Coolant leak / impeller shaft

3 replies to this topic
  • Jneum

Posted June 28, 2000 - 08:54 PM


I have developed a coolant leak from a small hole in the right side case that is just below the water pump impeller housing. Is this caused from a bad seal or something more serious. The hole looks like a factory one however a steady stream is coming out. There is no decay of the metal as I once had with a Honda CR. The side case metal appears to be in great shape.

Additionally I have a question about the removal process for seperating the impeller from its shaft. Can the impeller just be loosened w/o removing the side case or has Yamaha designed it so that the side case must be removed and then while holding on to the shaft from the back side, the impeller can be loosened with a socket.

Any help in this matter will be greatly appreciated since I have never had the side case off.


  • MotoGreg

Posted June 28, 2000 - 09:32 PM


You'll need to get the two impeller shaft seals and clean the shaft with fine sandpaper. You have to remove the whole side cover which includes removing the clutch basket, kick starter, ect... When you remove the water pump loosen the impeller blade with a 12mm socket, it has regular direction threads (counterclockwise to loosen) and then when you pull off the cover you can spin it off by hand.

'99 WR400
'92 GSXR 7/11
Visit my photo album AT YOUR OWN RISK!! My photo album
Anyone here a sportbike fan also? Then visit us here at

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • RodH

Posted June 29, 2000 - 12:53 PM


Is it a 98 model ? There was a problem on them, and it is advised by Yamaha to replace it with a 99 water pump. They improved them from 99 onwards.

RodH Canberra, Australia<A HREF="" TARGET=_blank>
400 Thumpers Australia</A>
2000 WR400F See Photo's and Modifications

  • Jneum

Posted June 29, 2000 - 02:07 PM


Yes it is a '98 model. When you suggest that the water pump should be replace with a '99 model year or newer, just exactly which parts are you referring to?


[This message has been edited by Jneum (edited 06-29-2000).]


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.