The other day on the way to work my belt decided to come off, my belt looked a little worn so I purchased a brand new dayco belt and put it on. The jeep runs fine when idling but as soon as I apply gas the belt runs off. I checked my pulleys and they seem fine. I did this with and without the a/c to rule out the compressor. I'm at a loss for what the problem is. Has anyone had a similar issue?

 

Harmonic balancer

 

Had an idea that might be it....

 

Do a search for the exact symptoms. The rubber dries up and causes all sorts of havoc.