Blue Smoke - PeachParts Mercedes-Benz Forum

doppx006 · #1 01-31-2006, 05:19 PM

I purchased a 300D this late fall and have fixed it all up and I moved it the other day from one garage to another on the property and it was about 40 degrees out and every time I let this thing run it smokes blue at idle, I do not know if it will do it when I drive it or not, and it does it even when at full temp. I have a coupole of Ideas why, old fuel maybe, Hadnt been driven much for awhile and I dont think they ever ran the junk out of the engine on the freeway, it has 96K it is a 76 300D 115 I noticed once I changed all filters and fluids it smoked less, do you all think once the spring rolls around and i can run it do you think it will clear out or do you feel I might have a problem? and this a naturally aspirated engine. THnaks alot. I have no experience with how these engines operate so i do not know if this is normal, valves have been adjusted as well.

Wasuchi · #2 01-31-2006, 06:22 PM

I doubt you have much of a problem. If you haven't been driving it then it isn't getting up to full temperature (the coolant may be but the engine isn't). Anyway, it probably isn't completely burning all the fuel since it's not up to temp., Diesel engines don't like to sit, they're meant to go out and work hard every day. Now if it burns a lot of oil when you do drive it you might have a problem.

P.E.Haiges · #3 01-31-2006, 06:23 PM

dopp,

Smoking not due to old fuel. I have used fuel over 10 years old and there was no difference between that and new fuel.

It probably needs an Italian tune up after sitting for so long or some hot running with synthetic engine oil.

Don't expect to the synthetic oil to clean out the engine overnight. It took Castrol Syntec 3 years and 30,000 miles to clean my 300SD engine to improve the engine oil usage from 4 quarts in 10,000 miles to about 1 quart in 10,000 miles.

P E H

Diesel Giant · #4 01-31-2006, 06:32 PM

Diesel fuel or any petroleum fuel for that matter does go bad. However many factors will determine to what extent. Get the car out and put some fresh fuel in her and drive it for a week or so. Or just drain the tank and put new fuel filters on and then fresh fuel. Give her a diesel purge while you are at it.

t walgamuth · #5 01-31-2006, 10:40 PM

diesel really doesnt go bad unless it has water in it. if it has water it will grow fungi. that will show up in the small filter as black dots. then you need to get fungicide and treat the fuel for three tanks in a row. availbale at tractor truck or marine supply places.

the blue smoke can be oil from rings or valve seals or dribbling injectors.

good luck

tom w

P.E.Haiges · #6 02-01-2006, 09:16 AM

Tom W,

Diesel fuel will not automatically start to grow fungus. The fungus has to be introduced by fuel contaminated with fungus.

In using and storing Diesel for almost 40 years, I only had one car become contaminated with fungus. Somewhere along the road where I bought Diesel fuel, I got contaminated fuel and te fungus grew until it plugged the fuel tank strainer.

None of the fuel I had stored, some for 10 years or more, became contaminated. Treatment with Biobor killed the fungus I have had no further problems. But I still give that one car a Biobor treatment every year before I store it for the winter just in case some of the fungus survived.

P E H

DieselJim · #7 02-01-2006, 09:22 AM

Driving a neglected car makes a lot of difference. I saw rapid improvement in my old 300SD when driving daily in both oil usage and smoking. I used dino diesel rated oils changed often. All but the most modern diesels have some blue smoke. I saw a couple of 190D's on the freeway yesterday and they both were leaving some blue. I would not panic with blue smoke. Especially if you continue to see improvement.

White smoke is another matter. I saw an SD that was white smoking bad over a year ago on atlanta freeways. I have never seen that car again...

I smile when I see the puff of blue smoke when I put the hammer down on my 92 300D.

Good luck and enjoy that car!