hey guys just thought i would give you an update on my 04 crf 450 water pump problem. I had the same problem with coolant leaking out of my check hole. I replaced the water pump seal and drilled a 1/8" hole in my impeller just like the 06 crf 450 does. I now have about 16 hours on it and no leaks noted at this time. Hope this helps.
hey just replaced my water pump seal $5.00 and i also drilled a 1/8 hole in the impeller just like the new design on the 06 crf 450. I have about 5 hours on it and no leaks yet. it is reall easy to do, just take off the impeller cover and drain all the coolant, you need a 10mm socket to take the impeller off, stick something through the back spokes so it wont spin and use a couple of picks to get the old seal off. then use a socket to put the new seal back on.