seems to be less yellow and more clear in the winter months. Likely because of winterizing.

Regarding the issue of strainers and fuel filters, I think that removing the strainer from the tank and cleaning it must be one of the easiest and best things you can do to maintain a good quality fuel environment in the tank. Changing the filters is obviously a great idea as well. Especially when you do it at least once a year. Was talking recently with a good reliable non-dealer Mercedes shop owner in NC recently and he said that anytime you suspect bacteria growth in the talk (black gooey stuff) the best solution is that while you have the strainer off the bottom of the tank to pour 3-4 gallons of gasoline through the fuel filler and let it run directly through the tank thus killing the bacteria thoroughly.

I actually used to have more cold weather starting and running problems when living in Virginia (Yes, it actually does get cold there, especially in the mountains) than in Wisconsin because of the automatic fuel winterizing that takes place there.

Hope this helps.

Ira North
Green Bay, WI

Ira,

Your non Merceres shop owner's procedure of pouring gasoine thru the tank of a Diesel to remove fungus is worth about half way between diddly and squat. Even if the gasoline did kill the fungus, which I doubt it does, the gas will not get thru the fuel system or even on the sides and top of the fuel tank.

My tank mounted fuel strainer was clogged with fungus. I tried cleaning the strainer with gasoline and none of the fungus disolved in the gasoline. Therefore, pouring gasoline thru a tank with the strainer removed will do next to nothing because the fungis is not soluable in gasoline.

The only way to rid a fuel system that is contaminated with fungus is to use a biocide that circulates thru the entire fuel system to kill the fungus.

I don't agree that it is a good idea to change fuel filters either unless it is necessary. If the filters pass enough fuel for the engine to develope full power, the filters do not have to be changed. In fact, filters that are partially filled with with dirt/whatever, actually restrict smaller particles from passing thru them. Thus they filter better than new filters.

P E H