Serpentine belt
<hr style="color: rgb(209, 209, 225); background-color: rgb(209, 209, 225);" size="1"> I have a 1993 FordF-150. In the last 6 weeks, I have broken 4 serpentine belts. They fail like you are slicing the rear quarter inch off. The belt appears to work its way back. Everything is within limits. I put a new tensioner on and a new smog pump. All end plays are within tolerances. There is no wobble. All pulleys are free. All failures happen within 200 miles of installation. All driving speeds have been about 35 miles per hour and the truck was going straight,--no turns. I am missing something. Any ideas??

 

Check for a bur or a bent rib on a pulley. either will destroy a belt quick.

 

I had a similar problem on my '88. Come to find out my water pump bearing was loose, I don't know how I missed that.