Changed the Serpentine belt and pulleys.

__roger__

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Worked on my truck (SUV) today, and I am happy about it. I'm not a mechanic, but over the years I have been slowly building up my skills and experience. Everything went well, but I do have a question about belt sizing, see below.

There has been a loud (intermittent) high pitched whining/growling noise coming from under the hood. At, first I thought it was my transmission since it has hard shifts and leaks fluid. I'm not a mechanic so I assumed it was the transmission since I know it has been acting up lately. The transmission fluid was low so I filled it, and afterward the noise seemed to go away, but then it came back not too long. A friend told me it could be the serpentine belt pulleys. So I got both serpentine kits from Rockauto (the upper that contains a tensioner pulley, and idler pulley with a bet, and the AC tensioner pulley and belt). From what I read the Gates brands was supposed to be a pretty solid choice.

I was surprised how easy it was to change the components. The old pulleys did seem to be worn. One of the pulleys spun fast and made a hollow sound, and the other pulleys did not want to spin at all. I started the vehicle up after the maintenance and the engine engine sounded smooth. I will drive it to work tomorrow morning and hopefully the noise doesn't come back.

One issue I ran into was that I could not get the upper belt installed. It was too tight. I slacked the tensioner pulley all the way and still could not get it to go. I ended up having to use the old belt, and luckily it still looked pretty new. I read that there are at least two different sized of alternators, so maybe I have the larger one? I looked at the alternator before I bought the kit, and thought I identified it properly. I'll take another look, unfortunately, I don't remember if I thought it was the larger one or smaller one.

Question: is the new belt that goes around the crank shaft and alternator super hard to install when new? I think if I somehow would have gotten the new belt on it would have been way too tight, but idk.
 

__roger__

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Comparing the new belt vs the old might tell you if something is off. Otherwise checking to see if everything is set up correctly.
I noticed the old one was a little bit bigger. I wasn't sure how much a belt would stretch, but it actually did still look pretty new, so I'm guessing it wouldn't have stretched all that much.
 

stutaeng

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Should be within 1/4" or 1/2" of the original.

I remember once my mechanic replaced the AC compressor on my old 4.3 and he couldn't get the belt back on. We figured the remanufactured compressor had a different pulley, since that was the only thing that had been replaced. He went back and got a longer belt from Napa and all went well.

The LS has a separate belt for the AC compressor, so that doesn't apply, just an example of how things can throw things off.

You either got a different size pulley or wrong belt. Put the old tensioner to figure it out...
 

Mikloangelo

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Look up the RPO codes in the glove box and it will tell you what size alternator you have. They require different belt lengths depending which you have.
FYI, take a picture if the RPO codes and give it to AI to decipher. Much faster this way
 

AuroraGirl

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105 amp:
Dayco
5060923
Poly Rib Belt
Specifications

Description:
Poly Rib Belt​
Compound:
EPDM, Aramid Reinforced​
Backside Material:
Rubber​
Rib Depth:
Standard​
Top Width:
.82​
Metric Part:
6PK2345​
Number of Ribs:
6​
Rib Profile:
Straight Rib​
Thickness:
.169​
Effective Length (in):
92.32​

145 amp:
Dayco
5060930
Poly Rib Belt
Specifications

Description:
Poly Rib Belt​
Compound:
EPDM, Aramid Reinforced​
Backside Material:
Rubber​
Rib Depth:
Standard​
Top Width:
.82​
Metric Part:
6PK2360​
Number of Ribs:
6​
Rib Profile:
Straight Rib​
Thickness:
.169​
Effective Length (in):
93​
 

AuroraGirl

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3._SpecsPage.png
IMG_7388.jpeg
the first 2 are relevant, ignore the 160 amp one

U
 
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__roger__

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Thanks everyone. You have been a lot of help! I took a picture of my RPO codes and fed them to chatgpt:
Based on your RPO list, the key code here is:
  • KW1 – High-capacity generator (alternator)
For a 2006 Suburban 1500 with the L59 5.3L, KW1 typically corresponds to:
145-amp alternator (standard "high output" unit for SUVs with rear A/C, Bose, etc.)

I just confirmed my Rockauto order, and see that I actually orderd the 105 Amp belt. :confused:
At least I won't every forget what size alternator and belt I have.
 

Mikloangelo

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Thanks everyone. You have been a lot of help! I took a picture of my RPO codes and fed them to chatgpt:
Based on your RPO list, the key code here is:
  • KW1 – High-capacity generator (alternator)
For a 2006 Suburban 1500 with the L59 5.3L, KW1 typically corresponds to:
145-amp alternator (standard "high output" unit for SUVs with rear A/C, Bose, etc.)

I just confirmed my Rockauto order, and see that I actually orderd the 105 Amp belt. :confused:
At least I won't every forget what size alternator and belt I have.
Bummer you ordered the wrong one. But at least you know now, and rockauto may refund you if you are still within the window.
 

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