2021 Silverado 1500 alternator/water pump belt issue

lapoolboy · February 16, 2022

Back in January I took my truck into the dealer to have a minor start-up squeal/chirp investigated. I knew it was the belt because I could see lots of black rubber belt "dust" all over the front of the engine behind the belt. I could also mist a little bit of water on the belt while the engine was running and the sound would go away temporarily. The technician determined it was a bad idler pulley so he replaced it but the belt was on backorder so he just reinstalled the same belt. The squeal/chirp immediately returned. I know these belts are one-time use only since they are stretch fit so I insisted on a new one. They ordered a new belt and it has finally come in. I'm just waiting on them to let me know when I can bring the truck by to have the tech slap it on real quick.

My concern is that there is a lot of the same black rubber belt dust on the engine again. Could this all be caused by the "used" belt slipping on the pulleys? Or is there an issue with alignment and/or another bad pulley?

voided3 · February 16, 2022

Ours was almost as bad as yours, and the belt started to go bad around 6300 miles. There was belt dust on the front of the motor similar to what you have pictured. They replaced the serpentine belt, idler pulley, and A/C belt. The truck is about to roll over 12,000 miles and while I see some of the same wear occurring again, I don't have a squeak like I did before yet; ours only squeaked/chirped rhythmically when it was cold for the first few minutes.

My guess is there may be some kind of alignment issue going on or something has a bad bearing, but it's hard to say. They didn't say anything about anything else being amiss when they replaced our belts, but I'm sure they had their finest apprentice on the job and they were not thorough enough to check the alternator or water pump, or the state of the crank pulley. I really hate that they didn't put traditional belt tensioners on these engines and part of me feel like it's a design flaw. It also makes it way more difficult to change a belt in an emergency situation.

Our other vehicle, a 2019 Mini Countryman with only about 12,600 miles, has essentially no belt wear and it looks brand new, while our truck already has been through one set of belts and an idler pulley in less mileage. The hilarious part is the truck's manual says it's a 150,000 mile service interval on the belts. HA.

lapoolboy · February 16, 2022

I agree with your sentiments. The A/C belt looks flawless and new. You can see it in the background of my picture - the markings/words on the back are still very clear and legible. To me, this indicates no amount of slippage or wear. The alternator/water pump belt on the other hand...

The back of that belt is completely devoid of any markings/words and you can see the wear on it.

voided3 · February 16, 2022

5 minutes ago, lapoolboy said:

I agree with your sentiments. The A/C belt looks flawless and new. You can see it in the background of my picture - the markings/words on the back are still very clear and legible. To me, this indicates no amount of slippage or wear. The alternator/water pump belt on the other hand...

The back of that belt is completely devoid of any markings/words and you can see the wear on it.

Right, which makes me think it must be the water pump pulley because the alternator, idler, and crank pulleys contact the ribbed side of the belt, so it's the only one touching the back of the belt. Maybe the cooling fans blast rain and road debris directly at it and cause it to slip when the weather is nasty? These trucks have active aero shutters, though, so you'd think that wouldn't be an issue.

On a side note, if anyone knows of a better-than-OEM serpentine belt upgrade for the L84 5.3 engines, I'm all ears and am certainly down to try it.

Transient · February 16, 2022

I've been saying it for quite some time now -- At least 1 of the pulleys is misaligned from the factory. 5.3s and 6.2s are having the same problem, but I hear more about squeaking from the 6.2 owners on this forum than the 5.3s. With that said, my dealer has only applied some dry lubricant per GM instructions. It did quiet down the squeaking a little. I'm still on the same belt my truck came with, and I'm at about 23,500 miles. It seems that if you let it wear down a bit it'll quiet right up, and there's been no other issues with the belt. A proper shim job, or proper aligning of the pulleys, would avoid this problem, but GM doesn't care. There is a business term "satisficing". It clearly applies here.

lapoolboy · February 17, 2022

I don't think a pulley misalignment issue would be eating up the BACK of the belt though, right?

Transient · February 17, 2022

1 hour ago, lapoolboy said:

I don't think a pulley misalignment issue would be eating up the BACK of the belt though, right?

I think it's possible given the back of the belt is the contact surface for 1 pulley. I'm no expert. It's just a thought. If the pulley isn't running parallel to the belt I could see some wear given the belt contacts over 180° of the pulley at all times.

Edited February 17, 2022 by Transient

voided3 · February 17, 2022

12 hours ago, Transient said:

There is a business term "satisficing". It clearly applies here.

I'm surprised that's not a trim package at this point: The Satificer

I'm also surprised that your dealer put anything on the belt as you're not supposed to put anything on a EDPM rubber belt like the "belt dressings" they would sometimes use on older style V-belts.

Perhaps in four or five years they'll admit there's a design issue and do a recall.

newdude · February 17, 2022

16 hours ago, lapoolboy said:

Back in January I took my truck into the dealer to have a minor start-up squeal/chirp investigated. I knew it was the belt because I could see lots of black rubber belt "dust" all over the front of the engine behind the belt. I could also mist a little bit of water on the belt while the engine was running and the sound would go away temporarily. The technician determined it was a bad idler pulley so he replaced it but the belt was on backorder so he just reinstalled the same belt. The squeal/chirp immediately returned. I know these belts are one-time use only since they are stretch fit so I insisted on a new one. They ordered a new belt and it has finally come in. I'm just waiting on them to let me know when I can bring the truck by to have the tech slap it on real quick.

My concern is that there is a lot of the same black rubber belt dust on the engine again. Could this all be caused by the "used" belt slipping on the pulleys? Or is there an issue with alignment and/or another bad pulley?

When they take that off to put the new one on, have them spin the water pump by hand and see how it feels. We've put a few on already, the one last night seized and fried the belt during its degredation.

Silverado4x4 · February 17, 2022

voided3 is right, belt dressing is a temp. fix for a bad belt and not good for those type of belts. I don't see it being an alignment issue as those belts will tear up the edges of the belt in an alignment issue and walk off the pully quick if not aligned right. I do see the ribs of the belt are cracked which means the belt is dry and probably old or some type of chemical got on it. There are plenty of better belts out there like Gates for one and many others. I would chalk it up to a bad old belt even though it was new.

Or as newdude said above.

Edited February 17, 2022 by Silverado4x4

diyer2 · February 17, 2022

How much $ per unit did GM save by removing the belt tensioner? X 1 mil. units.

voided3 · February 17, 2022

1 hour ago, diyer2 said:

How much $ per unit did GM save by removing the belt tensioner? X 1 mil. units.

Probably a lot, which I'm sure was the driving motivator. I can't help but notice that the gas L8T 6.6 V8 in the HD trucks have a belt tensioner, though. That always implies to me that it's a more robust setup if that's what they use in their HD fleet trucks, though those trucks also have hydraulic power steering pumps and sometimes dual alternators so the needs are different.

Transient · February 17, 2022

2 hours ago, diyer2 said:

How much $ per unit did GM save by removing the belt tensioner? X 1 mil. units.

GM is currently selling about 575,000 Silverados per year. Retail price aftermarket for a tensioner on a 2018 is about $40. To keep the math simple, assume 50% markup. $20×575,000=$1,150,000 per year savings, assumed. 2022 is the 4th model year of the current design, so approximately $4.6 million in savings to date.

diyer2 · February 17, 2022

What about GM trucks? That's why I said 1 mil. Just a number to make a point. Didn't look it up.

Transient · February 17, 2022

4 hours ago, voided3 said:

I'm surprised that's not a trim package at this point: The Satificer

I'm also surprised that your dealer put anything on the belt as you're not supposed to put anything on a EDPM rubber belt like the "belt dressings" they would sometimes use on older style V-belts.

Perhaps in four or five years they'll admit there's a design issue and do a recall.

SE = Satisficing Enough

They said the instructions came from GM. Whether or not they screw it up, because they did it they/GM will cover it. Until the truck is out of warranty, only Chevy dealers are touching it. Makes it harder for them to deny warranty coverage. Once the warranty is up the truck will be service by mechanics instead of technicians.

It took GM way longer than 4-5 years to acknowledge an ignition switch problem. You're being too optimistic.