Serpentine belt keeps coming off the pulleys
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Joined: Jun 2025
Posts: 4
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I replaced a worn belt that was slipping with a Gates belt from NAPA along with the idler shortly after I got the truck (with around 143,000 miles at the time) and it frayed and came off the pulleys after about 900 miles. The replacement belt lasted about 2700 miles before doing the same a few days ago. After a visual inspection and turning them by hand, the pulleys appear to be properly aligned and in good condition – except possibly the power steering pulley. It has about 1/16 inch of play along the shaft; I can turn it by hand, but it does not spin freely like the other pulleys.
1/16 of an inch doesn't sound like much, but could that little bit of play cause the belt to ride up over the edge of the pulley over time? If that pulley is the likely culprit, I presume the issue is worn bearings in the pump itself and not just the pulley, in which case the power steering pump would have to be replaced together with the pulley. Visit here for more details: Men's Reversible Belts. I can do the work; it doesn't look like much. I just want to be sure before buying the parts and getting my hands dirty. On the other hand, if it's not likely the PS pulley, then I'll take the truck to a local independent garage and have them check it with a laser. My eyeballs aren't calibrated as well as they used to be, so maybe one of the other pulleys is out of alignment.
1/16 of an inch doesn't sound like much, but could that little bit of play cause the belt to ride up over the edge of the pulley over time? If that pulley is the likely culprit, I presume the issue is worn bearings in the pump itself and not just the pulley, in which case the power steering pump would have to be replaced together with the pulley. Visit here for more details: Men's Reversible Belts. I can do the work; it doesn't look like much. I just want to be sure before buying the parts and getting my hands dirty. On the other hand, if it's not likely the PS pulley, then I'll take the truck to a local independent garage and have them check it with a laser. My eyeballs aren't calibrated as well as they used to be, so maybe one of the other pulleys is out of alignment.
If you're already comfortable doing the work, it’s worth a shot before taking it to a shop. But getting a professional alignment check, maybe even with a laser, wouldn't hurt—sometimes what looks straight isn't quite right, especially at that mileage. And hey, while you’re sorting out your tools, don’t forget to check out some quality Men's Reversible Belts too—you deserve gear that holds up, whether it's for your truck or your wardrobe.
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Member
Joined: Nov 2020
Posts: 36
Likes: 4
That slight 1/16" play in the power steering pulley might not seem like much, but over time, it absolutely can cause belt misalignment—especially if the pulley shifts under load. If the belt keeps fraying and slipping off even after replacing it and the idler, that play could let the belt ride up or track improperly. You're right to suspect worn bearings in the power steering pump, and if that's the case, replacing the whole pump (and pulley) is the way to go.