I have a 90 500SL with about 80,000 miles on it. Since buying the car in September, 2000, I have noticed on several occasions, light smoke coming out from under the car when hot and at idle in the driveway or traffic. Additionally, but only occassionally, after a commute of 65 miles from work to home, if I pull it into the garage and close the door, the garage fills with a smell of something burning, and a slight smokiness.....

I suspect oil leaking onto the manifold and burning off; I don't think it is coming from the brakes......The oil filler cap is tight. Since the engine is neatly covered with the MB cosmetic cover, I can't see what might be going on. Any ideas before I take it in for service? By the way, I have complained since purchase of a small oil leak which seems to be minor but constant....

Thanks in advance for any and all help.

Crankcase breather hose intact and connected to air filter housing? ..... Transmission fluid leak (input shaft seal)dripping on exhaust crossover pipe?


BTW, that "cosmetic cover" is actually the air filter housing, which is easily removed - no tools required:

1. Pop off the rectangular dust cover located in front of the air filter housing.

2. Remove the left & right air intake ducts.

3. Disconnect the crankcase breather hose (located at the right rear of the air filter housing) and move the hose that lies in the groove at the rear of the housing.

4. Lift up and pull forward to release the housing.

With the housing removed you can easily check the condition of the individual filters.

I had similar situation last year on my R129. The problem was the tech over filled my transmission fluid and after driving the car for a distance and everything got warmed up, the tranmission fluid would overflow and got burned off leaving slight smoke coming out of the hood. You may also try to put some newspapers under your car to see if you catch any kind of fluid leak (make sure you keep an eye on the paper, if the car is too hot the paper may catch on fire)if you still think something else is leaking. By the way, my car always smell hot. I don't know if its the characteristic of the vehicle or not.

95 R129
98 ML320

Since you mentioned a slight oil leak I conclude that the cause of the smoke is oil on the catalytic converter which is burning off.
The smoke will appear after sitting at idle for a minute or so after
a period of driving at highway speeds.... The cause is most likely
leaking valve cover seals, or the rear crankshaft seal needs replacing. The rear crankshaft seal would be the main source of
oil getting on the catalytic converter (or crossover exhaust pipe
behind the transmission bellhousing).... I had the same problem on my 560SL and was the result of a leaking rear crankshaft seal.

Check the transmission pan and pan gasket. I had a '92 500SL with me once that dripped trans fluid from the gasket onto the exhaust and made smoke. It only happened after a long drive and then coming to a standstill for more than a few minutes. What was happening was that while driving down the road, the wind was blowing the fluid backwards but while sitting, it was dripping right on the exhaust system.

Satish

I should have posted this sooner, but I HAVE solved the problem. It was a hole in the oil pan cover! I never actually saw it, but that was the source of fluid leaking on the hot pipes, causing the smoke.