Oil Leak from Left Crankcase Cover

6182 Views 6 Replies 3 Participants Last post by TOE, Apr 20, 2015

TOE

Discussion Starter · Apr 18, 2015

A few months ago I got my first motorcycle, a 1980 CM200T. It ran fine for a little while, then one morning when I got it running, it started leaking oil, fairly heavily, from the left crankcase cover. I figured the gasket blew and all I needed to do was replace it, but after doing that it was still leaking. I noticed there was this little machined grove in bottom of the crankcase cover:

Auto part Engine Machine Automotive engine part

It seems like theres a specific part that would fit in that slot, but after searching all over the place I couldnt find anything. Someone posted this same issue somewhere else and the only person to respond told him to fill the space with liquid gasket. Before i do that i wanted to check here to see if anyone with the same bike could shed some light on what this mystery groove is. Like i said, this is my first bike, so i don't know much of anything and any help is greatly appreciated.

Thanks!

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J-T

· #2 · Apr 19, 2015

Not familiar with your bike but that looks to me like a drain hole, probably to release any oil that gets past a leaking crankshaft seal.

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TOE

Discussion Starter · #3 · Apr 19, 2015

Thanks for the quick response! So there shouldn't be any oil getting in that area in the first place and that hole is just there to let small amounts out? Does it seem weird to you that there is a gasket that lays over that? Another weird thing, if it is a drain hole, is that it drains the oil right over the exhaust, which seems like it could get sketchy.

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66Sprint

· #4 · Apr 19, 2015 (Edited)

There IS oil within the case, but THEORETICALLY, the case is half dry and half "wet" and the oil is kept/stays in the inner half (where the starter clutch is)......
Because the outer "half" contains the points, that drain is there to prevent the oil or moisture from building up deep enough to affect them......
KEEP THE DRAIN OPEN.....
IF you are getting a lot of oil drops out, it is likely your oil level in the engine is too high to begin with......
This can be from overfilling (while the bike is on the side-stand instead of the main stand), or from the oil being thinned and increased by fuel getting into it....
Neither circumstance is desirable, but the latter can destroy the engine rather quickly.....

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TOE

Discussion Starter · #5 · Apr 20, 2015

Yikes. I was completely out of oil so i added 2 quarts, like the manual says, so i don't think i overfilled. How would fuel be getting in there and how can i prevent it? I don't want to ruin the engine. I'm thinking about taking it into a mechanic just to play it safe, but if there is an easy fix that'd be sweet too. Thanks for the response man!

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66Sprint

· #6 · Apr 20, 2015

So....You DRAINED the oil COMPLETELY and then added the correct amount?
OR you didn't see any oil on the dipstick and added 2 quarts?... MAJOR difference here.....

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TOE

Discussion Starter · #7 · Apr 20, 2015

Yeah, sorry for not specifying. I did drain the oil completely before adding the 2 quarts.

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