'82 R100: Strange Leak Behind Front Cover

George Koch · 2020-07-04T00:38:17Z

This is the strangest oil leak I've ever seen. 1982 R100, 42K miles. Last winter I did a fairly extensive replacement of seals and gaskets to fix numerous oil leaks, most of which were simply due to PO neglect and the obvious 38 years of life. I pulled both cylinders and replaced all gaskets and seals and cleaned everything up. I pulled the front cover, alternator, and bean can and replaced all seals and gaskets, as well as upgrading the alternator to the Omega 600 watt unit. I've run it about 600 miles since this work (lots of other stuff, too, like carb rebuilds and fixing leaks on the final drive and transmission) and it runs superbly, with no leaks . . . Other than this one: I'm seeing a leak that shows up at the bottom of the front cover. Pulled the front cover and I see that the leak emanates from one of the little round nuts (Allen key used to tighten) that holds the inner cover to the engine. FWIW, it's the one on the right side of the bike. So, to be clear, the inner cover is held to the engine by a number of socket head cap screws, but in two places there are little 6 mm studs sticking out from the engine and two of these round nuts (Allen key used to tighten) are used on these. WTH? I cannot tell from the parts microfiche (MAX BMW) whether a wave washer is supposed to be used under this nut; none was present when I disassembled it, but I know someone was there before me. I added a wave washer, but that made no difference. I am about to install an o-ring that fits tightly over the stud, then install a wave washer and the nut. But obviously that's not OEM, and it didn't leak when it was built. I didn't leave anything out when I put it together, like the two little spacer gaskets that go above the main gasket between the inner cover and the engine. Any suggestions?

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My Airhead Needs Help

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George Koch

(@2752)

Posts: 15

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Topic starter

Couple more hot (over 90°F) rides since then, and no leak. You've taught me a new technique for fixing odd leaks!

Posted : 07/20/2020 17:44

Richard W

(@wobbly)

Posts: 2631

Member

Glad to help.

Realize that at 40 years of age, the oil seals and o-rings are all getting hard and becoming less resilient. So not all your leaks are going to be that easy, cheap or fast to repair !!

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

Posted : 07/21/2020 21:36

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