factory -> high output alt, longer belt needed

Lv1G6He3V2 · May 6, 2012

GMT-800 '99 Sierra 1500 non-HD 5.3L V8

I have the factory alt (105 amps?) and purchased a rebuilt alt online (275 amps). Seller rebuilds amps for lots of vehicles, and I was assured the new alt would be a drop-in replacement.

We 2 hours spent trying to get a new belt to fit, then the old one - never replaced a serpentine belt before so we thought there must be some trick to it.

Put the old alt on, and the factory belt slid on easily. *sigh*

Model number on the factory belt is PK2345 EB and has 6 splines (?). The 2345 is length in mm.

Both pulleys are same size - 2 3/8" if I remember correctly - but what I failed to notice earlier is that the alt housings are different heights. I'm thinking the new alt would've been a drop-in replacement for an HD truck, maybe one with plow options or something.

Anyway what size belt do I need? Is there a standard size for this?

I don't want to guess...seems like a poor-fitting belt would cause unnecessary wear. Maybe the tensioner mitigates minor belt length differences, I dunno.

txab · May 6, 2012

Try:

AC Delco 6K930 93 5/8"

Gates K060930 93 5/8"

Goodyear 4060930 93.75"

93 5/8" long compared to 92 7/8" long for your original belt

Lv1G6He3V2 · May 6, 2012

Thank you! I ordered a Goodyear 4060930.

Funny thing: I almost ordered this belt originally, before figuring out the factory model #. It would have worked by accident with the new alt.

tesnoboy · May 6, 2012

You need the belt for a High Output Alternator. The casing is larger, hence making the belt larger. That's a serious alternator you bought. You plan on running a laser cannon with it?! While you have it apart check your AC belt for wear and your tensioners. Mine were starting to seize up and making noise. If they seize they can snap your belt and cause serious damage under hood. Good luck!

Lv1G6He3V2 · May 6, 2012

AC belt tensioner was like new - cast areas were like factory-new, so it must've been replaced by previous owner - and we replaced the AC belt yesterday. LOL 3 hours to put in new alt and change 2 belts, and the only thing we accomplished was to change the AC belt.

I do have a rattling noise when AC is on but the mechanic who had checked it out said the compressor is failing - not sure what/when to get that fixed but I imagine the bill will be substantial.

tesnoboy · May 6, 2012

Yup, AC costs a fortune to fix. Mine has never worked right.Hope you don't live down South where AC is a necessity.So what do you need all those amps for?

waumo1 · May 6, 2012

I do have a rattling noise when AC is on but the mechanic who had checked it out said the compressor is failing - not sure what/when to get that fixed but I imagine the bill will be substantial.

Our 2002 Yukon compressor started making a rattling noise shortly after the warranty was out. It was still rattling 5 years later when we traded it off.

Lv1G6He3V2 · May 6, 2012

Yup, AC costs a fortune to fix. Mine has never worked right.Hope you don't live down South where AC is a necessity.So what do you need all those amps for?

Temps are 95-105 F in summer, very hot although I've heard that in desert states 115 F is normal.

As for the amps, we need some serious juice to fire up the bed-mounted jet engines.

Seriously I'm thinking e-fans, HIDs, and speakers - then maybe try something computer-related in the cab. Why do a small upgrade if it doesn't work right after all the accessories are installed? 'Course I'll end up doing it twice anyway since the larger alt needs a bigger belt...live and learn.

Lv1G6He3V2 · May 6, 2012

Our 2002 Yukon compressor started making a rattling noise shortly after the warranty was out. It was still rattling 5 years later when we traded it off.

You mean it worked fine even though it rattled? I wonder if the problem is internal or external (maybe how it's fastened?).

waumo1 · May 6, 2012

Our 2002 Yukon compressor started making a rattling noise shortly after the warranty was out. It was still rattling 5 years later when we traded it off.

You mean it worked fine even though it rattled? I wonder if the problem is internal or external (maybe how it's fastened?).

Yes it worked fine and the sound was internal. I decided to just let it fail but it did not. The parts guy at the local GM dealer said they kept them in stock due the fact they were prone to failure.

I have had the old GM A6s that the valves rattled like crazy also but they continued to work for years also.

sonjaab · May 7, 2012

Possibly because you went from a CS-130 to a cs-144.... thats why the housing is bigger.

Ask for a belt for a 2500 6.0 with the vyu plow prep option.

They have the 150 or 160 cs-144 unit.

Lv1G6He3V2 · May 12, 2012

Thanks everyone!

I'll leave the compressor alone. Only thing that I saw is that the retaining strap (?) is badly rusted.

My new belt arrived and installed fine w/ high output alt. The truck sounds quieter (at idle, hood up) with the gatorback belt; the stock electronics appear to work fine and dash battery meter is steady. Since the big three are done and the new alternator is in place, we should be ready to do an electric fan conversion.