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Shorter belt or replace AC bypass pulley? Help finding shorter belt?

CZroe

Lifer
Jun 24, 2001
24,101
781
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My mother's car broke down right before I left the country. A couple months later I find out that some pulley broke off and that the belt has been hanging out of the hood and getting weathered while being pinched/deformed.

The auto parts place asked me if she had AC or not because there were two different belts for that. They also needed to know what engine she had because the belts were obviously different between engines. The broken part was an AC bypass pulley so it seems like we could leave that out and go with the shorter "no AC" belt but they don't seem to have that option for this engine.

I ended up spending almost 3x as much only to see that the diagram indicates that there should be a shorter belt for this engine:


Try as I might, I can't find this part online. Perhaps AC was standard for this year model. Perhaps it's mentioned in the service manual, which I don't have. If anyone know how to find it, I would appreciate your help!

Since the belt needs to be replaced anyway it just makes sense to me that we get the right belt instead of going through all this again at 3x the price. The pulley mount that broke is made out of some brittle metal that's so crappy it feels like plastic and I doubt the new one will be any better.

Her car is a 1990 Oldsmobile Cutlass Ciera S with the V6 engine.
 
Jun 18, 2000
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Try as I might, I can't find this part online. Perhaps AC was standard for this year model.
Have you tried a different model year for the same gen and motor?

I thought most ac bypasses were 30-40 bucks. I'm guessing you are having it done and their charging a bunch for labor.
 

CZroe

Lifer
Jun 24, 2001
24,101
781
126
Have you tried a different model year for the same gen and motor?

I thought most ac bypasses were 30-40 bucks. I'm guessing you are having it done and their charging a bunch for labor.
I did a little poking but didn't find anything under the few similar years I checked. Was really hoping someone had a way to search by engine instead of by car, since the shorter belt is likely an option in some other model.


You're right: It's $40 but the longer belt is also more expensive. It needs a belt because she left it pinched under her hood with a significant portion being weathered in the summer heat for two months and now it's deformed.

It looks like a belt for no AC might be $15-$18 where the belt with AC is $22-25. Add $40 for the replacement AC bypass pulley and I'm paying four times as much as I would if I just got the right belt to start. I'm not hesitating because of labor fees (I'm doing it), but I hesitate to spend 4x as much just to have it break again a year down the road. I'm going to be kicking myself if I only had to ask online to find the cheaper belt but I'm prepared to just do it for $65+tax if the shorter belt is not available. I can still return it if someone points me to the right belt so it can't hurt to ask first. :)

These AC bypass pulley mounts are built out of brittle pewter junk. I don't know how the previous one lasted 3 years. I could literally break chunks off it with my hand.
 

mindless1

Diamond Member
Aug 11, 2001
5,627
523
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Your diagram doesn't show an A/C bypass pulley, was it just mounted about where the A/C would have been?

What is the origin of this vehicle? Was it bought new? I'm wondering why it has the A/C bypass pulley? It appears that A/C came standard on any with the larger (V6) engine.

Anyway, with A/C it's a 6 rib belt, .82" wide and .17" thick, and 108" long. You could measure the difference in length needed by going the alternate route and subtract that, then on a belt manufacturer's site, lookup what they have.

For example on Dayco's site, suppose you estimate you need a 74" long belt. I am making this number up out of thin air. Dayco shows 4 different belts with only an inch difference between shortest and longest.

Buy one locally then if it is too short or long, adjust accordingly and exchange it. Clean the pulleys ahead of time so the belt stays new looking and is returnable. The last three digits in the part # tell you the length so just change those digits.

http://www.daycoproducts.com/online-catalog-1?part_type=20
 
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CZroe

Lifer
Jun 24, 2001
24,101
781
126
Your diagram doesn't show an A/C bypass pulley, was it just mounted about where the A/C would have been?

What is the origin of this vehicle? Was it bought new? I'm wondering why it has the A/C bypass pulley? It appears that A/C came standard on any with the larger (V6) engine.

Anyway, with A/C it's a 6 rib belt, .82" wide and .17" thick, and 108" long. You could measure the difference in length needed by going the alternate route and subtract that, then on a belt manufacturer's site, lookup what they have.

For example on Dayco's site, suppose you estimate you need a 74" long belt. I am making this number up out of thin air. Dayco shows 4 different belts with only an inch difference between shortest and longest.

Buy one locally then if it is too short or long, adjust accordingly and exchange it. Clean the pulleys ahead of time so the belt stays new looking and is returnable. The last three digits in the part # tell you the length so just change those digits.

http://www.daycoproducts.com/online-catalog-1?part_type=20
Wow. I came back to share this, where someone already did this with a 74.5" belt, and I see that you pretty much nailed the length with your "thin air" estimate. Bravo! ...and thanks!

She's owned it since about 2004 back when the only thing wrong with it was a thief smashed the window to steal the stereo. It's had a lot of problems since but she still uses it (last two months, not so much). The AC compressor seized a few years ago and she elected to get the bypass pulley, so no mystery there. That's how I figure a replacement won't last long either and would rather just get the shorter belt.

Here's a video on how to measure for a serpentine belt. Get the length and take the old one with you to get the correct width and number of ribs.

https://www.youtube.com/watch?v=eoIHNo41DtQ
Thanks for the help. I think I have everything I need now. :)
 

CZroe

Lifer
Jun 24, 2001
24,101
781
126
For Google:
Dayco part number 5060745 currently over $25 at Autozone ($10 less than the 108" AC version)

Valucraft/Driveworks part 745K6 currently just over $18 at Autozone and Advance Auto Parts.
 

mindless1

Diamond Member
Aug 11, 2001
5,627
523
126
^ Never used a Valucraft but I like the Daycos for older vehicles because they have a felt-like lining that reduces noise. They're a little under $20 at Pep Boys after a 25% off promo code, but I would check to see if the same store has up to 1" longer and shorter in case you need to exchange it... just because someone else made a size fit, doesn't necessarily mean that they sized it right so that the tensioner has some range left to account for a little stretching (or wear as it settles down further into the grooves), or if your tensioner spring is weak, to not have that much range you might need it a little shorter.

https://www.pepboys.com/search/?term=5060745
 

CZroe

Lifer
Jun 24, 2001
24,101
781
126
^ Never used a Valucraft but I like the Daycos for older vehicles because they have a felt-like lining that reduces noise. They're a little under $20 at Pep Boys after a 25% off promo code, but I would check to see if the same store has up to 1" longer and shorter in case you need to exchange it... just because someone else made a size fit, doesn't necessarily mean that they sized it right so that the tensioner has some range left to account for a little stretching (or wear as it settles down further into the grooves), or if your tensioner spring is weak, to not have that much range you might need it a little shorter.

https://www.pepboys.com/search/?term=5060745
Well, it seems to be the same as Duralast (AutoZone house brand?). I got that by changing Duralast's 108.0" part number "1080K6" to "745K6" after seeing that 0745K6 doesn't work. The rest of the specs check out.

I tried 0745K6 at other sites too and it also only works when I drop the leading zero. Even then, I get a different brand, like "Driveworks" was from Advance Auto Parts. AAP is a big chain (though not nationwide) and it seems that's just one of their house brands.
 

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