Hello

I have an elusive oil leak on my 1988 560SL. I thought it was a rear main seal see photo. I have already done the following.

1) I pulled the transmission and inspected the seal and foud it to be dry.

2) I also inspected the back engine cover and found it to be wet but the wetness appeared to be comming from outside of the bell housing, possibly through the crank position sensor hole or the left side starter hole. I have not discounted the engine back cover but I did not remove it since the manual strongly advised against it unless absolutly necesary.

3) I have noticed the PS appears to be leaking but will not drip even with the steering wheel held hard over with the engine running. Of coarse nothing drips when I'm under it. Also oil on floor looks and feels like motor oil.

4) I am concerned about the rear of the cylinder head. My manuals have a schematic showing the head being feed at the rear. This seems to me to be a very unlikely place to leak oil. I cannot get a good visual inspection of this area. It does appear to be wet but not unusually so. I can get a reasonable look at the valve covers seals, they appear bone dry.

5) It's leaky enough to form a small 10" puddel in my garage after one or two days of use but I cant see any fluid levels deminishing from either the engine trans or PS pump.

I guess my question for the group is what is the most likely sorce of a leak in this area. Has the 560 been known to leak oil from the head? And also if I have to remove the rear cover what is a recommended sealer for this cover.

Thanks You
John Roncallo

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ck. while running, under the intake in between the valve cover w/ a small flaslight. When the heads leak, more than likely oil will collect in that valley under the intake. There, it will fill then run-off in a weep hole and come out a hole in the bell housing in front of the trans. I had this happen to my 380 prior to tearing it apart. Funny thing though, it ran ok despite the bad head gasket. Could just swap valve-cover gaskets and hope that was the problem too. If is is your head gasket, the leak will eventually become worse. Finally, if you degrease the area aroud the leakage, you may locate where the origin oil is coming from. Hope this helps. Les

I have a 1990 560sel that was leaking oil in the same general area. I did not think it was the valve cover but thought checking could not hurt.Thighten the right side and the leak stopped.

Sound like a good theory. I did try looking under the intake today with a drop light. I could not get a decent view of anything. Where do you look, from back with mirrors, from the top in between runners etc? Is my drop light too big for this inspection? I did get a good look at the valve covers and they appear very dry. This weekend I will pull the valve covers and hopefully put that issue to bed. It would be real nice if that turned out to be the problem but I'm not too hopeful. At least I will probably get a better look at the head with the covers out of the way.

Thanks for the reply
John Roncallo

M117s leak at the valve cover gasket down the back of the engine for some reason. Check also to see if you have an oil pressure sending unit on the rear of the left head (I have a mechanical gauge on the 280SE, a common leakage point).

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Do the easy stuff first (too late, you already pulled the tranny!!) and replace the rubber valve cover gaskets.

I am betting you have the dreaded head gasket leak though, higly prevalent on the rear left head (drivers side) and to some extent the right side, on the 116 and 117 engines. There is a oil return channel on the rear of both heads, the gaskets get petrified, lose their seal and can leak oil badly.

__________________
Chas

Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL

Got a Euro 500SEC right now.

OK I did the easy stuff . I looked at the valve cover gasket and it did not appear to have any problems. It really would have been a welcone sight to find a crack in the gasket. At this point my oil leak really is pointing to the cylinder head gasket. But before I go and rip it out does anyone have any good inspection technics to check the rear of the left head for oil leaks. Mirrors to use flashlights, where to look from etc.

Thank You
John Roncallo

On my 91 560SEL I have 2 head gasket leaks located at the rear corner on both sides. Very slight, not enough to cause alarming loss of oil ( I add about a quart every 1500 miles), but has had the problem for more than 2 years now. I have not thought of doing anything about it yet, except to monitor it via drips on the floor and loss of oil. I probably see one drip the size smaller than a dime each morning. I detected the exact location of the leaks by cleaning the engine with engine degreaser from under the car, wash it off, let it dry and drive it for about 50 miles, then went under the car. The source of the leaks could easily detected with all the sorrounding areas still dry..

My problem is not being able to see the head gasket to block joint at all. So even if it was clean I cant get a good look. Remember I have a 560SL the 560SEL probably has a bit more room to get a good look. I think at this point the only thing to do is pull the intake manifold and get a real look.

Thank You
John Roncallo