I'm trying to finish the head gasket job on my '91 300E 2.6 today and one of the parts I bought was a "timing cover O-ring". It's small, about a 1/4" in diameter and thin. I came across no such o-ring when disassembling. I only took the top cover off. I replaced the fan bearing bracket and while I was at the MB dealer the parts guy said I would need an o-ring when I installed the bracket. I assumed this was the o-ring I had since the bracket fits to the timing cover. There was none when I took it out, unless it fell to the ground un-noticed. However, the bottom right bolt hole for the bracket is larger than the others with a short step and a chamfer. The o-ring fits it nicely, but it's too thin to be proud of the timing cover surface and contact the mating surface of the bracket and too large of an I.D. to snug against the bolt. In other words, I don't see that it can seal anything.

I'm guessing the o-ring I have is for somewhere else and the bracket gets a thicker o-ring? Anybody know anything about this?

Thanks for any help!