Recently had to replace the tensioner in this truck as the pin on the back that keeps it from torqing broke off. Once I replaced it, the belt refused to stay on the pulleys. As soon as the ignition is turned, the belt I just spent 5 minutes looping over the pulleys gets pulled off the end of the fan pulley in the center of the assembly.
I guess one or more of the pulleys is misaligned, but how the heck? All I changed was the tensioner.
If the tensioner was the only thing changed, logic should tell you there's an issue with the tensioner.....misaligned, incorrectly installed, faulty part or wrong part.
There was a diagram with the belt (got a new belt as well as new tensioner), as well as one on a sticker right underneath the hood, which I've followed exactly, and I've tried putting this belt on at least a dozen times, so I've had plenty of opportunity to double check. And I thought about the tensioner, but there's only so many ways it goes on, what with the anti-torque pin that slips into the hole on the brace you attach it to. The tensioner pulley is just a wheel, too, with no grooves or lips. If the tensioner was misaligned, the belt would slip off of it first before all the other pulled with v-grooves and lips, right? Instead, it's always the pulley in the center that drives the radiator fan that it jumps off of first, every time.
Is there some trick to serpentine belts that I don't know? I've changed the alternator on this truck in the past and put it back on without problems, but for the life of me I can't get it right this time.
Is there an idler pulley as well? If that is bad, it could be throwing off the geometry. Are the rotating devices rotating? Alternator, water pump, smog pump, power steering?
The new belt....is it the correct one? My techs always want to use a slightly longer belt (they're too lazy and won't pull the tensioner over far enough.
The new tensioner.....is it the proper one? Can't trust every parts man. They make mistakes as well.
Hmmm...there's an indexing mark on the tensioner assembly. Make sure it's lined up....double check the number of grooves and belt length on the new serpentine.
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