smoke and ATF...

[jan lauwers]

Gentlemen.

My engine and AT were rebuild 2 years ago. After that, in Sept 2019, I took my car into a restauration shop, this time for the body. When I went in there, the car drove beautifully, but it looked bad! Since this week, I have it back. Now it looks stunning, it still drives greatly, BUT: it smokes badly. During the body restauration (which lasted 18 months) I noticed that the car had started to leak ATF. The location of this leak is at the point where the cable of the tach goes in the AT.

I have looked on this forum for possible causes of the smoke, and I learned that a failing modulator diaphragm on the AT  is a potential cause. This may be a stupid question now, but I am putting one and one together... I have an ATF leak AND a lot of white smoke.., after 18 months of idle time. Could the 2 problems be linked?

The guy who rebuilt the tranny said about the leak: give it some it some mileage, because the seals will have gotten hard as a consequence of the 18 months standstill. The guy who rebuilt the engine said the same about the white smoke,: put some mileage on the car and the smoke may go away. BUT... I am sitting here and thinking that perhaps there is a link between the 2 probs.

Could that make sense?
Thanks gentlemen

Jan

[FGN59]

Hello,
I bought my 280SL after a complete engine restauration by the PO. The car then sat for about 6 months in a cold place, being started only occasionally for very short periods of time. As a result, there was a lot of condensation accumulated in the exhaust pipes and mufflers. When I finally took it on the road, after it had gotten to normal operating temperature, it was belching a huge white exhaust cloud, from the water in the exhaust line being heated to vapour. This lasted for 30 or 40 Kms driven at moderate speed, and finally ended when there was no more humidity in the exhaust (fortunately it is a stainless steel exhaust line). Since then, I’ve never had it happen again. Maybe it is the same phenomenon for you?

The colour and the smell of the smoke can tell you a lot. In my case, pure white smoke, no odour at all, and a clear feel of humidity coming from the exhaust pipes meant it was water vapour. It could have been a coolant leak, but the cooling system was not missing any fluid, the car did not run hot, everything else was normal.

[jan lauwers]

Thanks for your reaction Francois...

I have done some 40 kms now I guess and I have a feeling it is not steam coming out. Time will tell... Need to seek some professional help I suppose.

Jan

[jan lauwers]

I have now noticed that there is no smoke at cold start... smoke only becomes apparent as soon as the engine is starting to heat up... (also at idle). 
Help and suggestions welcome please.

Jan

[Cees Klumper]

Maybe check the level of the automatic transmission fluid, to see whether it is being burnt up and that is what is causing the smoke.

I don't think the ATF leak at the speedo cable attachment point is related to the smoking. At least, if that smoke is coming out of the exhaust, rather than fluid that is leaking externally burning off onto the outside of the hot exhaust. If the smoke is coming out of the exhaust, then it's not an external oil/ATF leak, I would say.

[jan lauwers]

Thanks Cees

[jan lauwers]

Hello Gentlemen,

Thought I'd just share my happiness and learning for the benefit of the group here!

The (blue) smoke problem has been solved! Theories were: Stuck piston springs after the engine had stood idle for a year, or ATF being sucked in by the engine. None of the two was correct. The cause was in a failing plastic seal on one of the valve shafts. (see attached pics). These seals had been renewed during the full revision of the engine...but.. Still! I am very happy, this was a low cost repair for what was a big nuisance.

Oh BTW...my restoration, after many years, is finished now. Haleluja... I am the proud owner of a Pagoda that looks like new!

Jan

[johnk]

How about some pics of your car now that it’s done?

[Pawel66]

Happy to hear it ended up this way!

I am very curious how the diagnosis was done to nail the issue.

[jan lauwers]

Hi Pawel,

As I said, the first assumption was: stuck piston springs, since the engine had not run for over a year due to the body restoration. That proved wrong after some 500 kms or so. My mechanic, who had done the engine revision, then considered ATF, even though he said it is unlikely, but a simple test was to disconnect the vacuum tube to close off the inlet with his hand to see if the smoke would stop. That was not the case, so he then concluded that it had to be motor oil and assumed it would be a failing plastic seal. He was right!

John,

I will certainly post pics here of the finished car... just waiting for a sunny day.

Jan

[Pawel66]

Thank you!

[Benz Dr.]

Burning ATF is quite different than oil smoke. Even a small amount of ATF will produce vast clouds of white smoke. Oil smoke is darker in color and has a stronger smell.