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79 Estate Wagon, AC Compressor belt slack and bounces


MrEarl
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403 engine in my '79 Estate wagon. Recently had the timing chain replaced and now can't get slack out of the AC compressor belt when the AC comes on. It's only slack between the compressor and the crank, stays tight between the compressor and the water pump.  I've tightened it TIGHT, I've loosened it, I've installed a new belt double checking the part number, the pully alignments are good.  I've always had "a little" slack between the compressor and the crank with the AC on,  but not this much. AC runs COLD, the compressor (as well as the complete AC system)  has less than 500 miles on it but I'm wondering if possibly the compressor clutch is starting to go bad and is starting to seize. Any thoughts ?

 

 

Edited by MrEarl (see edit history)
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I am not claiming to be right about this, but that looks like a lot of flexing to me. My belt on the Queen does the same but I don't think as much as that.  

Is the belt wide enough?  Seems to be pretty deep into the compressor pulley.  

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13 hours ago, old-tank said:

What be are the pressure readings in the A/C system?  What refrigerant?

The more resistance to turning the more that section will flop.

It is actually not much different than my Olds 455 has always been.

  It's 134 Willie but don't know the pressure. Last resort will be to carry it back to the shop that did the complete AC change out and ask them to check it.

I was actually hoping you would weigh in with a comparison to your Olds. Thanks!

 

 

13 hours ago, SpecialEducation said:

If it’s not slipping and it’s not throwing the belt, leave it be. 
 

I’ve seen expensive damage done from over-tightening belts because a mechanic thought “that just doesn’t seem right.” 

 

Good point. At one point when I had tightened the piss out of it the compressor started chattering so I quickly backed off. As it is now the belt at times actually comes into contact with the rubber gas lines. I also just recently changed the fuel pump so not sure if maybe the hoses are a bit differently routed. If I can't get the belt to stop jumping so much i will definitely move the gas lines. Thanks!

 

 

 

12 hours ago, JohnD1956 said:

I am not claiming to be right about this, but that looks like a lot of flexing to me. My belt on the Queen does the same but I don't think as much as that.  

Is the belt wide enough?  Seems to be pretty deep into the compressor pulley.  

 

It looks to be more flexing than I ever recall it having JD. The current belt is a new Dayco and is one I had bought as a spare to carry in the car. It was not my first choice but all the parts store had when I was buying. Thanks JD!

 

 

I have an ACDelco and a Gates XL High Capacity coming from Rock Auto, hopefully one of these will help

 

Curious, does anybody know if standard v-belts or cogged belts (which is pretty much the market standard today) came on these vehicles when new.

 

 

 

 

 

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7 minutes ago, MrEarl said:

It's 134 Willie but don't know the pressure. Last resort will be to carry it back to the shop that did the complete AC change out and ask them to check it.

I was actually hoping you would weigh in with a comparison to your Olds. Thanks!

R-134a runs higher pressures than the original R-12, so much on my Olds that the belt slipped.  There really should be 2 belts like my 55 factory A/C.

When I put A/C in my (nailhead powered)  51 F-1, I used the old mount system from my parts car.  That setup used an idler pulley between the crank and a/c pulley that I did not use at first and that belt belt flopped some much that it roared at certain speeds...no problem with the idler pulley.

 

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20 minutes ago, avgwarhawk said:

One that will give you a bit of hell getting over the clutch assembly

  
funny that you would say that as the one that was on it WAS shorter and a bit wider and was installed when I first changed out a bad compressor and went to 134 from r12 and as Willie mentioned was experiencing slipping/squealing. I did actually experience some hell trying to pry and get it off until I pulled out the box cutter. 😬 But even it was giving the same jumping problem.  
 

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Wow, thanks for doing that JD!!!  Yea, while I think mine is flopping, jumping, bouncing, hopping, vibrating profusely or whatever one wants to call it a bit more than than yours, I'm just going to try the three new ones that are on their way and use the the better of the three, pull the fuel lines back a bit and move on probably. I'll report back how it goes though. THANKS

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Smaller width belts do seem to flop around more. I think they used to be more like 5/8” at the top of the belt and now they seem like a “metric half”. 
The belt top should not have cogs on it for a ‘79. Those and universal ribbed radiator hoses (along with red heater hoses and yellow spark plug wires) always reek of somebody who restored their cars from Pep Boys instead of Napa (if that makes sense). 

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5 minutes ago, buick5563 said:

I think they used to be more like 5/8” at the top of the belt and now they seem like a “metric half”. 

Yep.  I saved and still carry the original belts from my 76 Olds (what's a silly millimeter or 2 among friends?).

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Here are the three belts I have coming from rock auto. The first one is the widest and shortest one, the same as the one that had helped reduce slipping/squealing. Still jumped though

 

EA86D6A0-A65F-4D5D-9DAA-41923C0E138C.thumb.jpeg.907eed6574f8f8ecf6d33ce737e5193d.jpeg

 


The next two are the same size, length and width as what I have on there now but of better quality. One is standard, 

 

A6A622CA-48AE-4460-A70F-BFAF1587F36A.thumb.jpeg.00bd456868304c19685ef9b9e3582d4f.jpeg

 

 

one is XL - High Capacity , I have hopes for this one. 

  
F5315B8E-D662-46C0-A761-AB58D4F21D79.thumb.jpeg.1147b2b2f840c47f1cc97a43c9550c79.jpeg

 

 

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On 4/15/2020 at 4:40 PM, buick5563 said:

They are marked with 7650 XL. I believe the XL designation is 5/8 top width.

  

No, the 650 is 65 inches effective length. The 7 is 10mm or .41" top width.

https://www.gates.com/us/en/search.html?searchType=product&text=7650+xl

 

A 9 as a first digit is wider than a 7. In Earls' pictures you can see it is 12mm wide.

 

In Dayco, 15 (as in 15650) is .44" top width.

http://www.daycoproducts.com/part?findtext%3D15650%26part_number%3D15650

 

In Dayton the wider belt starts with 17 instead of 15. A 17650 is .53" wide.

 

XL is  a better belt, like High Capacity then a regular 7650. Of course, now Gates does not sell a 7650 anymore, all replaced by XL series. Too many products to carry.

 

When changing top width, the belt rides in the groove at a different height, and usually the belt length needs to be changed also.

 

A true 5/8" wide v-belt is a 5L or B series belt. Haven't seen one on a modern car. Only in industrial settings. OK, B is actually 21/32"......

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  • 3 months later...

Sorry, forgot to report back. I further tweaked the alignment of the compressor pulley with a few washers then tried the three belts referenced above. There was no appreciable difference even after realigning the pulleys nor after swapping to both the .41 width/53.08 outside length standard and HD belts however the .47 width/52.38 length (shorter) did seem to help a bit,  BUT there is still more slinging than I think there should be.   I've not had a re-occurrence of the belt squealing nor of the clutch rattling, the AC is filling the huge glassed greenhouse interior of the wagon with cold air so with a spare rebuilt Delco compressor in the back storage I'm calling it good.  I'd love to find another 403 wagon with a radial compressor to see literally how their belt acts.   

Edited by MrEarl
there to their (see edit history)
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You haven't seen "belt flap" until you've seen a dual-belt '60s Chrysler B/RB engine a/c belt (which also means R-12).  Originally, they HAD to be matched belts from the same batch.  At "road speed" rpm, they'll have harmonics and even slap each other, but no jumping off. 

 

Similar with the 5.7L: Olds diesels, too.  Except that there was a special hose clamp for the diesel thermostat housing end of the upper radiator hose, with a built-in shield to protect the hose.  Chrysler added a idler pulley/tensioner on the later '70s cars.

 

After the belt runs for about 30 minutes, re-set the deflection/tension and let it go.  Might move whatever line/cable that's close to it, though, for good measure.

 

GM used either 3/8" wide belts or .440" wide belts back then.  IF the production belt was a .380" wide belt, use that length and add 1" to it for a .440" wide belt.  That extra inch of length is necessary as the .440" belt rides higher in the groove, so it needs to be a bit longer, from my experiences.  The greater mass of the .440" belt might change the harmonics of the situation, but probably not.

 

So, run the belt a while, let things cool down (even over-night), then re-set the tension TO SPECS and let things be good.

 

Enjoy!

NTX5467

Edited by NTX5467 (see edit history)
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Just remember that tight belts put more load on the bearings of the particular component AND other items that belt runs.  Which is why "tight" can be too much, but "loose" makes the belt slip.  

 

Years ago, I happened by my machine shop operative's place.  He told me that he'd taken apart a Chevy 400 small block and that the bottom half of the front main bearing was still new, but the top half was worn.  I asked how that could be?  He replied, "He kept the drive belts too tight.

 

From about 1959 until 1967, Chrysler had an unusual power steering pump mounting.  It was not solid, but was designed such that when a load was put upon the pump, the pump would lean into the belt, thereby letting it run "looser" until more tightness was needed.  The belt was a bit wider, too.  AND it worked as designed!  Except that many customers thought the belt shouldn't be that loose, so they had it tightened to what they suspected it should be.  Which resulted in the rubber bushings that made it work deteriorated.  Whch then resulted in the pump sitting cock-eyed.  BUT it still worked as designed!  The fix?  Weld it solid.  I know it looks like it's ready to fall off, but as long as it works, that's fine as I know why it's sitting that way.

 

Back then, it was somewhat common to hear power steering belts squawk in the shopping center parking lots, usually GM cars.  Very seldom a Chrysler or Ford product.  The power steering pump on my '77 Camaro has a dedicated belt plus is helped by the a/c belt.  Perhaps the p/s pump is an additional tension pulley for the a/c belt?

 

Use fresh-production belts rather than "fresh-to-you".  Quality brands with quality construction and rubber.  Tight enough to not slip, but not tight enough to wear out bearings in other components later on.

 

Enjoy!

NTX5467 

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Relocate the compressor down low near the crank pulley; or fabricate a means to install an idler pulley between the compressor and the crank pulley; live with it as long as it is not contacting other components like the radiator hose.  It is gonna flop!

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Does the 403 have the aux vacuum pump as the Olds 307 does?  How do the belt routings differ between those two set-ups?  Just curious . . . 

 

Probably best to leave this one as Madam General designed it.  Remember, EACH design underwent lots or testing before it was approved for production, although sometimes it has seemed that such development time was minimal, by observation.

 

NTX5467

Edited by NTX5467 (see edit history)
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On 4/14/2020 at 10:58 AM, old-tank said:

When I put A/C in my (nailhead powered)  51 F-1, I used the old mount system from my parts car.  That setup used an idler pulley between the crank and a/c pulley that I did not use at first and that belt belt flopped some much that it roared at certain speeds...no problem with the idler pulley

Rerun.. 

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efffin rotated at certain speeds 😆 tha’s a hoot! I think I’m good then! Much more to worry bout these days. I’ll just drive til it flys off... thanks for all the great sharing of knowledge guys, love ya all !!!

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