Belt Squeal
#1
Belt Squeal
Hi all, I have a 455 in my cutlass that was originally a 350. I have the pulleys lined up perfectly but the alternator belt still squeals. I know it is this belt because back when I couldn’t get the car to charge I just pulled the alternator and belt out and ran the car off the battery, with no squeal during revs. Is there any fix for this belt squeal? It’s horrendous.
#5
Did you tighten the alternator belt correctly?
https://classicoldsmobile.com/forums...pulley-139553/
https://classicoldsmobile.com/forums...t-loose-51844/
https://classicoldsmobile.com/forums...pulley-139553/
https://classicoldsmobile.com/forums...t-loose-51844/
There are THREE fasteners that you need to loosen to adjust the belt, the two bolts on the front and the one nut at the bottom rear of the pump. Once you loosen all three, use a large screwdriver as a pry bar and insert it between the nose of the pump and the tab on the bracket, between the pulley and the bracket. The photo shows the proper position of the screwdriver with the pulley removed for clarity. Use the screwdriver to tension the belt while tightening the two bolts on the front, then get the nut on the back. Failure to do this properly is why there are frequent posts about belts squealing.
![](https://classicoldsmobile.com/forums/attachments/general-discussion/56553d1352041292-problem-alternator-belt-slipping-ps-pump-adjustment-sm.jpg)
![](https://classicoldsmobile.com/forums/attachments/general-discussion/56553d1352041292-problem-alternator-belt-slipping-ps-pump-adjustment-sm.jpg)
Last edited by Fun71; July 20th, 2022 at 08:55 AM.
#6
Belt size, condition and quality really matter. The belt must be the correct width and length. The width is often overlooked. If the belt is down in the pulley it is probably too narrow. Look at the sides of the belt for glazing.
Good luck!!!
Good luck!!!
#7
Hi all, I have a 455 in my cutlass that was originally a 350. I have the pulleys lined up perfectly but the alternator belt still squeals. I know it is this belt because back when I couldn’t get the car to charge I just pulled the alternator and belt out and ran the car off the battery, with no squeal during revs. Is there any fix for this belt squeal? It’s horrendous.
#8
I'm having the same issue on my 350 - Initially had start-up squeal that would last for a couple of early park-idle throttle blips before going away. Adjustments to the existing belts didn't cure so I replaced all 3 with new Gates XL and readjusted each applicable component tension (A/C compressor, p/s pump, alternator). Compressor is a Sanden for the Vintage Air system, alternator is a Powermaster 100 amp (si series internal regulator).
All pulleys properly aligned and clean
No free-spinning pulley problems or voltage issues with the alternator day or night.
Now I seem to have eliminated the start-up squeal but it's occurring at higher RPM ranges somewhere approaching 3k.. Frustrating...
All pulleys properly aligned and clean
No free-spinning pulley problems or voltage issues with the alternator day or night.
Now I seem to have eliminated the start-up squeal but it's occurring at higher RPM ranges somewhere approaching 3k.. Frustrating...
#9
I'm having the same issue on my 350 - Initially had start-up squeal that would last for a couple of early park-idle throttle blips before going away. Adjustments to the existing belts didn't cure so I replaced all 3 with new Gates XL and readjusted each applicable component tension (A/C compressor, p/s pump, alternator). Compressor is a Sanden for the Vintage Air system, alternator is a Powermaster 100 amp (si series internal regulator).
All pulleys properly aligned and clean
No free-spinning pulley problems or voltage issues with the alternator day or night.
Now I seem to have eliminated the start-up squeal but it's occurring at higher RPM ranges somewhere approaching 3k.. Frustrating...
All pulleys properly aligned and clean
No free-spinning pulley problems or voltage issues with the alternator day or night.
Now I seem to have eliminated the start-up squeal but it's occurring at higher RPM ranges somewhere approaching 3k.. Frustrating...
#10
I installed new Gates altenator and power steering belts on my 66 Cutlass. No problem with the the altenator belt however the power steering belt really squeked. I finally was able to put enough tension on the power steering belt and the squeal is gone. It takes a lot of leverage on the power steering belt set up to get the least amount of belt deflection of 1/2 inch. Runs fine now with no squeaks for the last month.
It wasn't the belts.
Wayne
It wasn't the belts.
Wayne
#11
I installed new Gates altenator and power steering belts on my 66 Cutlass. No problem with the the altenator belt however the power steering belt really squeked. I finally was able to put enough tension on the power steering belt and the squeal is gone. It takes a lot of leverage on the power steering belt set up to get the least amount of belt deflection of 1/2 inch. Runs fine now with no squeaks for the last month.
It wasn't the belts.
Wayne
It wasn't the belts.
Wayne
#12
It’s been my experiences every time a belt squeals it’s because it’s too loose - every single time. When a belt which has never squealed on piece of equipment begins to squeal it’s because the belt has stretched and has lost tension and it’s time for a new belt. I’ve bought replacement belts which were unsatisfactory and started squealing - a couple disintegrated in very short order. On those occasions I carefully reviewed the characteristics of the belts. They did not seat low into the pulley grooves - they were riding far too high and literally continuously slipping. Wrong belts for the application for whatever reason - mislabeled, bad manufacturing or whatever. My point is they were not tight enough. Be sure your belts sit deep into the pulley grooves and are very tight - they should not ride high in the grooves, if they do they will continually slip and squeal like an old stretched out belt.
#13
#14
I would tend to agree in principle that tighter is better but in practice, not always the case. I've tightened my brand new belts to the most minimal deflections possible and all it's done for me is shift the squeal threshold from occurring at start-up to occurring at speed during moderate accelerations approaching 50-60mph.
and at this point I don't want to attempt further tightening for risk of stressing component bearings - so I'll give it some time and maybe swap out to different belts again if no change in status.
and at this point I don't want to attempt further tightening for risk of stressing component bearings - so I'll give it some time and maybe swap out to different belts again if no change in status.
#15
A squealing belt is slipping because it’s too loose. There’s reasons it can be slipping (not enough tension), but it’s never because it’s too tight. And, when it’s slipping it’s definitely heating up.
#17
#20
I have a variation on this but the belt will only squeal when the engine is good & hot at speeds above 3,000 RPM. 69 Cutlass S convertible with the Rocket 350. Factory A/C car but AC compressor has been removed. I haven't tried the screwdriver behind the P/S pump pulley yet. How tight should it be? It seems my belts are pretty tight but, obviously something is amiss.
#21
Firstly ensure you have the correct belt - a belt which rides into the "V"alley of the pulleys - not a belt which rides too high above the "V"alley. An improper belt (esp. one which rides too high) will often tend to produce a squeal as it does not "fit" into each pulley "V"alley.
Secondly, addressing how tight it should be, you can tighten these belts "a lot". Use the screwdriver method. You should have no more the 1/2" deflection (up & down & laterally). With your hand/fingers at the mid-point of the length of the belt, you should not be able to turn (twist) the belt greater than 1/2 turn.
Secondly, addressing how tight it should be, you can tighten these belts "a lot". Use the screwdriver method. You should have no more the 1/2" deflection (up & down & laterally). With your hand/fingers at the mid-point of the length of the belt, you should not be able to turn (twist) the belt greater than 1/2 turn.
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