Help w/water pump: how much radial play is normal?


Jun 5, 2000
If you hold the water pump impeller in your fingers and move it up and down, how much radial play is normal? I've never had any problem with the water pump, but now I'm wondering. Is some play normal on a KDX? There seems to be a spring or something in the mechanical seal, you and feel it if you push axially. This all got started when I got my copy of Eric Gorr's book in the mail yesterday (which is great, by the way) and read the part about checking over a used dirt bike where he says any radial play in the pump is a bad thing. Since my side cover is off for other reasons, I decided to check it. I estimate I'm seeing about 1/32 inch (~0.03in) of radial play, maybe a tad less. Looking at the schematic in the shop manual, it looks like some flex would be expected since the impeller is way on the other end of the shaft from the bearing, without any support other than the seals - on the other hand, E. Gorr knows more about dirtbikes than I do. Is this a case of "a little knowledge is a dangerous thing" :D or do I have a problem?



96 KDX 200


Mod Ban
Dec 10, 2000
I deon't think you have anything to worry about. The shaft in my bike has a slight amount of radial play, and the seals don't leak.

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