STRETCH DRIVE AND A/C SERPENTINE BELTS

[SIXFOUR]

After driving my 2020 GMC 1500 Denali 6.2L for several thousand miles (I bought as CPO 65k miles), I was surprised to learn that they are stretch belts and there is no longer a tensioner pully. There is an idler, but once stretched on, no other adjustments able, or needed. For others, what are your thoughts and experiences in installing and the wear or life expectancy you have had with them.

Thanks, Mark

Edited September 29, 2025 by SIXFOUR

[2016 Sierra Owner]

There are hundreds of thousands of these stretch belts on the road right now. If they were failing early. There would be a thread a mile long on here saying my stretch belt failed at ****** miles, my belt just broke, or I've had x belts replaced in the past year. 

[newdude]

They've been pretty reliable.  The AC compressor belt has been a stretch since like 2007/2008 on GM V8s so it was only a matter of time.

 

That said, these do have some occasional idler pulley failure.  

[redwngr]

And of course the spring loaded idlers also have bearing failures.

[Transient]

Over 90k on my odometer.  No belt replacement needed so far. 

[silveradosid]

105 k miles and still original belts, but i am think of replacing them for piece of mind

[RyanbabZ71]

Ive thought about going this route

 

https://www.ictbillet.com/products/lt-truck-2019-up-belt-tensioner-idler-kit-5-3l-6-2l-silverado-l84-l87

 

 

[redwngr]

Stretch belt install/removal is tool is about $30 and fits in the glovebox or pocket in rear seatback or.... 

 

This one is a Lisle

 

[Gangly]

I'm at about 160K miles on my 2020 5.3, and it likes to shred a belt about every 40K miles on the dot.  I do not believe that to be a belt issue, but more of an idler pulley issue and alignment.  I keep a NIB spare belt in the truck, as well as heavy duty zip ties, and I use the zip ties for getting the new belt on in an emergency.  I purchased a cheap tool to replace the belts, but it was more trouble than it was worth so I just use the zip ties now.

[RyanbabZ71]

22 hours ago, redwngr said:

Stretch belt install/removal is tool is about $30 and fits in the glovebox or pocket in rear seatback or.... 

 

This one is a Lisle

 

 

Zip tie method works 1000x better than these "specialized" tools.  

[johnnyquick]

On 10/16/2025 at 8:30 AM, RyanbabZ71 said:

 

Zip tie method works 1000x better than these "specialized" tools.  

AGREED!

I just did mine ac and serp, the tool is a PITHA and when you drop it a few dozen times, you end up grabbing zip ties anyway and YES do the idler at the same time.

[SIXFOUR]

I also have a variety of the stretch belts install tools. The tools work sometimes, and the zip ties are a pain too. I replaced my belts at about 75K, and they were getting thin. I also replaced the non adjustable idler, just so I  don't have to go back and cut the belt off. The accessory belt was very stretched out and thin compared to the new one. They were the original serpentine belts. It might be a simple task with a lift, but it is more frustrating laying on your back to get them on. It is what it is. I know how to do it now, but not my favorite thing to do at all.