AC belt size or part number?

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mattbta

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Decided to replace AC belt and tensioner since I was experimenting with serpentine belt sizes for my Mechman 240a alternator. 2004 Tahoe, CJ2, auto front/rear HVAC.

Delco part finder pointed me at:

I cross referenced to Goodyear and purchased from AMZN. (960mm ~= 37.8")

Yeah, that one wasn't going on at all. I didn't want to ruin the belt forcing it on and the tensioner was turned to the max. Any ideas on what P/N I should grab? Just go for OEM? Getting a little tired of ordering several different belts after finding wrong information on what my serpentine belt length was (145a) trying to get the proper tension for the Mechman.
 

afpj

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I have had that happen many times with aftermarket belts. I've since learned to just stick with oem. Costs more, but I can install it without cursing.
 

adriver

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Just so it's clear, there are two sizes of belts and alternators. There is a small and large case alternator. The small case is a 105 amp alt. The 130/145/160 amp alt is the large case. (I also have a mechman 240 alt and it is the large case, as are just about every aftermarket alt unless you had one specifically made from the small case). The larger case alt has the pulley in a different location, and requires a belt that is 3/4" longer than the small case belt. (Not all places you order from, acknowledge there are two size belts and why).

The smaller belt will physically install on the larger case, but causes increased tension. It can cause belt slipping at higher RPMs, harder starting and increased wear on the tensioner and alternator.

I can tell you the RPO code for the 105 amp alt is K68. (K34 is cruise), but any other K code SHOULD be a larger alt, but check it first, and you might be just replacing the same size if you don't already know. If you already have the 145a case, then you should already have the larger belt.

I know mine is 4060930 - Continental Gatorback poly v belt. No squeal, works great. Just replaced mine after 6 years and 55k miles, because it felt like it was time, but still looked pretty good.
 

afpj

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I'm not sure but isnt the ac belt the same size regardless of alternator?
 

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