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Slipping and squealing V-belt


old-tank
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Slipping and squealing V-belt:  not specifically Buick (but don't move the post since Buick guys are the smartest :P).

AC belt on my 76 Olds 455.  Tried 3 brands of belt with no change and 2 different belt dressings that help...for 20 miles.  Pressures are reasonable.

It started when I replaced a leaking and slobbering A6 compressor and the oil (ester) and desiccant bag in the VIR system and charged with R134a.  Research showed that the old VIR system will not work with other than R12, so I changed to a cycling system...still slipping.  Replaced the condenser with a parallel flow unit...still slipping.  Replaced the compressor 3 times and ended up with the A6 upgrade unit (big old ugly aluminum unit).  The cooling is great with no slipping as long as I drive carefully and less than 60 mph.

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I went to Rock Auto to see what they had for belt options.  Interestingly, reading the technical descriptions seems to indicate a difference of opinion with regard to design philosophy between Gates and Dayco.

 

Here's what Gates says about their belt:

image.png.fc6227af8b77485f7e8899ff044d7276.png

 

And here's the blurb provided by Dayco:

image.png.a3885751df349bdc5ecb9acfeca9610f.png

 

Note that Gates claims: "Due to thermal forces, this variable notched belt tightens on the drive as it gets hot. This results in improved belt performance by reducing tension decay and noise."

 

On the other hand, Dayco says: "Dayco® was first to develop a v-belt with the raw edge sidewall construction, which facilitates controlled slippage around pulleys."

 

Based on the claims above, I'd be tempted to give the Gates XL High Capacity V-Belt a try...

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I tried Gates AC Delco and one from Off-road belts.  I may have to try the Dayco since the other designs did not work.  I did not consider the dayco since judges did not like that design on one of my projects I submitted for judging.  If that doesn't work I may have to

 rig an idler pulley to increase the wrap on the air conditioning compressor pulley.

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My '67 Riviera is like your Olds; single belt and not much contact area.  It has to be very tight or it squeals.  Did Olds use a double pulley setup on any cars that would be a candidate to swap to your '76?  The idler might be simpler than a wholesale pulley swap, though...

 

Are you sure the belt is tight enough?  New belts will stretch a lot at first, which means a lot of re-tightening until it is fully broken-in.

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Did you flush the system with a solvent for Freon systems. I can’t think of the name of the flush we use at the moment. With a bit of oil left in the condenser or evaporator it will build up with each new component. It is possible you have an oil over charged system.  I Had a York compressor with 2 V belts would not stop making belt noise. Flushed system added correct amount of oil and it stopped talking back.  Just a thought 
 

The flush is needed if Changing oil types did this have Pag oil when new?
Steve 

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By observation, GM usually spec'd the nothced belts for applications where the pulley was smaller (as in Cadillacs with the small pulley and 100amp alternators).  Not sure why a belt would get tighter if it gets hotter, all things considered, but I could understand a rubber compound which might get grippier with additional heat.

 

Has it been determined if it is the a/c pulley that's slipping or another one?  Perhaps the "leaked" a/c oil bonded with the pulleys and might need to be "vatted out"?  Never did have any luck trying to use "belt dressing compound" to fix a slipping belt, although others claimed to have good luck using it.

 

Curiously, are the new belts .380" width or .440" width?

 

Just some thoughts,

NTX5467

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Think it's time to check A/C system head pressures, since it appears the system is all R134a now.

 

Rule of thumb when converting from R12 to R134a. Whatever the R12 design capacity of the system is, use 75-80% of that amount for the R134a charge. Example spec is 4 lbs R12, put 3 lbs R134a in. Otherwise you develop outrageous high side pressures, which can cause belt slippage and eventually clutch/compressor failure and leaks.

 

I never did like those Valves-in-Receiver systems.

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On 9/9/2022 at 7:38 PM, old-tank said:

I tried Gates AC Delco and one from Off-road belts.  I may have to try the Dayco since the other designs did not work.  I did not consider the dayco since judges did not like that design on one of my projects I submitted for judging.  If that doesn't work I may have to

 rig an idler pulley to increase the wrap on the air conditioning compressor pulley.

Dayco belt is working so far.  So much for the marketing propaganda of the other belts.

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