This is on a 1993 F150 4.9. A few weeks ago my serpentine belt shredded while on the highway. Considering its age, I just replaced it. A few days later same thing. Bad belt? Try another. Another shredded belt. Put on a new one and sat there watching it idle for a while. Perhaps after an hour or more the belt rode up on the back edge of the power steering pump pulley. Found a cracked edge lip on the tensioner pulley and changed that. OK for a few days but then it ate another belt. Watching again, after some time idling, the belt slips a rib and rolls up onto the back edge of the power steering pump pulley. I notice that even before the belt rolls over the edge of the pulley, it is riding right against the back rim of the tensioner pulley.
Here is what I have considered:
1) The tensioner itself is out of alignment and aiming the belt to the back side of the power steering pump.
2) There is end play in the power steering pump that is letting the pulley "shoot forward" and having the belt ride up on the back edge.
How does one check the alignment of the pulleys? It is either an alignment issue or something I've not thought of. Any thoughts? Thanks in advance!
Joe

 

After some checking pulley alignment with a straight edge, I concluded that the tensioner pulley was cocked at an angle. Pulled the tensioner off to find that it was cracked down the back from top to bottom through the center line. Likely when the first belt went and was grabbed by the fan, etc. the tensioner was pulled harder than it could resist and broke in such a way that I could not see it without removing it. So far so good. The belt rides in the middle of the tensioner pulley and after some driving around it has not hopped grooves.

 

Good follow up, update skills... Im sure even the two posts here may help someone down the road.... Wish more people would take the time to post back even if no one had a answer for them...

 

My good friend had the exact same thing happen on his 4.9 about a year ago.

 

I agree, great feedback. Whenever you start having belt failures when the belt is not that old and/or multiple failures it's time to look at the tensioner and pulley. Excellent find!

 

I agree, it would be a big help to others with the same problem if more people did this!

 

I've learned on his forum and the one for Explorers that communicating what was the root cause or what was needed to do a repair is important. Advice is good and appreciated but learning what works seals the deal.
Joe