Leaking waterpump


on my wr426 the water pump is leaking out of the tell tell hole, is there just a seal i can get or do i have to buy a whole new pump?

also is the timing chain tensioner auto or have to do it manualy.


Often just the seals can be replaced, you need to take it apart and inspect it though (see my short writeup on WR400F water pump rebuild in this section).

Cam chain tension adjustment is done automatically.

new seal is all you need unless your shaft has some wear - inspect for any wear on shaft, if so, replace.

if your concerned about your tensioner, why did something go wrong??


i just bought a seal for £3 ish from my yamaha dealer they suggested to just put that in , only gotta take the water pump cover off not the whole case cover to do the job , should be easy , doing it tomorrow


I took off the front pipe , drained the coolant by the bottom bolt that holds the water pump cover on , took off the water pump cover , took off the impeller , pulled out the old seal , put in new , replaced cover and front pipe etc , filled just the rads with fluid and JOB DONE in 20mins, piece of piss ! btw i'm a coward usually but this was easy .

Yea I know i should of replaced loads of other bits but it aint leakin and i'm happy for now :thumbsup:

edit again, still leaks a little , gotta do the job proper now :rolleyes:

edit yet again !! : sorted it now , i had put the seal in the wrong way round as did the last person !

put the seal in with the hollow not flat face towards you .

I just cranked mine today and at first I thought it was leaking gas or something. Traced it down and at first I couldn't tell where it was coming from but got down all the way and saw it. Heading to the dealer tomorrow

ok, just changed my seal and is still leaking out of the hole. I did not take the impeller off or shaft. If those are bad could that be the cause of the leaking still??


How do you figure you did not take the impellar off? The seal is under the impellar. You must first clean the water pump area, then remove the bottom drain plug and drain the coolant and dispose of the fluid, then remove other bolts of pump cover, then remove cap on crank case (crank cover cap so you can hold crank with a CLEAN socket while loosening impellar on pump side of bike) then loosen impellar, then use pick or small pliers and small screw driver to remove seal. Inspect shaft and if there is significant wear then replace the shaft too (much bigger job). If not, then grease the snott out of the seal and shaft and then reinstall carefully and press it in firmly with old seal and socket and hammer. reinstall impellar and covers both sides with a torque wrench (I use locktite on all bolts). I always take bike out to streat and leave the drail plug out and fill radiator with water and leave hose on a bit while you start your bike and then flush the system taking care not to use too little water. Once complete (dont forget overflow tank) I put new fresh coolant in. These WR's run hot so I would consider Engine Ice. Good luck, Jason

I had my 03 wr 450 leak out the weap hole as well, it was the day of a big weekend of riding so i found a place that had the seal but they said i should replace the shaft and bearing as well, at the time they did not have the parts and i did not have the time, it has not leaked agian but over the winter i decied to order the shaft and bearing. i tore it down but now see i have to pull the case off to replaced the bearing and seal, i dont see and wear on the shaft but do have alittle up and down play in it, is that normal? should i tear it down and replace it or just hold on to the parts and do it at a later date if it fails?

I've finally sorted mine now , I had the seal in the wrong way round .

Have the hollow part of the seal facing You when you put it in and also some waterproof grease :thumbsup:

how do you pull the seal out?????

with your teeth - just kidding! A very small flat screw driver and pry it out a little at a time in a circular motion. If you use a needle nose with it at the same time it slides out pretty easy. Dont mess it up cuz you can use it to install your new one by hitting on it instead of the new one. Jason (use grease)

any pics of the weap hole ?

i have looked on my 08 WR but not sure where i supposed to be looking.

i know on cars were the weap hole is usally :thumbsup:




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