O.K. Here's the story. Got up this morning and started my '96 6cyl. w/ air. and the main (and only) belt shredded. Took the wife's truck to auto zone, picked up a new belt and replaced it. No problem so far. I DID notice when we were putting on the new belt, the very bottom pulley (I believe the one attached to the crankshaft) seemed out of alignment with the other pulleys.
It looked about 1/2 inch too far forward. Didn't think too much of it at the time. I ran some errands and everything went fine.
A couple of hours later I got in the truck to go grab lunch and the back of the fan blade is hitting the front of the pulley. (barely, but making a heck of a lot of noise) Upon further insp.
I realized the belt had offset one groove on the aforementioned pulley. (the crankshaft one) Now, I don't believe my CRANKSHAFT has moved, but is there another bolt that may have to be tighened to push this pulley back into alignment? Have you had or heard of this problem? Is so, How should I go about fixing it?

Any input would be helpful. T.I.A.

 

I had a similar problem about a year ago, found out my crank pulley was cracked and no longer straight, replaced it and the harmonic balancer just to be safe, no more trouble after that. Mine was not bad enough to cause the belt to touch the back of the fan blade though.

 

That's Input! Thanks.

 

The balencer is coming apart. There about 100 bucks.

 

Thanks to all that replied! (both of you ) I recently bought my '96 150 used and am not that familiar with the vehicle. Thanks for responding to a Newbie.