my buddies got a 96 f150 with a v8, recently his belt and tensioner pulley broke off. we got the new part and put them on, but after driving it about 5 miles, the belt broke in half and seemed to have melted. we noticed that the new pulley doesnt spin freely but cant figure out how to get it too. we tried loosing it a bit but then the new belt always comes off of the alternator pully and gets wedged up on one of the pully side "rails" right after we crank the engine over. has anyone had this problem or know how to fix it?

 

Sounds like the tensioner pulley is seized and melting the belt. I was always told that if the tensioner goes out, buy the whole thing and not just the pulley wheel itself. Also, keep in mind that the pulleys that spin clockwise have a bolt that comes out counter-clockwise (or opposite thread) and vise versa

 

sounds like you need a new tensioner.