i have a 1994 C280 95000 miles. I have a slow oil leak from the crankcase to the cooling system. No water in the oil as it is still clean and no foaming in 3000 mi. Using 5W 20 synthetic. In 1000 to 2000 miles i see maybe a 1/8 inch of oil on top of the coolant in the plastic overflow tank. No mixing or foaming it just lays there. Any ideas? Also i notice a slight growl sound when it is cold.

Likely a leaking/blown head gasket allowing oil into the cooling circuit.

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Be sure it is not tranny fluid into the radiator.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

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Sounds like a head gasket. Get thee to a mechanic ASAP! You can live with oil in the water for a bit, but if you get water in the oil, it's all over (don't ask me how I know)!

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'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles

Try some Barsleak. Sometimes it works pretty good.

Is it a solid film of oil across the top of the coolant tank?

Does it look like chocolate milk in the coolant tank? that is the real test for blown gaskets and action?

Are you saying that if you clean the coolant overflow it takes 1K to 2k miles for the 1/8 inch film to reappear?


I used to get a couple of drops of oil like scum in my C230, need to check if it is still there, MB dealer techs have told me it was normal occurance for my 95K mile engine.
Some techs I talked to who worked on asian peformance cars have said they see the same kind of scuz on those cars, and it is usual and not a sign of engine overhaul.

It is not like chocolate milk. After 1 to 2000 mi it looks like clean oil was poured in as there is no mixing. It is wierd as the water is not going into the oil. Could it be a leak in the oil cooler in the radiator?

That would be my conclusion if it were head gasket you would know it, it very well could be the radiator oil cooler.