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YZ450F Water Pump Leaking

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I have been noticing some leakage of antifreeze (coolant) on my stand. After I got done with my project for the day (complete grease job), I was able to take a look at it. There is coolant coming out of the weep hole on the bottom of the water pump. I have never ran into this problem before. I work on large trucks and when this happens we just replace the whole pump assembly. I don't think that this is necessary to do to the Yamaha. I need some feedback. Do you think that it is the impeller seal, or what. I am stumped. :D:) Thanks for any help in advance.

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Your water pump seals need to be replaced. Order these parts 5be-12439-00-00 thats the cover o-ring also get 93210-19758-00 that will cure your problem. While you have the cover off check to make sure there isn't any up and down or side to side play with the impeller shaft if there is you will need to replace the shaft 5gr-12458-00-00 and bearing 93306-00105-00 you might as well change the oil seals too 93109-11073-00 and 93102-12106-00 if you decide you want a new impeller while your there 50j-12451-00-00 and the washer 90201-08512-00 thats it in a nut shell. New coolant your ready to go.

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Could you tell me what these parts are and where they go? The part numbers are great but, I need to know where they go. Thanks for the help.

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This happend to me aswell, it was because my bike was sitting for 6 months before someone bought it, and the impeller shaft sort of stuck to the seal and when it moved when I first rode it, it made a good sized groove. My impeller shaft is also wasted, and I have to wait 10 days for the stuff to come in. There goes my vacation.

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Yamaha parts break down Doug go here and you will see where they each go. This is the fische diagram that your parts guy would use to find the part numbers you need. Its pretty cool you can look up all the parts online so you know your getting the right parts. Hope that helps :)

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Dirtbikindad426,

I don't think that you looked at the problem from the correct angle. I looked up the parts that you had talked about on yamaha online (which I use religiously). I don't think that the two o-rings that you suggested are going to fix the weep hole problem. I think that it is the outer most seal (93109-11073-00). With how the case is set-up I can't see the weep hole being an issue unless there is a problem with that seal. If there was water in the oil I would need the inner oil seal and bearing (93102-12106-00 and 93306-00105-00 respectively) also. Just what I have come up with on my own. I really appreciate the input though.

Also the link that you had in your last post did not work correctly. And I work at a dealership part-time (less than 20 hrs a month). I can't afford to work there much more than that. They need me to race for them more than work.

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Doug try this (saw it work on CRF's). Take compressed air and blow air up into the the weep hole. For some odd reason it made 3 different CRF's stop leaking. It's worth a shot. Check out this post:

Leaking pump on CRF's

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I Have An 07 450f An I Have The Same Problem. I Took The Water Pump Cover Off An I See The Impeller But I Cant Get It Out. I Took The Right Crank Case Off An It Looks Like The Clutch Is There An I Get Stumped There. I Dont Know What To Do I Dont Wanna Make More Problems Then I Already Have. Please Walk Me Through It.

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Look at page 4-57 and 4-58 in your manual. In the second picture on 4-58, the flats on the inboard end of the shaft are shown. Use a 12 mm open end wrench to hold the shaft while you unscrew (counterclockwise like any normal nut) the impeller. It will be tight.

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I had this problem with my 1999 YZ400F.

I just replaced everything in the water pump (my impellor was still good). I replaced both seals, the bearing and the impellor shaft.

My thoughts are that since i was in there (with the right side crank case off) already, I might as well as replace all of it so the whole water pump was new and that I would not have to go back in there to replace parts i missed the first time i went thru the water pump.

I believe that all the parts and seals cost me a total of $60 thru the TT OEM Store...

Good luck!!!!

Patrick M.

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