My 300 SD is leaking oil from the turbo oil drain grommet, which I just replaced last week. I am pretty sure the hole where the O-ring and grommet sit was clean when I lubed them with oil and put 'em in. The gasket on the turbo had a small leak too but it is going away now. Now for the driver side of engine, There are some fumes (smell I can't place) and another oil leak I have tried cleaning the engine, oil filter housing, and injector pump to pinpoint the leak but to no avail. Does any one have any tips on how to stop these nerve racking and potentially pricey leaks? I have had to add almost 4 qts in the last few weeks. I am fairly familiar with diesel habits and a little drip here and there and some oil consumption is to be expected, but this is crazy.
-Zach

I am certainly familiar with 617 oil leaks.

On the left side of the engine the principal culprits:

1) Oil cooler line hoses. If these are wet where the hard line meets the hose, they are leaking. The entire underside of the SD, beneath the driver, was wet from long standing cooler line leaks.

2) The oil filter housing gasket. Over time, this gasket dries out and leaks.

3) The IP gasket. It takes a beating every time the IP is adjusted and it's a cheap paper gasket. PITA to change because you have to remove the IP to do it.

The leaks on the right side include the intake/exhaust manifold gasket and both the drain tubes.

The valve cover gasket should not be overlooked.

Are you sure the leak is not coming from the drain tube from the air filter? It is just inboard of the turbo drain tube on the oil pan. There is an o-ring which seals the tube to a nipple.

I've got a little oil leaking from the oil pressure sender on the left rear of the engine, sort of behind the oil filter housing. I'll get to it one of these days.

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The nipple thingy on the bottom of the air filter housing IS is the small tube but lacks the O-ring(I'll get one ASAP) as for some of the others, the oil cooler lines are cracked but not wet, the oil filter gasket is new with the MANN filter kit, so it should be fine, although, this is seemingly the spot where the fumes come from. IP has oil on the bottom of it, How do I change the paper gasket properly?
Valve cover gasket seems a little moist.

ps , when I wipe the oil off of the turbo oil return tube grommet I can see new oil seep out, I guess I will take it out and clean the area and try again.
Is it a bad idea to use black RTV gasket goop down there ?


thanks for the replies, Zach attack

I was thinking about the lower end of the drain tube from the air filter. But there is an o-ring on both ends. But the lower end tends to leak because the tube fits over the nipple. Not the best engineering.
The oil filter housing gasket that Brian mentioned is the paper gasket between the oil filter housing and the engine block, not the large o-ring at under the lid.

Some folks had problems recently with the metal tube portion of the turbo drain - I had to braze around the ends to get the tube airtight - this on a new part sold straight across the Mercedes dealer's parts counter. The flanged ends were either too short or incompletely pressed into the tube. Hope you aren't stuck with another R&R. Mack

I found the R&R part a little nerve racking, four hours total for a seemingly small job. But it was not unbearable. If I do it again it probably won't be as difficult. I have to look into the paper gasket. Thanks again. zach