Motorcycle Repair: cm185 oil leak, crankcase pressure, shaft surface

Question
Bill,
I asked you awhile back on a issue about an oil leak on the counter shaft seal for a cm 185. Did as you described and replaced the seal with a new one. (ordered 3 new seals in case I screwed up) Removed the old one and found that the collar spring on the seal was broken. Put in the new one and set it to the same depth as the old seal and it still leaked. Removed that one and tried a second and the same result. I checked the shaft for wobble and wear with a micrometer and found none. I gave up and brought it to my mechanic (he has always done a great job for me) and he is having the same problem. Any suggestions?
P.S. We also thought it might be crank oil pressure problem and checked that and it was not that.

Answer
Lawrence, seals only leak when
*they are incorrectly installed,
*are trying to seal a grooved or damaged surface,
*when there is runout on the shaft
*or when there is crankcase pressure building up inside, forcing oil past the seal lips.

Did you lubricate the seal lips and shaft when you installed the seal? Is the seal sitting squarely in the case bore? Are you using a seal driver to correctly install the seal? Is there a seal lip groove in the shaft surface?

Be sure to clean out all the breather tubes, separator parts, etc in the air box and air filter, so it can provide a good flow of crankcase fumes away from the crankcase.

The shaft is cross-drilled for lubrication of the gears and shafts. Perhaps the oil hole is a little off and is near the seal lip, allowing some lubrication to pass by, somehow. Try installing the seal a little less deeply in the case, perhaps.

Bill Silver