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Oil leak from behind clutch cover???

9229 Views 15 Replies 3 Participants Last post by  wynot
Came back from a hard ride on my 99' M900 and found oil leaking ot of the bottom of the clutch cover. What happened?? Did a seal let go behind the clutch? I'm pretty sure there a crank seal back there, but have never worked in that area of this bike before. Can anyone tell me what I'm looking at fixing? Would extra oil cause this? I'm about 3/4's of te way between the min and max lines on the sight glass.
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I've got it too on my 95 M900. It could be either the large seal around the outside of the "driven" primary gear where it goes through the right side crankcase cover. Or could be the smaller seal that goes between the inner surface of the driven gear and the center hub of the clutch. Oil from either source gets slung to the same place - the outside perimeter of the clutch housing.

I've been waiting on the dealer to get a right side crankcase cover gasket. The other necessary parts are all there waiting on me. When I go into mine, I'm going to replace both seals mentioned above as normal good practice. To do it right, there is also a crankcase end bush seal to replace, an oil galley o-ring, and something else I can't remember without pulling out the Haynes manual. Something like seven seals, rings and gaskets total. I'm giving up on the case cover gasket and switching to silicone sealant as many others have done.

As long as the leak isn't bad, you can keep riding. Just clean out the excess oil occasionally (don't spray solvent cleaners on the clutch release bearing) and keep an eye out that the leak doesn't get bad enough to oil the back tire or lower the oil level below minimum.

Mark J
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Yeah, thanks for the reminder on better substitutes. I'm planning on using that type of product rather than the garden variety RTV gasket makers.

Mark J
Even though it only covers through 96, the Haynes manual for 2V twins should be a good reference for a lot of stuff that just doesn't change from year to year. Just use it with caution.

That's where I worked up my parts list to phone in to the dealer.

Don't have part nos., but I'm planning on replacing:
1) Crankshaft end bush oil seal
2) Large oil seal between case cover and outside of driven gear.
3) oil seal in front inside of driven gear.
4) o-ring in oil way (very important)
5) o-ring for clutch guide (inside groove)
6) o-ring between clutch center and large thrust washer
7) Instead of case cover gasket (made of unobtanium) will use high quality gasket maker compound

Mark J
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The Haynes Manual (gotta love it!) has a bunch of tricks and tips and how-to to make tools instead of buying them.

Among those, it shows a clutch center holding tool made of two pieces of flar stock approx 24 inches long; bolted together about a third the way from one end like scissors; the short end has about 2.5 inches bent over at 90 degrees and the inside edges of those "jaws" filed to engage the grooves in the clutch center where the plates would be engaged. This tool lets you hold the center to get the big nut on or off.

Mark J

I sent you an email at the address you posted above with some part numbers.

Just keep an eye on it. As long as it's a slow weeping kind of leak and not a real drip or stream it's not a show-stopper.

I've had my bike about 14 months, and have been watching my slow oil leak from the clutch for at least 10 months.

Don't know if you saw my comments in an earlier post, but I used to use brake parts cleaner to get the mix of clutch dust and oil out every so often. Even though I tried to keep the solvent off the clutch release bearing, I thought I heard some new noises when pulling in the clutch with the engine running and the cover off. So I replaced the bearing as a precaution and quit with the spray solvents around any bearings. Now I'm just wiping the goo out before it runs out the little drain hole and down the crankcase. So far the oil is staying out of the clutch basket thanks to centrifugal force.
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