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?
Only thing I know is the oil seal behind the alternator and then the o-ring where the crank shows through.
It's very easy to pinch that o-ring !
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
I'm having trouble finding which o-ring you mean. Only o-ring I can find on the fiche is the one at the rear of the crankshaft. Just a bearing at the front.
You don't mean the o-ring on the bean can?
Everything is dry behind the front cover except the area below the stud/nut I mentioned above.
You don't mean the o-ring on the bean can?
Yes, guess so. Sorry, working from memory and not from the fiche.
Everything is dry behind the front cover except the area below the stud/nut I mentioned above.
A photo would help.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Going out to the garage with a camera now. Should have a photo within an hour or so. Thanks!
Took a couple of photos. One is just an overview with the front cover removed. The leak emanates from the round nut at the top of the cavity shown at the left side of the photo (right side of the bike). This is the nut that goes on the 6 mm stud from the engine block; this stud goes through the top hole at that side of the big gasket sealing the big black (removable) casting at the front of the engine to the engine block.The other is just a closeup of the cavity.
I guess I don't know how to insert photos in this forum. I'll try again.
OK, one photo is obviously an overview with the front cover removed and the other a closeup of the problem area. The leak emanates from the round nut on the 6 mm stud that is at the top of the cavity in the black casting shown at the left side of the photos (right side of the bike). This stud goes through the big gasket between the black casting and the engine block and is at the top of this gasket.
Ahh, your photos made it very clear. Thank you.
You have 1 of 2 issues, neither of which is worth any major disassembly. Either the inner cover gasket is torn at the stud, or the stud hole itself is not a blind hole. Either way, oil is simply wicking its way along the stud. It happens.
Pull the fancy nut and wave washer. Thoroughly clean the area with aerosol brake cleaner or carb cleaner. Blow that off or allow it to dry. Find a standard flat washer that will fit the area. Clean the washer and the fancy nut. Coat both sides of the flat washer with LocTite Gasket Maker #518. HERE
Slide the flat washer over the stud. Then apply the same sealer to the threads of the stud and install the fancy nut. That will not stop the source, but it will stop the external evidence of the leak. The leak will then become internal to the engine itself and cause no harm.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks for that quick response. I did something along those lines, but your solution undoubtedly will be more effective. What I did was to slip a tight-fitting o-ring down the stud, then place a flat washer on top of it, then snug down the nut on the flat washer, squashing the o-ring in an effort to stop the leak. Of course I did a surgical clean of everything first with Brakleen and compressed air.
I'll take it out for 70 miles or so in the heat tomorrow and see what happens. If/when it doesn't work, I'll do it your way.
O-rings work great in a "loose" install, like using them on the handle of the engine oil dip stick. In that instance, your hand judges the compression and knows when to stop. However, in a torqued installation, they usually require an "o-ring groove" which gives them a set, maximum compression distance. So while your solution is inventive, if the o-ring is cut, nicked or gouged it can all "go south".
Order the 518 as a backup. It does not require pristine, oil-free surfaces to make an excellent, absolutely oil-tight seal. Wiped down with a shop rag is generally clean enough. Even if your fix works, you'll use it up on oil drain plugs and sealing fork leg bottoms. Once you experience it, you'll judge it absolutely indispensable.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
You were of course correct; my o-ring approach was a miserable failure. The o-ring was squashed by the washer and then relaxed, thus rendering all of it pointless as the nut no longer was under any torque whatever.
So this afternoon I followed your advice, cleaned everything quite scrupulously, and used the anaerobic sealant I have on hand (which I think is very similar to your recommendation; it is Permatex 51813, Anaerobic Gasket Maker), smeared on the stud threads, on the female threads of the nut, and on both sides of a flat washer. Snugged the nut reasonably tight and put the front cover back on.
I'll report results after I run it 70 miles or so.
That's a great fix !
LocTite is the brand name of the Commercial and Industrial product line, while Permatex is the same product line for Home Garage use. It's most likely the very same product packaged 2 different ways. Since the number contains "518" that may conform my suspicions.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
I am cautiously optimistic that this fix has worked; today I ran it about 80 miles in hot weather, and do not see external evidence of an oil leak on the front cover (as I had before).
Thank you for a new approach that would not have occurred to me, even though I had the proper materials in hand all along!
As is often the case, one party is merely standing too close to the forest to see the trees.
Glad to be of help.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Advertisement
