yz426 "STILL" leaking coolant after changer seals

So my 02' 426 started leaking coolant rapidly one day while it was idling after start up. Since I've been so busy, and my brother has more experience and tools to work on my bike, I told him I would pay him to do it. I bought new seals, shaft and bearing, he changed them the next day. Said he rode it around seemed fine, and then when he came home said it was leaking again.

The difference this time is that, the 1st time it leaked it was very quickly and the engine didn't have to be warmed up or running for that matter, after ripping into it and changing the seals and bearings as per the manual. Now it leaks only when it is running and has warmed up and just a slow drip. He says he did like the manual says and said that he's pretty sure that the seals where put in the correct direction, obviously we are gonna take it apart and double check, but I was hoping someone else had a similar problem and can point out a couple other things to look for to make sure its done right this time.


  • The shaft is grooved by the previous seal, and must be replaced
  • One or both seals are inserted backward (lips must face out of the bore, toward the installer, and toward the fluid they seal against
  • The bearing at the right end of the balancer shaft may be bad.

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