I have a 01 xj sport that has been sitting for about 2 months. I go to fire it up lots of squealing, smoke then the belt pops. The belt was vary old. I could spin all the pulleys but the alternator. I'm guessing the alternator is locked up. Has anyone had a alternator lock up?

Personally, I've never had one lock up, but the pulley on my last one sheared off of the stud or whatever it's mounted to. Had to get a new alternator, belt and idler pulley

I've had one seize before. The bearings got so hot the pulley glowed red and it actually melted the belt. Had to drive it home with several 'cool off stops' as the water pump is also belt driven. I found a new one at a local alternator/starter shop (rebuilt) for about 1/2 the cost of a new one.

I should be able to turn the pulley by hand right?

yes... you should be able to turn any of your pulleys by hand with ease... you sir have a seized alternator.. remove and replace..

Just out of curiosity, but where did you get your alternator from? The cheapest rebuilt ones I've seen recently are just a little less then a new one.

With the OP having the 2001 "0331 head", I suggest he doesn't try this to avoid the risk to running hot...if he was considering driving it...

I have the 01 with the bad head which is why its been parked for a few months. A kid hit it trying to go up a snow covered hill next to my house. Hit my trailer and jeep so now I have to get a estimate done

The exact same thing happened to me when my alternator seized.

Mine locked up about five years ago. Took it to a local auto electrical shop for rebuild -- ~$45.00.