chirping noise

[6.2 man]

I have a new 2019 denali 4 door 6.2, it just turned 2,000 miles and it has a chirping noise under the hood at start up most of the time.It sounds like a belt making noise and lasts for about 30 to 45 seconds .Took it to the dealer and they are saying it is in the exhaust and that GM is stating that it is normal. I have owned a lot of vehicles over the years and never had one or heard of one thats supposed to chirp for a while when started. Anybody else notice this also

[f8l vnm]

maybe DI ?

[Sierra Dan]

On the 2014-2018 K2 trucks like mine, the Adaptive Exhaust Valve A.K.A. exhaust flapper slightly before or after the muffler produced a Chirping

noise on startup and also during warm driving when switching from V4 to V8.

Some trucks have it, some do not.

 

[tommy1727]

I believe I have the same noise.  My dealer said “could not duplicate”.   I can hear it sometimes when going down the road if the radio isn’t too loud.  

[6.2 man]

I think your right on the exhaust flapper , mine does it but my buddies does not . 

[ShamrockShooter]

Clamp your adaptive valve open and give it another cold start and see if it goes away.

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[Thejet07]

Are there any negatives to clamping it open? Also, how does it sound open? Specifically, on the highway. I could hear mine. While it really doesn’t bother me, it sounds like the truck is cheap


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[ShamrockShooter]

With it clamped open the truck will be a touch louder, and you may get a hellicopter noise when it drops down from 8 cylinders.

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[Thejet07]

Definitely not looking to sound like a helicopter. Thanks


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[ShamrockShooter]

Definitely not looking to sound like a helicopter. Thanks


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I think the point was this was for troubleshooting to eliminate if the chirp was coming from the adaptive valve, so I would not be worried about the chopper noise.

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[OnTheReel]

On 3/8/2019 at 6:44 AM, 6.2 man said:

I think your right on the exhaust flapper , mine does it but my buddies does not . 

This sounds like a great excuse to buy a cat-back...

[Thejet07]

I think the point was this was for troubleshooting to eliminate if the chirp was coming from the adaptive valve, so I would not be worried about the chopper noise.

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I understand that. Difference is I would hear the helicopter while driving my long commute to work where as I only hear the chirp from outside the truck when I’m stopped or with window open. I guess ultimately I have to try it out


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[ShamrockShooter]

I have my 16 clamped open and tuned to turn off afm so no helicopter or chirp. Still pulling over 20 mpg at 70 mph with mud tires. If the adaptive valve is rattling or chirping the dealer may replace it under warranty. Mine has been replaced twice so far but the rattle always comes back.

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[DKSJLTrucks]

On 3/9/2019 at 7:41 PM, Thejet07 said:

 

I understand that. Difference is I would hear the helicopter while driving my long commute to work where as I only hear the chirp from outside the truck when I’m stopped or with window open. I guess ultimately I have to try it out


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I bought a new 2019 GMC Sierra SLT 6.2 about a week ago. Had the stock muffler, as well as the adaptive valves in front of and behind it removed.

 

Had a Flowmaster 50 Delta Flow Added for a nice deep tone to enhance my driving experience that would not upset the neighbors. 

 

I still hear a chirping sound on a cold startup and when the truck kicks off at a red light and starts up. I know jack sh*t about engines or any of this. I just love trucks... and hate chirping. The chirping reminds me of the exhaust of the VW Beetle from the 70’s. Thoughts?

[bshort]

57 minutes ago, DKSJLTrucks said:

I bought a new 2019 GMC Sierra SLT 6.2 about a week ago. Had the stock muffler, as well as the adaptive valves in front of and behind it removed.

 

Had a Flowmaster 50 Delta Flow Added for a nice deep tone to enhance my driving experience that would not upset the neighbors. 

 

I still hear a chirping sound on a cold startup and when the truck kicks off at a red light and starts up. I know jack sh*t about engines or any of this. I just love trucks... and hate chirping. The chirping reminds me of the exhaust of the VW Beetle from the 70’s. Thoughts?

Yep.  I have the GM cat back and hear the chirping too (on cold starts).  Seems to go away when warm.