I know that rws just posted a thread about engine noise, but this post is a little different. When I got my 03 yz450 a few months ago I didnt hear any odd engine sounds, untill after about 25 hours of ride time. I have isolated the sound to the water pump area. At first a tapping sound was only heard at idle and was overpowered by the exaust note at throtle. It has slowly been getting louder as I have ridden it more. Now I can hear it with my helmet on and over my exaust on throttle with the dr.d pipe! I stopped ridding last weekend due to this super loud tapping. On the way back to my truck I saw people looking over thier shoulders to see if I had sheet metal baseball cards in my spokes. The bike runs great, the clutch works great, and it doesent overheat even here in Florida. My question is ;Once I pull the pump for inspection how do I know if its bad other than by trial and error? Any sugestions?