# Squealing alternator belt



## Roqetman (Aug 31, 2015)

I have tried several types of belts but still get that awful squealing noise at high rpm from the alternator belt. I’ve tried the solid V belts and the notched V belts. I tried retightening the belts only for them to start squealing again. The same belt runs the alternator and power steering pump. I usually buy Gates belts. Does anyone have a solution for the brand and type belt I should use? Thanks!


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## Sick467 (Oct 29, 2019)

If one of your v-groove pullies has worn beyond it's use...the belt may be riding down too far in the groove and riding on the inner diameter of the pulley. They like riding on the "V" side portions, not on the inner dimeter of the pulley. Check how your belt is riding in the pulley. If the outer diameter of the belt is getting flush (or below) to the outside diameter of the pulley, it may be time for a new pulley. It's hard to say high far flush or below is "not good", but if the ID of the pulley is shiny...there's a good sign that the pulley has had it. The sides of the "V" should be shiny, but not at the very bottom.

You may have something starting to seize-up too. Hard to turn accessories will squeal the belt.


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## Roqetman (Aug 31, 2015)

I had changed the alternator and the v belt was protruding a little above the pulley and was squealing, so I changed pulley to one where the belt rides even with the top of the pulley, still squeals. I’ll check to see if belt is too deep in the pulley. Thanks!


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## PontiacJim (Dec 29, 2012)

Roqetman said:


> I had changed the alternator and the v belt was protruding a little above the pulley and was squealing, so I changed pulley to one where the belt rides even with the top of the pulley, still squeals. I’ll check to see if belt is too deep in the pulley. Thanks!


You tried the Dayco brand Top Cog belts and they did not work?

Many belts are metric in size and do not have the correct pitch on the belt to ride correctly on the pulley.

Could also be the fan is pulling a lot of air since you said high RPM. Are you using a clutch fan? Might help over a solid hub fan as it'll slip at higher RPM's.

Also, don't know if your brackets and their positions are as factory. It could be possible to mix/match stuff that works, but does not allow the belt to cover a large enough surface/radius on the pulley to get a good grip - so it can slide rather than pull. One reason you see idler pulleys on modern cars - they can make the belt contact a greater area on the pulley so they don't slip.


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## lust4speed (Jul 5, 2019)

Gates is my personal choice after going through many different brands. Most belts act like big rubber bands and continue to stretch while the Gates is like hitting a wall when tightening it up. We have both the 1965 2+2 and the 1965 Catalina Safari engines that share the same setup as your engine with the one belt doing double duty, but neither engine belt squeals. So one belt can successfully run the water pump, alternator, and power steering. We also run the Hayden 2797 Severe Duty fan clutches and still no squealing. Here's a photo of the initial engine installation in the wagon.









This kind of brings you down to alignment like Jim mentioned above or insufficient belt tension. I might also mention that once a belt slips and heats up it can glaze over and squeal that much easier after that. Pulleys can also become super smooth if the belt has slipped and it might be worth it to roughen up the pulley contact surfaces. Best to do this with the belt off and engine shut down. It's very tempting to let the engine rotation help out with the sanding, but all too easy to end up with fingers taken off.


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## Roqetman (Aug 31, 2015)

Thanks guys, you bring up some interesting points about something that I thought was a simple V belt. I will check for alignment and fit of belt in the pulleys. I normally prefer Gates but will also try Dayco. Stretch with the Gates notched belt has been a problem as I have had to tighten the belt a good bit since new. Would a solid belt be less likely to stretch or squeal??? My car has the factory clutch fan w/7blades, original brackets and pulleys. When i say high rpm, the squealing starts at 4000 rpm, which I’ve come to use as a shift point for the TH400. But I want to get to 5000 rpm without that awful squealing… of course I don’t want to hear that other awful noise either, the go that goes… BAM-Bam-bam…!


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## geeteeohguy (Feb 2, 2008)

Alignment is critical, as is proper size and pitch of the belt, as stated. Also, rubber products made in the past 15 years are vastly inferior to the original products due to green climate change agenda.


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## Roqetman (Aug 31, 2015)

Hey Guys, I wanted to update you all that the squealing alternator belt, it has been solved thanks to your expert advice. I checked the alignment and determined it was slightly off. So I removed the alt pulley and de-glazed it with a Drexel tool and added 2 washers behind the pulley, about 1/8”, and the squeal is now gone! Before, it was squealing at 4000 rpm, now she runs up to 5500 with no squeal. I swear it seems like the engine even runs better now. I’m reusing the same Dayco notched belt that was squealing with no problems. In the past I have had a couple different mechanics try to solve the squeal to no avail. So I am very pleased to have this noise gone! Thanks again for the advice.


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## geeteeohguy (Feb 2, 2008)

Thanks for the update. Accessories like water pumps and alternators and steering pumps are much happier without the side load of an out of line belt, too!


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## redhotgto66 (Sep 11, 2021)

yup just solved my squeaky belts the same way, used a washer behind one side of the power steering pump and the squeal went away !


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