Wierd oil leak issue, '03 YZ450F.

5 replies to this topic
  • superretard

Posted February 19, 2010 - 06:32 PM


My new to me YZ 450 leaks oil from the bottom of the oil filter cover, at around the allen head bolt. Obviously it's not a huge leak but it's there. I HAVE replaced all o rings there and cleaned off both surfaces. The bottom bolt {all bolts for that matter} is NOT stripped and tightens down fine.

At this point I'm at a loss on what it could be. Is it possible the cover has been taken on/off so many times it's warped and not seating properly on the case?

Any ideas are welcome.

  • grayracer513

Posted February 19, 2010 - 06:47 PM


Is it a stock oil filter cover, or a slick looking black one with a big R on it?

  • superretard

Posted February 19, 2010 - 08:16 PM


It looks like a stock OEM piece.


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  • grayracer513

Posted February 20, 2010 - 06:38 PM


If it's leaking around the Allen bolt (the lower rear of the 3), it may be that the hole was previously stripped, and too short a Heli-Coil was used to repair it. This could leave the filter well drain hole partially opened to the shank of the bolt, putting high pressure oil against the otherwise unsealed bolt shank.

Try plugging the hole as described here:


I'm betting that will do it for you.

  • superretard

Posted February 21, 2010 - 06:50 PM


Hmmm, that definitively sounds like a option. So this thing is just a oil drain passage? I might try that and give it a shot. At this point a little Yamabond took care of it but I'd rather not have to do that every time I pull the filter out. Thanks.

  • grayracer513

Posted February 21, 2010 - 08:10 PM


Be certain to block the correct hole (arrow). The larger one forward is the feed passage.

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