Ford eating serpentine belt

[BamaFan]

My son has an 88 F-150 that has started shredding belts. I've checked out all the pulleys, alignment, etc. and the only thing I've found that is suspect is the power steering pump. The pulley on that has a little in/out play (maybe 1/8 inch). Is that enough to cause the belt to get out of alignment and get shredded? Any other suggestions what's causing it? Tensioner pulley seems fine, btw.

 

[Rivershot]

Idler and tensioner pulleys can feel and spin fine, until they get hot, then they can lockup.

I would replace both first, usually its a good idea to do it when you just replace a worn belt.

 

[poopdaddy]

that must be a BIG serpentine belt..

 

[whitmo]

Have you checked the harmonic balancer for wobbling? Sometimes the rubber bushing they are mounted with starts to slide out, crack or crumble. Could get bad enough at higher rpms to damage the belt.

 

[gh1950]

that must be a BIG serpentine belt..

It is.

Had a F150 of that vintage. Never shredded a belt because I changed them regularly.

May be stating the obvious, but make sure you get the correct belt. Should have the ribs on the inside.

I don't know the technical term but the cross section has to be the right shape.