Given that the first belt only went 18K, somethings wrong. You say it's not alignment or tension but it's obvious something is out of kilter. A belt ($175) and labor another ($175) is pretty expensive. At this point I would find a dealer or indy that can find out what is going on.

 

Two belts and the same problem indicate it's not the belt. Still under warranty? Have a dealer test-ride, duplicate the issue to them, and go from there.

Good luck.

 

Sometimes a rear rotor that is warped gives the same kind of noise.

 

Hummm, that sounds like something to check.

 

Not rear rotor noise,allready checked for that.The belt cost $180 but the tow is what realy hurt,$250 for 25 miles.I'm wondering if the engine is out of alingment.The belt is sitting in the middle of the rear pully.

 

Im pretty sure the service manual says the belt should be to the outside edge of of wheel pulley