Terrible belt squeak

[Zach]

Howdy, I replaced my two belts, power steering and alternator there is no A/C just wraps around the dampener and water pump. They were in pretty rough shape and it would occasionally squeak. I used masterpro #7480 and #7508 since that is what were on it originally, so I’m unsure if it is correct since we didn’t put the originals on. They fit nicely and I tightened them down as good as I could, still some play if you twist it but you can’t move them up or down. Never changed belts before so I was just doing it  how it was. Now they squeak significantly worse during pretty much any moderate rev or more can easily be heard in the driver seat. Curious what kinda steps I could take. Different belt? Tighter? Looser? Thanks.

[Wallington]

Sometimes new belts can squeak at first until they bed in, likewise if pulleys freshly painted or powdercoated until the surface wears. But generally a squeak or squeal is from belt slipping just enough to move. Nip them up a tad tighter, inspect the belts and pulleys to see any new wear or patterns that didn't match previous. Under load will make it worse, turning AC on, power steering at close to full-lock, revving the engine, anything like that will squeal more when done. If just contact make sure the belt size and type is correct, not out of alignment or pulley order.

[FormTA]

Belt squeal is annoying. I've been chasing it on my daughters 03 lexus and it has serpentine belts with manual tensioners.  I really feel it is poor quality belts now a days
 I make sure the belts I buy are from Mexico (so far the best quality I have found, used to be Gates brand were). Even still I can't get her car to stop. It only happens when she starts it for 30 seconds or more, then it's done. So weird.  My next step it to try the stop squeal spray stuff....

Good luck!

[Warren Seale]

You might want to check for pulley alignment.  If they are slightly off with each other then it will cause the squeak and eventually belt failure.

[5th T/A]

There have been lots of good suggestions from others. If the belt squeaks when you rev the engine or put a load on it, it’s probably not tight enough. The power steering belts tend to squeak when turning to full lock one way or the other. The PS bracket has a place to put a pry bar or long screw driver giving you extra leverage when tightening. Seems like alternator belts like to squeak on start up.

If you tend to hear a chirping sound without any additional load I would check belt alignment. An old fashioned yardstick works good for this. Lay it across the face of the pulley and look at where it lines up with corresponding pulley. The yardstick is stiff and won’t bend like a belt making misaligned pulleys more obvious. Since these cars are decades old it’s very possible that it’s been apart and reinstalled it with the wrong spacers.

[Zach]

After looking around I think they aren’t as tight as they should be, although there is a good chance the pulleys are misaligned. When the engine is running there is a slight wobble my assumption is everything that isn’t a common wear item is factory, everything I’ve taken off so far has been original. Thanks for the input I’ll look into it a bit more when I get out to the garage. Thanks.

[Zach]

Think I fixed it. Used a 20 year old curvy ruler I found and the pulleys seemed to be straight so that’s good. I used a 3 ft extension to pry the alternator tighter, don’t think I moved it much. Couldn’t find a good angle to use the curved peice of the power steering bracket so I had to pry it from behind against the alternator bolts, was able to get it tighter. Drove it, fast accelerations, revs, etc, not able to hear it in the driver seat so that’s good enough for me. Don’t think it’s squealing under the hood but didn’t check.  Thanks for the suggestions. Haven’t tested of it squeals still when I turn the wheel all the way but I’m not concerned about that it did originally, think my front wheels rub first anyways.

[Wallington]

The extra squealing when turning the wheel isn't from tyres rubbing, in this case, it's the increased load in the steering pump that finds a belt that starts to slip on the pulley instead.

[81Blackbird]

https://www.amazon.com/Gates-91107-Belt-Tension-Tester/dp/B000MUTAGS/ref=sr_1_1?crid=310RZZDLOSF7H&dib=eyJ2IjoiMSJ9.Am1xFYAhld3HjBSamMSjuXB2HFs9CclzQdwmwnac_dfWGERiEZgmbzDNhdcTn3PMTCvg-wh3HgPRvIRmvJd0Fx7ymvX83fHCU_NUn9MXpAwIXXmClYM8IFsf-96lG2lQf82rbGvoTg_1wDBGg_onuOUmSS1AGXkGoLOlSQ0I3px5JLXwO4FgJs9W1k_4IH-5QiA7FaZ03Cni5Vt8Br6wYOQi8OdT-emCyxBPZtXRXuD3tK_iX2QTSR3C1Z-o_aNBHmbT438Gmeksxz0BY-CLePGHdusHk2xmEEI2whoqWJw.SdK1kJXFhlBrNu0MO58MaHGzBkojw4yM8YggfgbGZ64&dib_tag=se&keywords=belt+tightening+gauge&qid=1726304094&sprefix=belt+tightening+gauge%2Caps%2C138&sr=8-1

[nUcLeArEnVoY]

Definitely make sure you have all your correct pulleys and spacers accounted for. It's easy for these parts to get mix and matched, or even lost over time with all of the variations of brackets/pulleys/spacers on Pontiac engines over the years. I was missing a 1/4" spacer from behind my PS steering pump and it was causing it to angle downward. Cross-reference all of the part numbers visible on your pulleys and brackets with a factory service manual. Also, the PS belt is actually supposed to be just a tad wider than than the alternator belt. If it's the same width, it'll sit too deep in the groove on the PS pulley and waterpump pulley.

The belts I use for my '79 W72 400...

Alternator: Dayco top-cog 15485
PS: Dayco top-cog gold label 17495

I get no squeeling whatsoever. And believe it or not, most people dramatically underestimate how tight the belts actually need to be and often end up way under-tensioning them.

[Zach]

Definitely make sure you have all your correct pulleys and spacers accounted for. It's easy for these parts to get mix and matched, or even lost over time with all of the variations of brackets/pulleys/spacers on Pontiac engines over the years. I was missing a 1/4" spacer from behind my PS steering pump and it was causing it to angle downward. Cross-reference all of the part numbers visible on your pulleys and brackets with a factory service manual. Also, the PS belt is actually supposed to be just a tad wider than than the alternator belt. If it's the same width, it'll sit too deep in the groove on the PS pulley and waterpump pulley.

The belts I use for my '79 W72 400...

Alternator: Dayco top-cog 15485
PS: Dayco top-cog gold label 17495

I get no squeeling whatsoever. And believe it or not, most people dramatically underestimate how tight the belts actually need to be and often end up way under-tensioning them.

Yeah my two belts are the same thickness, sits lower in the power steering groove. If it starts squealing again I'll get a thicker one. Seems to be OK for now.