I have recently changed the idler pully on my 96 F150. I got the new pully from NAPA auto parts and after i put it on and drove around for a while, i heard some tinging coming from the radiator. turns out that the pully was positioned too far back or something and the walls )or whatever you want to call them) of the pully rubbed aginst the belt and made some pretty nice lacerations to the outside edge of the belt, it even seperated part of it (it was a goodyear gatorback). So after this i put the origional pully on and drove to NAPA to return the part (i figured the belt was in good enought shape to drive fr a little while). Then i headed over to Kregan auto parts to get a new pully and belt. The pully was not in stock so i had to wait untill the next day to get it. So i immideatly put the new belt on and drove home. The next day when i was ready to put the new idler pully from Kregan on, i opened the hood to find that the new belt that i bought (some generic brand) had been completly seperated in two by the pully. I have no idea how this could of happened because; A, it was the origional pully that had been on it for 111000 miles without a problem, and B, as far as i know, there really isnt any adjustment or washers to misalign the pully.

My question is does anyone know how this happened or how to fix it. If worst comes to worst, i can just put a washer between the pully and the radius arm to space it out better.