what color is burned ATF smoke, and other asst'd questions - PeachParts Mercedes-Benz Forum

JHZR2 · #1 10-17-2002, 02:50 PM

Hi,

I replaced my two fuel filters today. Filled the main screw on filter with ATF (type A, 75c variety from the local dollar general). After I started it, I got a faint whitish smoke out of the tailpipe. Is this normal? I am also trying to diagnose a possible headgasket problem, and this was my second known sighting of white smoke (the other time it was very cold, though).

For those who use the clear pre-filter, is it ever actually filled with fuel? I didnt use the hand pump becasue it gushes fuel, and since I filled the main with ATF, I figured it wouldnt be a problem. But there is air in the pre-filter, and In not sure if it ought to be so or not (The other filters Ive had in there were dealer installs and opaque).

Is it normal to see particulates in diesel fuel? I had never done a filter change for the fuel before, and when I removed the screw on filter, I noticed a few odd shaped small black particulates floating around on top. After running the car for a while, I noticed a few of the same inside the prefilter.

Since when is diesel fuel died blue? I thought it was a light yellow-amber color, however, in the interest of saving a few cents, I poured the fuel from the old filter into a clean glass jar to replace in the tank. The fuel was very dark in color, and when I held it up to the light, it seriously was a bluish color (very dark too). I hope this isnt a sign of metal wear in my pump, or means that I just poured everything the old filter had filtered out for the last 12k miles back into the fuel pump...

My car shakes when warm, but only when in neutral, at idle only. If I slightly rev it, to say 1000, it becomes perfectly smooth. Is this a good indication that I need to adjust the bolt on the IP?

Can someone explain the blowby test done by removing the oil filler cap? Every time in any car, new or old that I have opened up the cap, an oil vapor, or some sort of vapor comes out as a whitish smoke. I did it today just for kicks, and a lot of smoke came out. Is this something to worry about, or is this common?

Thanks for the help on any of these questions.

JMH

#2 10-17-2002, 03:03 PM

ATF smoke is white, the blue color fuel is normal coming from the filter. There is supposed to be fuel in the prefilter, but as far as I know they are not completly filled with fuel, or at least it's that way on my car.

One thing I would recomend not doing is cleaning the injectors with ATF. Spend the money and get some Lubro Moly Diesel Purge, this stuff works great. I would also not recomend dumping back the old fuel from the old filter back into the fuel tank.

psfred · #3 10-17-2002, 08:07 PM

White smoke is normal when starting a cold engine, and will be worse on ATF because it is somewhat "heavier" than diesel.

Don't use ATF, it doesn't do a thing for you. If it has zinc stearate in it, it will leave abrasive ash in the combustion chamber, too. Use a diesel additive. I don't know where the myth that transmission fluid was good for diesels came from, but the only thing it might to is be a better detergent for removing varnish. It burns like crap in a modern diesel, they aren't set up for high molecular weight oils, and any decent injector cleaner will do a better job of cleaning the fuel system.

Fill the filter with clean fuel or fuel treatment. You also need to replace the priming pump, as it will eventually leak air and cause starting/running problems from fuel starvation.

Small black specks usually mean algae in the tank -- you will eventually need to get it cleaned if more than a few show up between filter changes.

The fuel is not dyed any color -- the blue color is fluorescence of the polynuclear aromatic hydrocarbons in there, the yellow to brown color is indicative of the source of the crude oil used to make it. Off road (no road taxes paid) fuel is dyed red, gasoline is dyed red/gold.

Rough idle warm in neutral only suggests a bad engine mount more than a rack pin bolt -- that usually causes rough idle in gear only.

Peter