Crank seal clearance problem

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Apr 15, 2004
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I assembled my 850 crankcases recently and things don't look quite right at the drive side crank seal. The seal sits right at the very outer end of the journal, right up against the start of the taper, and there is very little clearance between the engine sprocket key and the seal. I shimmed the crank for .010" end play, and if I push the crank over to the timing side, there is zero clearance between the key and the seal.

Are they all like that or do I have some sort of unusual problem? I was thinking I could grind the end of the key down a little, but it seems like the crank end really should project out a little further from the crankcase.

So, wondering what to do about this. I think if I ran it as-is I'd tear out the seal. :?


I just checked my spare engine and like yours, the crank seal is very close to the key slot on the crankshaft. In fact, at first glance the seal appears to be across the slot. However, the lip on the seal, which does the sealing, is pointing inward (toward the center of the engine) and is some 0.060" inboard of the key slot when the crank is pushed all the way to the timing side of the engine. I think this is fairly typical.

Is the lip on your seal across the key slot? I think if you look closely you'll find that the lip is actually riding on an uninterrupted section of the crank, which is as good as it gets, as they say.
Hi Jason,

My engine is like yours. The seal is actually just clear of the keyway and does appear to be on the journal all the way around.

Sounds like that's how they are then, so no worries I guess! :)

Still seems like grinding the key a little shorter might be a good idea.

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