New water pump shaft and seals leak???

4 replies to this topic
  • LBMrider27

Posted May 02, 2005 - 05:20 AM


got a 03 yz450f and put a new water pump shaft new bearing and seals and if i let the bike idle for more than like 3 minutes it leaks out of the weap hole in the bottom of the water pump anyone have any ideas or have it happen to them?? :naughty:

  • grayracer513

Posted May 02, 2005 - 06:37 AM


The first thing that comes to mind is that 3 minutes is too long to let your bike idle. Double-check, the coolant may be coming from the overflow, especially if you topped off the radiator. About a minute and a half is pretty much the max unless you face it into a good breeze and rev it up now and then.

If the leak actually is coming from the impeller shaft, there are 3 reasonable possibilities. You may have damaged the seal during installation or assembly. You may have improperly installed the seal, either failing to seat it straight, or installing it backwards. Or, and I have never heard of this on a YZF, but it happens to CRF's quite a bit, if the bearing on the right hand end of the balancer shaft is bad, the resulting wobbling motion will be transmitted to the water pump shaft and cause a leak.

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  • LBMrider27

Posted May 02, 2005 - 10:23 AM


thanks for the advice but i think it is just pressurising and is a hot spot in the system and comes out there. illl just keep er cool

  • grayracer513

Posted May 02, 2005 - 03:27 PM


The radiator overflow is in that same general area. Could be that. If your impeller shaft seal doesn't hold more than your pressure cap, you have a problem.

  • yzf450jack

Posted May 02, 2005 - 04:24 PM


You may have the seals in wrong the hollow part of the seal is on the fluid side )) ((

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