Water Pump Seal Replacement

Just put in a new water pump seal, after searching through the threads on this procedure. The info there was very helpful.

The impellar does unthread like a typical nut, my local dealer didn't know. I really didn't want to pull off the entire right crankcase cover, but I was concerned about snapping off something internal. But elected to give it a try. I put the bike in second gear to lock up the shaft, used a heat gun to heat up the impellor where it attached the shaft and used my impact tool working it CW the CCW and it did come off, although it resisted. There was some residue on the bearing behind the seal so I flushed it with some WD40, if antifreeze can leak out then dirt can get in. I have a needle fitting that fits into my grease gun so packed the bearing with grease. I tried seating the seal with a spark plug socket, but a socket reversed works better as the shaft will fit through a 3/8 square ratchet hole. If you do this yourself you have to pull the exhaust header to access one bolt holding the pump cover on and this is a little easier if you pull the right side radiator as well. Thanks for the help.

How were the results? I just did mine, pulling cover, replacing both seals, gasket, shaft, bearing. No issues, but would like to avoid time and $ in future if not necessary. My shaft was grooved indicating replacement?

Yeah i just torn my 04 yz450f apart today because it was leaking coolant really bad and i had to take everything a part and the impeller shaft was all groved and i just bought everything the seals bearing and shaft and hopfully it stops leaking!

Well I poured the coolant back in started it up and so far so good, but then again stuff generally doesn't break in the garage. I should have examined the shaft a bit more closely, if it was alright then I shouldn't have a problem. Does anybody know if the cooling system required bleeding of any sort. I would think with the bike on the kickstand the right side radiator is the high point of the cooling system. I may lay it on the left side for a bit just for a little insurance.

I was lucky. My bike also started leaking. I drained the fluid, took the cover off, unscrewed the impeller and pried the seal out. I cleaned the shaft with some steel wool and put the new seal back in. Tightened the impeller just ever so slightly.

Has not given me trouble in 12 hours?

I filled rad., overflow, no bleeding, no issues.

i bust a rad on my 03 450, and rode it home filling the bike from puddles with a drinks bottle i had. after changing the radiator i found i had burnt out the seal by running dry (this was only a few hours before a race meeting)

previous to this i had recently fitted a new shaft/bearing and both seals, with limited time i pulled the cover off,impellor off, pried the old outer seal out (the inner seal is lubed with oil so is usually ok)

my new shaft had grooved already, and with no ther choice i ran the bike up hold a scotchbright pad on the shaft. fitted a new seal and that was it!!! ran the bike for another year after that, then sold it

Well I poured the coolant back in started it up and so far so good, but then again stuff generally doesn't break in the garage. I should have examined the shaft a bit more closely, if it was alright then I shouldn't have a problem. Does anybody know if the cooling system required bleeding of any sort. I would think with the bike on the kickstand the right side radiator is the high point of the cooling system. I may lay it on the left side for a bit just for a little insurance.

I talked to my dealer what you do is fill the rad with about 1.27 qts of coolant and leave the rad cap off and start the bike and run it for a couple minutes while revving the bike a bit he called it "burping" the system he said it will get any air bubbles out

Silly question, I'm about to do mine on a bike thats been apart for quite some time. Can't remember the orientation of the seals- Does the outer seal have the numbers out and the inner have them in? Thanks

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