Question about 2002 Yamaha YZ 426 F

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Water leak i have a 2002 yz426f and it has a water leak and is leaking out of a tiny hole under the water pump housing which i have been told is a hole from the factory as a warning for you to check whats going on. i have been told that it is a good chance that i have a buggered water seal and it needs replacing, i have looked at the manual and can't make sense of it and is the water seal the same as the oil seal or what the...... it would be much appreciated if i could get a bit of advice on this. thanx

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That water leaking is due to a head gasket pressurizing the system. That's usually one of the first signs of trouble on the horizon. The seal is not the culprit. You can check the water pump seal by draining the oil. If you have any coolant in it then you may be lucky and just have a pump seal blown in which case it is a relatively easy fix. You will need to remove the side cover and the water pump impeller to get to the seal. You can use a seal puller to get the old one out and I would use a socket or something the same size as the OUTSIDE of the new seal. DO NOT let anything hit the inside of the seal or you will kill it.
I really hate to tell you this but most often it's a head gasket leaking that causes the water problem. Is it just a drop her and there or is it pretty obvious? That makes a huge difference. If the bike gets really hot you can over pressurize the system causing the seal to weep/leak, if it drips on a regular basis then the HG needs to be replaced.

Posted on Nov 30, 2008


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