YZ125 water pump

Hello all. I recently discovered that my '99 yz125 is leaking coolant into the transmission oil. Ive been doing research and this seems like a fairly common problem and a relatively easy fix.

Ive never done this before so im wondering what exactly i will need to fix this. Ive found this water pump kit from the local shop http://www.pilgrimpowersports.com/KS-YAMAHA-WATER-PUMP-REPAIR-KIT-detail.htm?productId=10852367&ez=water%20pump%20seal which costs about 35$. Im pretty broke and looking to do this for as cheap as possible.

Looking at the yamaha motors website i priced out what i think i need for about half that. http://parts.yamaha-motor.com/partimage.gifx?d=124861,2,0,sport ...but im worried i may be leaving something out. From the yamaha site id need parts 6, 7, and 10...and i think also one big gasket for the crankcase. Is there anything else that id need? If coolant has leaked into the tranny and sat for a while will it have messed up other parts? Ive read that its possible the bearing will need to be replaced but i will not know until i pull it all apart.

I just finished doing the same thing to my 06 yz125. I think my seal went out cause I ran straight hose water and te bike sat for a month and allowed little calcium buggers to build up and eat the seal when I ran it.

You will need at the very least 6 and 7, one is the seal to keep the water from the tranny, the other is to keep the oil from the water. You might be able to reuse 10 but its pretty cheap so I would replace it. Same goes for the case cover that you will need to take off inorder to get to the WP. you really wont know what you need till you open it up and take it apart. Just check the bearing and make sure it is OK which it should be, and be sure not to bend the clip (3) all to hell. Also check the shaft of the WP where the seals ride, it should be smooth and have no groves or pitting. If you need to just clean it up with some emmry cloth, or scotch bright.

When installing make sure you have the seals going the right way, a tech manual should help with this which you can find for free on the net. Clean the area where the outside of the seal sits in the case the use a socket that is the same outside diamiter as the seal and use it to press the seal in the case.

Best case you just need 6, 7, 10, and case gasket. Worst case you need those plus WP, and bearing. I got my stuff from bikebandit and it arrived in about 3 buissness days.

PS. I wouldent worry about the water/coolent mixing with the tranny. Just flush it good and take a look at everything once you have the case cover off to make sure no rust or any obvious signs of damage.

Ah. thanks for the feedback :smirk: Will hopefully be able to pick up the new seals and gaskets next week and start ripping it apart. Its always nice to have a second opinion on something your not familiar with!

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