I tried to start my 01 XJ this morning and it was very slow to start, you could tell it was really struggling but after cranking for 3 or 4 seconds the engine started. But once it started I heard the loud screeching coming from the belt that I'd heard a few times before (my alternator went bad a few months ago so I'd heard this a lot, as well as my AC compressor dying recently). But this is probably the loudest I've heard it and unlike previous times, it doesn't go away. I only left it going for a few seconds before I decided it wasn't going to go away, and when I checked under the hood there was a lot of smoke coming from the belt--looks like it's coming from the pulley at the crankshaft. Any ideas of what to do?

 

hopefully its a worn out belt. take it off and spin each pulley and check it for loosness or drag. if all pulleys check out, then try tightening the belt a bit. should be like a 1/2 inch of play in it...