This may sound silly but...
My 1987 300SDL exhaust smells stronger after the engine is up to temp. Even if I have a high concentration of biodiesel, it smells normal when the engine is cold, gets more pungent after the engine is up to temp. Any ideas? Maybe a head gasket leaking coolant into the combustion chamber? The car does not smoke any more than normal. Oil consumption is not high at all. 172,000 miles.

John

 

does it do this while driving normally, or when pulling hard, like up a hill?

 

If your thinking coolent is the level going down or oil getting milky. What is your normal fuel hopefully not cooking oil