2001 YZ426F losing coolant

My 2001 yz426f has a problem with engine coolant leaking from the weep hole under the side housing that holds the water propeller. This seems to happen only when the bike is standing still, even when it’s only a few minutes. Once it is moving again it seems to slow down or sometimes stop. I have changed the O-ring for the propeller housing and flushed the coolant but it still happens. The bike runs great and has tons of power, it starts on the first couple of kicks but I cannot stop for any length of time without shutting it off or it starts blowing out coolant.

Did you only change the O-ring? There's probably more to it. How did the impeller shaft look? The shaft could be grooved and worn out, still allowing the coolant to slip by. I changed my shaft, o-ring, and bearing and it solved my problem. Pull it back apart and check the shaft.

There are several posts regarding this issue....

Yup...water pump shaft seal/shaft are worn.

The O-ring on the cover is not at fault, the coolant side seal is, as Birdy said. The shaft may also have a groove worn in it by the seal which will prevent a new seal from taking hold properly.

Also, it should be noted that a 426 will normally force coolant out of the radiator cap over flow after about 1 minute of idling at a standstill. They don't like it, and should be kept moving, or shut down while stopped.

the only crapy part on a yamy

Did you only change the O-ring? There's probably more to it. How did the impeller shaft look? The shaft could be grooved and worn out, still allowing the coolant to slip by. I changed my shaft, o-ring, and bearing and it solved my problem. Pull it back apart and check the shaft.

There are several posts regarding this issue....

Is ther any special tools needed to replace the bearings?

a nice special common hammer...:busted:

wend removing the bearing you can hit it on the iner side, but when instaling, hit it only on the outer side off the bearing so you dont score it. if you have an old bent 22mm handlebar you can use the aluminium upper bar as a hitting tool

It s not a hard job at all I just did my 05 this past weekend,drain fluids, remove exhaust , kick start lever, clutch cover , oil filter cover and filter, water pump cover, impeller, and side cover, replace the shaft and seals, I replaced the bearing while I was in it. Parts order was around $80.00. Get both water pump seals an impeller shaft, bearing, water pump cover o-ring, side cover gasket, clutch cover gasket, and kick starter shaft seal. took about 2.5 hours to complete.

you dont need to remove the cluch cover. only the 2 bolts on the upper right side which hold it along whith the side cover

Thanks for all the information, I will give it a try!

Parts run bout 30- 40 bucks i just did mine same bike . if u freeze the new bearin it will go in a lot easyer too.:busted:

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