ISO of belt tension pulley WITH shoulders...

[The Munz]

Wind driven rain permeated the engine compartment resulting in a wet belt and pulleys. Parked and cold, upon initial start-up, the belt slips, releases tension and walks off the tension pulley and wraps around the crank pulley. It's only happened twice, but the second time the belt was damaged. Question: Any recommendations/feedback on what brand of 'shouldered' tension pulley to purchase/ NOT purchase etc?
'94 6.5 K2500.
Thank You!

PS. I realize a shouldered pulley may chaff belt edge over time vs. flat pulley, but spitting a belt off and rendering it useless is worth the risk.

[Robyn]

Take a look at the later style flanged tensioner pulley for the burbs. (1996 or so)
These have a flange...
They are meant to run on the grooved side of the belt....but may solve the issue....

[DmaxMaverick]

If a belt is slipping off a pulley, even wet, something isn't aligned, is wore out, or the belt isn't routed properly. A "shouldered" pulley won't correct that, and may lead to a more serious failure. The belt should not lose tension or walk off a pulley because it gets wet. It may slip some under load after a cold start (alternator load or cold bearing seals/grease), but it shouldn't lose tension. If it's slipping or chirping/squealing, for any reason, the belt is used up or damaged (or poor quality), or the tensioner isn't tensioning properly. The tensioner can have a broken spring and still "feel" OK. A failing accessory can cause the belt to fail or come off, so check each and the tensioner/idler(s) for a smooth, silent turn with the belt off. If any of them are noisy, you can feel them turn, or they spin too easy, a bearing is shot. If a belt slips off a pulley while running, even once, it's likely damaged and will never be right.

[JohnC]

Make sure it's the right (length) belt, too.

[The Munz]

Thank You.

[The Munz]

Very thorough info. Thanks!

[The Munz]

Yes, belt length is correct. Thank You.

[JohnC]

Yes, belt length is correct. Thank You.

I guess what I'm saying is, make sure nothing has been changed that would affect the belt length, like installing the alternator from a gas engine, which uses a different size pulley...

I recall there are marks on the tensioner that will tell you if the belt length is correct.