I have a 2003 Xterra 3.3L non-S/C. Its got a funny whine. Its a low hum when idle, then turns to a whine when you rev the motor. I already took it apart once thinking it was the timing belt, I re-adjusted it, no change. So I'm pretty sure its the water pump but would like to make sure befor I repleace it.

So from my understanding the water pump runs off the same pulley/belt as the fan. So if I take off the belt and start it, and the whine is still there, then its not the water pump correct?

Then it could be any of the other pulley's, which I would check in the same way. Then my last hope is the timing belt tensioner.

Any input on this would be greatly apreciated. Thank you