Danville and Blown330 hit it pretty good I think. The procharger that used to be on my Camaro sounded the same way at idle but, the noise went away when the rpms were raised. Another reason for the noise was that procharger used a manual tensioner on the cars. Guys who went to a spring tensioner said the noise went away. That is not the case on our trucks but, it might have something to do with the tensioner/belt tension.

Does the noise go away when you raise the rpms to 900-1100rpm?

 

I'm on my third set of idler pulleys. The first set made no noise, the one behind the bracket just wore down in a v-shape, eventually ruining the belt with it. The belt coming apart at highway speed cut through the ground cable below and ripped up the underhood heat shield The second set went out due to the c-ring breaking on the top idler, allowing the bearings to move and the pulley to walk back and forth along the unretained bearings. This made a noise similar to what you are describing. And it continued to get louder, the longer I waited to order the new idlers. As luck would play out, shredded another belt, towed it home, and ordered the idlers. The alignment of all pulleys seemed good each time, and there's not a real good way to check them. This time, however, I also replaced the stock idlers and belt tensioner assembly. Knock on wood, no more problems since.

 

I just got back and its nice to see some replies. I will check a few of the things mentioned and hopefully it is one of those so I don't have to worry about it. I do however think I need to go ahead and get new idlers and a belt. Thanks guys and keep any suggestions coming.

 

Its hard for me to tell if it goes away or not. I think it goes away, but its hard to hear over the exhaust and blower whistle. I think I may still send it in to be rebuilt. I called procharger and gave them the serial number and they said it had never been rebuilt or even called about. I was told it was rebuilt, but obviously that isn't the case. Any other comments are welcome though. Thanks guys.

 

Hey, did you ever get to the bottom of this? Inquiring minds...you know?

 

I sent it off to Procharger to be rebuilt, turns out the seals were bad in it. They replaced them and all is well now. My guess is the noise came about because it didn't have enough oil in it. When I took the head unit off, the tube running to the intercooler had oil all over it so it was definitly leaking.

 

Glad you were able to get it corrected...
Watch those idlers though...Mike @ NoLimit RaceCars in Forest Park told me they were notorious for wearing out...I can attest to that

 

When I had it rebuilt I ordered some new idlers and a new belt.