Need help with water pump?

Anyone have any water pump experiences they'd like to share? Just noticed I have a leak that seems to be coming from the lower back side of my water pump. It only leaks when the engine is cold. Once hot it goes away. Any help is much appreciated :cry:

Most likely leaking from the weep hole at the bottom of the engine. Time for a new water seal and impellar shaft. :cry:

Been there, done that also. Mine started leaking at about 90 miles. (only has about 130 on it now) and it did it only cold, shortly after start up and as it cooled, it dribbled a little bit more. I replaced the seal and I used special coolant that contains no silicates or borates. Silicates are know to cause premature water pump seal failures. Of course, I use the Toyotas (SLLC) super long life pink coolant (and I aint no sissy either :cry: ) as i get a real good deal on it and its premixed with distilled water at 50/50 and has none of the bad garbage in it found in other coolants. In fact, its factory rated for 90,000 miles, so it should last a year in my bike (I change it every year, weather it needs it or not) :cry:

hey i have same problem how hard is it to change out seal and impeller aslo what is best coolant to use in my bike wr400f 2000 also if i have noticed the problem awhile ago am i hurting my engine riding it since it only does it when its cold and i still have coolant in radiator and overflow?

Im into replacing water pump parts, both seals and bearing, impellar is OK

bearing was no problem to get out with heating, but what is the procedure to press it in, since heating would probably mangle the preinstalled seal

its quite a tight fit :naughty:

The little bearing just taps in cold with little effort. :naughty:

Put the bearing in the freezer for a little while, pops right in. :naughty:

On the subject of water pumps, Have any of you popped in one of those Boyesen impeller/cover kits? Are they worth what they claim to do (lower running temp, more power)? I ride in the desert frequently in 85-95 degree temps.

I didnt even think about using the pink Toyota coolant. I'm due for a coolant change - guess I'm off to the Toyota dealer :naughty:

Hi gang, I need to resurrect this thread.

I did a search on leaking water pumps and have more questions. I bought a used 04 WR450 last week. The previous owner had just changed the two seals on the water pump (oil and coolant side), but I noticed when I started it up this weekend a puddle of coolant under the weep hole. The leak stopped almost immediately upon startup. And no further drips as the engine warmed up.

Two questions.

It was below freezing when I fired the bike up. Could extremely cold weather starts contribute to the problem?

Or is it likely the impeller shaft had some damage? The guy did say he checked it thoroughly.



Extremely cold weather does make them more prone to leak.

I always replace the shaft and seal. The shaft gets a groove in it from the seal. So if you replace the seal only it will not last very long. :thumbsup:


cold weather does have its affect, but not to the poit, that new seals would leak

there are few possibilities, like: incorrectly installed seals, damaged new seals, worn impeller, bad bearing

I have to get you photos I have them

I searched to see if I could find my pics and found that if you delete the photos from photo bucket other people cannot access the any longer so here they are again!

Just replaced the seals and shaft in my 03's water pump. Indy gave me the parts list and if I would have ordered the numbers he gave me everything would have gone smooth, BUT, I didn't. Anyway I did it and if I can, anyone can.

Here are the part #'s and some photos to go along with it.

Parts to order:

#5GR-12458-00-00 SHAFT, IMPELLER

#93109-11073-00 OIL SEAL (water side seal)

#93102-12321-00 OIL SEAL (SD 12-22-5 HS)


I started by draining the coolant and taking off the header pipe

Then removed the side case.

Here is a photo of the outer water seal and impeller with the shaft already removed. The shaft just pulled out and the inner oil seal hammers out with a punch along with the bearing. The water seal popped out easy

Here is a photo of the bearing with shaft still in.

Here are the groves that everyone keeps talking about wearing into the shaft. The old one is on the left and the new one is on the right(It will be obvious)

Another of the inside of the case

Hope it helps.

I would like for someone to take a poll of what the temperature was when the pump started leaking.

Mine would only leak from about 40 degrees and below. Anything above that and it was fine.

Thanks for the info Tarfele,

I will have a look at those pictures this weekend.

It is sounding like the cold weather can contribute to and/or create the problem.

I was planning on seeing what happens in the spring when the temperatures will be warmer and hoping to see the problem disappear. But it sounds like I should address it anyway.


Dont forget that I am on my 5th shaft and seals. Experience shows that shaft grooves and seal flexibility are issues at colder temperatures. I seem to replace them every 6 months of riding. :thumbsup:

Thanks Indy WR450, I understand that you are well versed with the WR450 and I value your input on this.

The previous owner went so far as to have a dealer check the shaft for grooves and it passed inspection, so he just replaced the seals. Perhaps they aren't installed properly.

Hearing that the cold weather can contribute to the issue will help me to resist the temptation of firing it up once a week and sitting on it in the garage (too icy to take out).

I will see what happens in the spring with the warmer weather and make a point of doing the seals and shaft once per season as part of my routine prep.



cold weather does have its affect, but not to the poit, that new seals would leak

there are few possibilities, like: incorrectly installed seals, damaged new seals, worn impeller, bad bearing

What is "incorrectly installed" is it spring side towards the pressure or spring side away from pressure?

Spring side away from the pressure. :thumbsup:

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