87 300D Significant Oil Leak (sometimes)

Cylinder head gasket.

Could be a blown "O" ring in the oil return line from the turbo to the oil pan. How may miles are on the engine?

Over 250K miles on engine.

..............Scott

The turbo oil return line seal is in my experience the biggest source of oil leaks on these engines. It's probably original to the car and rubber just don't last that long; it should probably be replaced on principle. At the risk of sounding snotty a mechanic familiar with these cars would now this: they all leak from there at some point.

Mine (turbo return line) is actually leaking on my 84 300D. Its actually the only thing dripping oil on the entire engine. (262k miles on it) I bought the replacement O-rings, and lower rubber gasket, but how the heck do you get that thing off? The only place it is mentioned in the Haynes manual is when you are removing the turbo. Can I do this repair with the turbo still on the car? If not, how big of a pain is it to remove the turbo? (i.e. Am I gonna make things worse if I take the entire turbo off to fix this leak?)

Its leaking less than a quart for the 2500 miles that I have had it.

It's probably possible with the turbo still on but I sure wouldn't do it and it's not too hard to remove. The trick to gettinf the old one seal out is to put a hose clame around it, compress then pull it out. It's still hard, and hard to get back in though... but doable.

Thanks for the reply Richard. I am getting things in order to do the repair soon, so hopefully everything will go off (and on) well. Are there any other seals, gaskets, etc. that I would need for this replacement? (As in for the oil supply line, or manifold connection.)

Patience, hard liquor and/or drugs helps. It's really a pig of a job. You'll need a manifold gaskets.