GM 4.3L Serpentine Belt Squeal

"Rusty Vandura - www.tinyurl.com/keepoppo" (rustyvandura) 03/19/2018 at 13:43 • Filed to: None

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I drive a ‘97 GMC Safari with a 4.3L V6. The accessory drive belt squeals. I replace the belt and not long after, it’ll begin squealing again. The service interval on those belts is long, if I’m not mistaken, and the current belt has fewer than 10k miles on it. I’ve stayed away from belt dressing products, but I find that spraying silicone on the grooved side of the belt will buy me a few weeks of silence. A new belt is less than $30 — I always buy AC Delco Professional — and replacing it is not the biggest hassle in the world, but I just replaced it less than a year ago.

Any thoughts?

HammerheadFistpunch > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 13:57

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could be that your alternator is slightly out of alignment?

deekster_caddy > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 13:57

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Make sure you don’t have a bad tensioner pulley or water pump.

cmill189 - sans Volvo > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 13:58

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I might be completely pulling this out of my ass but I recall the 4.3, 5.0, 5.7, and maybe the 7.4 all having belt noise issues when the idler gets weak. Since they run one super long belt for everything. Maybe see if it bounces around when the engine is idling.

Future next gen S2000 owner > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 13:58

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Bad bearing in a pulley somewhere or a pulley out of alignment.

Darkbrador > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 13:59

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For what it’s worth, it may be wet, like ran full speed into a deep and large puddle ? (Don’t ask me how I’d know that ...).

Also there may be some subtle differences between engines from the same designation, such as the alternator output, which drives slightly different belt sizes. (Don’t ask me either)

Goggles Pizzano > HammerheadFistpunch 03/19/2018 at 14:04

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Dealing with this issue myself. Need new mount bushings on PS pump and AC.

TheRevanchist > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 14:05

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Speaking from my terrible recent experience that lasted a lot longer than it should have, the tensioner pulley is probably not tight enough on the new belt, or starting to go bad. Maybe/probably.

merged-5876237249235911857-hrw8uc > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 14:24

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I’ve used a bar of soap on the backside of a serp belt to help quiet it down. And it works for a while. But as others have said, the tensioner is probably weak and not keeping it all tightly running on the pulleys. I would think silicone is counter to helping the squeal. You want more grip, not less?

RacinBob > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 14:38

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I think if you will find some component (water pump, alternator or idler) to be stiff as hell and causing your problem. I once had a car that just wouldn’t keep the battery well charged. I replaced the voltage regulator, no luck.

Then one day I had the belt off off to change the fan to a flex fan and noticed it was really hard to turn the water pump. Pump changed, problem gone. It’s surprising how much drag a bad component has.

good luck.

loki03xlh > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 14:52

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Consider getting an accessory belt drive kit that replaces the belt, pulley and tensioner. I had an issue with a 5.3 that screamed nonstop. New belts and/or dressing would help for a few weeks, but that’s it. Once I replaced the pulley and tensioner, the problem went away for good.

Rusty Vandura - www.tinyurl.com/keepoppo > cmill189 - sans Volvo 03/19/2018 at 14:53

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I’d wondered about that exact thing.

Rusty Vandura - www.tinyurl.com/keepoppo > Goggles Pizzano 03/19/2018 at 14:55

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New mount bushings?

Rusty Vandura - www.tinyurl.com/keepoppo > RacinBob 03/19/2018 at 14:55

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Thanks.

Rusty Vandura - www.tinyurl.com/keepoppo > merged-5876237249235911857-hrw8uc 03/19/2018 at 14:56

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The tensioner is the easiest of the possibilities.

Rusty Vandura - www.tinyurl.com/keepoppo > loki03xlh 03/19/2018 at 14:56

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A new tensioner from AC Delco is $25. AC Delco OE is $50.

loki03xlh > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 15:02

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I bought a Gates kit from rockauto for $58. It came with tensioner, pulley, and new belt. I’m going to do the same for my S10 4.3 because it has been getting louder lately.

crowmolly > RacinBob 03/19/2018 at 16:08

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Had the same deal with an alternator. Drives you crazy.

RacinBob > crowmolly 03/19/2018 at 18:00

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Yep, its funny how the mind jumps to conclusions. Example, my car won’t charge, so I blame the alternator and voltage regulator. Never asked myself if it was turning fast enough to charge.

I suspect that 60% of replaced thermostats and voltage regulators are actually good. The get replaced just because it’s gotta be them huh. We all do it.

Goggles Pizzano > Rusty Vandura - www.tinyurl.com/keepoppo 03/19/2018 at 23:06

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Sorry for the late reply, I was pulled away. My power steering pump and AC compressor aren’t hard mounted. There are bushings. They get old and dry and after tension is applied to the belt they crush and cause alignment issues.

I googled your truck and it appears it doesn’t have them. You can scratch that one off your list. You’re welcome. :-)x Hope you find the solution!

Rusty Vandura - www.tinyurl.com/keepoppo > Goggles Pizzano 03/20/2018 at 00:12

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Several people have suggested something that I was beginning to suspect: that the tensioner isn’t as tense as it ought to be. And the suggestion also comes from my 70-something-year-old Original Gangster in Tennessee who is an absolute trove of knowledge and experience. So I’m going to replace the tensioner with an OE part and do the same with the water pump while I’m in there. As far as I know, the water pump has 100k miles on it.