WikedV12

Was under the CL65 this weekend cleaning up some old mess from a leaky hydraulic line and I had taken off all the plastic covers from under the car. I noticed a few small oil drips right where the transmission bell housing bolts to the motor. The oil drips looked very clean and I could not see where the drip could be coming from. I'm just hoping it's not from the rear main seal. Is it common for those to leak? I have not removed the intercoolers so maybe it's a leaky valve cover gasket. I just hope it's not related to the whine I've not been able to track down....

I ended up wiping everything clean. I almost felt like I was under my Dodge Cummins diesel as it has ALWAYS dripped oil. But that is too be expected with a Cummins....but not a Mercedes.

MooksM275

I have dealt with this and yes it could be from your main seal obviously due to the location of the leak underneath. I would also check your valve cover gaskets but I would say the leak is most likely coming from the cover between the two cylinder heads that runs the length of the block. The front of the cover extends over the cooling passages. The back of the cover has an integral o ring that is the main oil supply to the turbo oil feed lines. This o ring gets brittle and leaks causing oil to build up at the rear of the block and the cover can't handle that much oil so it leaks down the back of the block. The leak goes through the bell housing and looks like a main seal so be careful.

Best way to check is to lift intercoolers and look down at v of engine and rear of engine at top (between heads). If you see any oil there than that is the culprit. Problem is that this cover cannot be removed without removing cylinder heads (both of them). Sucks. In my opinion, given the condition of mine when I replaced it, I would say this will be a major problem for every single m275 as they age-just a matter of time. Some people can live with the leak so better just leave it alone but for me I had to fix it. Engine has to come out but can be a time to do other items that are needed which is what I did.

my symptoms were same as yours and I traced it finally by seeing oil at top of bell housing. After removing intake manifold it was very clear.

WikedV12

Thanks for the suggestions. I will check that this weekend. If it is the cover between the cylinder heads, are you saying it is ok to leave it alone? I don't have any plans to pull the engine anytime, so if that is the problem will it get a lot worse or will it just be an annoying leak that I can get use to like on my diesel? I'm asking because I can live with a small leak that is very hard to fix, but I can't live with a small leak that will lead to some big problem. Does this affect the oiling of the turbos at all?

I just hope my dream car does not turn into a nightmare......

HopefullyE63

Hey Wiked. I have the leak too. It seems to stay steady. I found out about 4k miles ago and just make it a habit to check the oil occasionally. It will get messy as dirt will stick to the oil etc. I dread having to take the engine out and may just part the car if it gets worse. Mine is a 2003 cl600 so it's a TT car.