damn front main seal

[TheDon04]

So I took the cabriolet to get the front main taken care of since it was dripping oil. Well after a fun day of replacing it and driving home i look under to check for leaks and its leaking, worse than before..

ridiculous!

so... what do I do? I used a brand new OEM part from a dealership and had it installed by an Independent.


someone on another forum mentioned if it had a groove that a brass sleeve or something would be needed to be put over the crank snout so it will seal properly. There was a very small grove where the seal would ride and it had carbon deposited in it.

[J. M. van Swaay]

MB has two part numbers listed for the front crank seal. One is the original type seal the other is a "repair" seal. The repair seal repositions the seal surface slightly when compared to the original seal. If the pulley assembly has a wear groove and you install a new original type seal, it will most likely leak..... Also, if the seal surface on the pulley assembly is pitted or damaged, niether part will seal correctly.

J. M. van Swaay

[augapfel]

Are you absolutely sure that the oil is leaking from the crankshaft seal? 82k miles is not a lot of miles; the harmonic balancer hub shouldn't be grooved badly enough to be allowing leakage. A couple of my 88s have 200k miles + and aren't leaking at the crank seal.
Excessive crankcase pressure could be pushing oil out at a good seal. Hate to say it but a cylinder leakage test may be in order.

[necromancer]

I recently had my front seal leak copious amounts of oil.

My fault entirely. I had the engine oil topped up and I'm certain that it foamed and blew out the seal. Fortunately, after re-filling the oil to a proper level it looks like oil isn't leaking from there anymore so I guess the seal can "reset itself" to some extent depending on how new/old it is. My front seal was replaced when the head gasket was done about 35k miles ago.