Belt squeal (?) on cold start up on 2024 Chevy 2500HD 6.6L Gasser

[GMCustomerService]

On 4/6/2025 at 6:19 AM, 2500TB said:

My brand new 25 2500 6.6 L8T does the same thing on startup. I haven't tried taking it to the dealer yet. 

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[MudMonkey]

New air intake was installed and it didn’t fix it.  Per the TSB looks like GM is giving us the finger!

[AT4X Steve]

On 9/12/2024 at 2:44 PM, GMCustomerService said:

We regret to hear of this concern with your vehicle and would like to take the time to investigate further on our end. Please send us an email to [email protected]. Be sure to include your Username and Forum name in the subject line with additional details. We look forward to hearing from you. 

I have had mine in twice for the same noise...was told nothing wrong though the noise is obviously there.   Never had this on any other truck I have owned including other GMs.

[Tracker48]

On 5/17/2025 at 9:13 PM, MudMonkey said:

New air intake was installed and it didn’t fix it.  Per the TSB looks like GM is giving us the finger!

You can throw parts at it all day long. It ain't gonna fix it. Read the link I posted.

[jordan d.]

so I have the 2024 2500hd 6.6 gas as well. Same squeal except ive noticed it get worse over time. Doesnt last that long on start up. Maybe 3 seconds. I also "thought" it was related to the faint "turbo sounding whistle" everyone is talking about but today I noticed it wasn't due to acceleration but more so speed. It was windy today and when I felt the wind hit hard against me the whistling got loud. Found a video of a guy talking about his 2022 silverado and pointed out the foam in the door jams are poorly made that when going fast enough air escapes through and makes that whistle sound during "acceleration". Im bout to go check it out. At the same time the squeal at start up im kinda boggled on. But maybe ive found the culprit. My ac randomly started blowing hot at idle more so than not. But at high rpms it ice cold. I was able to process of elimate alot of ac components. I do know my serpentine is loose which im about to replace but also think that the cause is maybe the tensioner bearings on ac compressor. It just sucks cuz one the damn truck is brand new. 2nd alot of the sounds are similar and seem to be happening at once and its got me a little irritated. If anyone has any more info on these topics please share as we all together could pin point and come up with the solutions since these dealers dont wanna do the job they signed up for

Edited May 29, 2025 by jordan d.

[MudMonkey]

On 5/28/2025 at 5:42 PM, Tracker48 said:

You can throw parts at it all day long. It ain't gonna fix it. Read the link I posted.

The parts were ordered before the tsb came out and just now arrived.

[Ry Guy]

Mine does this as well. Never thought much of it and still don't.