Oil leak near turbo - 1987 300D - PeachParts Mercedes-Benz Forum

Marcb · #1 10-30-2003, 02:12 PM

Ok guys,

I replaced the vacuum pump in my 300D yesterday and I noticed it is pretty oily on the bottom-side of the car. I looked a bit closer and it appears that some type of leak is coming from the turbo area. I performed a search and haven't located anything definitive yet. I thought I would pick your mind and see what might be causing this.

Thanks.

#2 10-30-2003, 02:19 PM

The number one place most of these old diesels develop an oil leak is at the botton of the air cleaner. There is a short tube on the underside of the cleaner and it has an O ring there. Over time the O ring wears and oil leaks around that oil trap. It is supposed to trap the blow by and send it down and back into the pan.
Unbolt the air cleaner and replace the O ring first. Cheap repair. It could be coming from a few other places. Clean up that oil and grime and try to trace the leak.

gsxr · #3 10-30-2003, 03:26 PM

FYI - OldDies's info applies to the OM617 engine, not the OM603 used in the 1987 models. There are not many sources for oil leaks around the 603 turbo. Best bet is to pressure-wash that area at a coin-op car wash (bring a couple cans of Engine Brite) to get all the existing oil off. You may need to do this a couple times. Set the park brake and use the jack from the trunk to raise up the right/front corner of the car, this makes it easier to spray underneath. Oh, you'll need to take off the sound panels before you leave home, too.

Anyway, the common source with a Garrett turbo is the turbo itself. The seals start to fail and it seeps oil. The drain tube seals rarely leak (the older 617 engines were notorious for this, but the 60x turbos are not). Could be the timing chain tensioner seal, but I doubt it. Also there can be a minor leak the the forward/right corner of the cylinder head, at the block, right above the chain tensioner. This is common too. Simple fix is to tighten down the 2 head bolts at that corner 1/8 turn each, as there's a pressurized oil passage between them. This almost totally stopped that little leak on my one '87. Only other sources could be oil pan leak (I have that on my car- yuck), and the KKK turbo has a "controlled bleed" wastegate that allows some intake pressure - complete with PCV oil vapor - to blow out a tiny hole above the engine mount, making a mess over time (I have a KKK and my car does this - kind of annoying.)

Anyway - clean off the oily mess and narrow down the source, then we can help you stop the leak. BTW, disconnect and plug the two small vacuum lines to the EGR and ARV (on the turbo), if you haven't already!

underp2 · #4 02-26-2004, 06:30 PM

anyone know what the p/n is for the o-ring underneath the air cleaner?