I'll tell you what. Pop you hood..and use the throttel control on the throttle body to listen from under the hood. If you hear it clearly there, get a fiend to help you. Get a broom sitck, thats made out of wood, and ithout the broom. Have your buddy rev the engine to where it makes the noise, and hold it there. You will use the broom stick the touch various parts of the engine, i.e. water pump, alternator etc. Place the stick on your head, like behind you ear while the other end is on the accsory you are checking. I know it sounds funny, but it works, the wood actually tramsmits the sound (and vibration) to your head, which you will hear clear as day when you find the part the is making the noise. I suggest starting at the front because, with a new belt tensioner and water pump, it is possible that there are loads on something that wasnt replaced adn should have been, or what ever, causing the earing to start singing, letting you know that its time to replace them(or accessory). I can describe more clearly if you want...BY THE WAY...be carefull where you put the stick, you know, hte other end will be around your head, dont let it hit a pully, or something, because, let me tell you, it will hurt. Hope this helps....

Chase

I know this doesnt sound to inteligent, but carefully done, is very effective at finding noises..Ever heard of a mechanics stethascope?....