Persistent engine oil leak-300E

My feeling is that I may not be alone on this one. My 91 300E, 3.0, has an oil leak at the point where head,block,bottom timing cover, and camshaft cover meet. I have tried all MB sealants and great care in replacing the camshaft cover, sealants, and gasket positioning a few times and it keeps coming back. Anybody with any tips here (sealant other than MB, cleaning agents for surface adhesion of sealants, etc) or it is a losing cause?

Did you use the correct MB sealant for this purpose. The correct one is translucent blue and smells more like plastic than the acetic acid smell of silicone seal. This sealant is very slippery and allows you to move the camshaft rearward while applying downward pressure without disturbing the bottom U seal.

You must clean the groove for the U seal thoroughly so that the vertical section will fit into the groove and hold in place. Clean the entire gasket sealing area on the lower cover, head and upper cover THOROUGHLY. Put the magic sealant everywhere, and gob it in the lower corners. Oil the shaft seal and carefully put it in place over the camshaft end with your fingernail while moving the cover rearward.

Mine leaked for a long time before having to remove it for other reasons. The leak was very minor, minor enough that it was just no problem in and of itself, but once I learned how to put the cover in place and what sealant to use, I found it no problem to seal it properly.

Best of luck,

Thanks Larry. Yes, I have cleaned the groove spotless, and everything else you refer to except the blue stuff. In fact, I was recommended by MB to use two different silicones (grey) bnut to no success. Would you have the number of the blue stuff handy?

Is the sealant Hylomar? I have even tried that one.

[andy day]

Blue Hylomar was develpoed by Rolls Royce during the late 1930's and was used with great success on their aero engines and is still use today on their most modern Trent series of fan engines. It is produced under licence all over the world and I too ( like RR ) have used it with great success during my time on motor cars. For the oil problem you mention, I would agree with Larry, good preparation is essential and I would venture to suggest you use the Hylomar PL32, medium compound, if of course you plan on another reseal . . . good luck.

Adam,

I have an incredibly buisy week, but I will try to remember to get the exact product info. for you.

Have a great day,

[Mike Murrell]

Adam:

This is straight out of the 103 Engine Manual, Job 01-212 - Removing, installing top front cover. According to the MB manual, two sealants are used:

001 989 61 20 10 - applied to left/right sides of the oil-free groove of the timing case cover(at joint to cylinder head).

002 989 00 20 10 - contact surfaces of front cover to cylinder head.

Mike, the sealant with the best success(about two years = 40k miles)was the 001 989 61 20 10 (last time I fixed it but just came back)I guess I'll try the same and be more careful cleaning the contact surfaces. Maybe brake cleaner and bamboo skewers to get at teh corners of the groove and do not forget to put a rag to stop anything from going into engine. Let you know later.