6.2L Squeak/Chirp/Sputter Sound (Engine Area) and GM Service Bulletin

[Maduro8]

So I just discovered on my new AT4 (1000 miles) an interesting sound that occurs at very specific conditions.

At very low throttle applications or when approaching to stop (very low speed) a momentary squeaking/chirping/sputtering sound can be faintly heard coming from either the engine area or under the vehicle (transmission?). It's more audible with windows rolled down and when driving along a sound reflective area (beside a fence or row of cars for example). At low throttle applications it seems to be very faint but consistent with the application of the throttle itself. When coming to a stop it seems to occur around 5-10mph (just prior to the vehicle stopping) and when the transmission bumps in it's lowest gear before, it chirps/sputters for about a second but this one you can reproduce pretty consistently.

A quick search revealed this 'Service Bulletin' (also attached) --> https://static.nhtsa.gov/odi/tsbs/2022/MC-10225749-0001.pdf

The description of the noise seems to match what I am hearing but the conditions seem to vary compared to mine.

Just wanted to know your thoughts, if others are experiencing this, and if you have consulted the dealership on this issue. According to the Bulletin it seems that GM's stance is that "this is normal, we're not fixing it".

 

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[Bowhunt_Kansas]

I have this chirping sound in the exact same conditions...drives me nuts. I would love to hear if/when anyone finds a fix!

 

[Bowhunt_Kansas]

I have this chirping sound in the exact same conditions...drives me nuts. I would love to hear if/when anyone finds a fix!

No idea if this is related, but now today I started my truck (6.2L) and heard a loud clang like a loose bolt hitting metal. Truck all of a sudden runs really rough and is showing just about all the service messages I can think of. When driving I hear the clang sound over and over. Only 20k miles so needless to say it's in for warranty work on whatever happened.

 

[Maduro8]

No idea if this is related, but now today I started my truck (6.2L) and heard a loud clang like a loose bolt hitting metal. Truck all of a sudden runs really rough and is showing just about all the service messages I can think of. When driving I hear the clang sound over and over. Only 20k miles so needless to say it's in for warranty work on whatever happened.

Doesn't sound related.

 

[slythetove]

No idea if this is related, but now today I started my truck (6.2L) and heard a loud clang like a loose bolt hitting metal. Truck all of a sudden runs really rough and is showing just about all the service messages I can think of. When driving I hear the clang sound over and over. Only 20k miles so needless to say it's in for warranty work on whatever happened.

Sounds like you may have dropped a lifter. This is a known issue on the 6.2 L V8. Hope you get it resolved whatever it turns out to be!

 

[ShapeShifter]

Just seeing this now after posting over here: https://www.at4forum.com/threads/21...tling-noise-when-slowing-down….357/post-16378

This service bulletin described my issue to a T! Right down to the exact speed (14mph) when the issue occurs. I can't believe they are calling this normal though. Pulling timing (by an appropriate amount) shouldn't cause your engine to sound like a tin can being thrown down the stairs. My dealer has not discovered this bulletin yet and tomorrow they are scheduled to spend some time diagnosing it. I wonder what they'll come up with... yesterday they replaced a belt and tensioner thinking that would solve the problem.

Video of my "normal" behavior in action:

 

[Brembo6point2]

Just seeing this now after posting over here: https://www.at4forum.com/threads/21-at4-metallic-clinking-rattling-noise-when-slowing-down….357/post-16378

This service bulletin described my issue to a T! Right down to the exact speed (14mph) when the issue occurs. I can't believe they are calling this normal though. Pulling timing (by an appropriate amount) shouldn't cause your engine to sound like a tin can being thrown down the stairs. My dealer has not discovered this bulletin yet and tomorrow they are scheduled to spend some time diagnosing it. I wonder what they'll come up with... yesterday they replaced a belt and tensioner thinking that would solve the problem.

Video of my "normal" behavior in action:

OMG Mine did this, ended up being idler pulley, was replaced under warranty, but it still does it sometimes when I forget to turn start stop off.

 

[Bowhunt_Kansas]

Sounds like you may have dropped a lifter. This is a known issue on the 6.2 L V8. Hope you get it resolved whatever it turns out to be!

Turned out to be failed crank bearings. Requires a new engine....which is on back order

 

[slythetove]

Turned out to be failed crank bearings. Requires a new engine....which is on back order

Sorry to hear that. Definitely want a new engine but the wait will be difficult. Are they at least putting you in a rental or something in the meantime?

 

[Bowhunt_Kansas]

Sorry to hear that. Definitely want a new engine but the wait will be difficult. Are they at least putting you in a rental or something in the meantime?

They offered me a Chevy Spark.....yay.

 

[slythetove]

They offered me a Chevy Spark.....yay.

That sounds about right.

 

[Armando]

Just seeing this now after posting over here: https://www.at4forum.com/threads/21-at4-metallic-clinking-rattling-noise-when-slowing-down….357/post-16378

This service bulletin described my issue to a T! Right down to the exact speed (14mph) when the issue occurs. I can't believe they are calling this normal though. Pulling timing (by an appropriate amount) shouldn't cause your engine to sound like a tin can being thrown down the stairs. My dealer has not discovered this bulletin yet and tomorrow they are scheduled to spend some time diagnosing it. I wonder what they'll come up with... yesterday they replaced a belt and tensioner thinking that would solve the problem.

Video of my "normal" behavior in action:

Have you figure out the issue? Mine is doing the same and its crazy that a brand new car does this kind of sound

 

[Maduro8]

Just seeing this now after posting over here: https://www.at4forum.com/threads/21-at4-metallic-clinking-rattling-noise-when-slowing-down….357/post-16378

This service bulletin described my issue to a T! Right down to the exact speed (14mph) when the issue occurs. I can't believe they are calling this normal though. Pulling timing (by an appropriate amount) shouldn't cause your engine to sound like a tin can being thrown down the stairs. My dealer has not discovered this bulletin yet and tomorrow they are scheduled to spend some time diagnosing it. I wonder what they'll come up with... yesterday they replaced a belt and tensioner thinking that would solve the problem.

Video of my "normal" behavior in action:

What was your result with the dealer and service? You said they hadn't discovered this bulletin. Was it fixed?

 

[ShapeShifter]

They never did anything. I might try again.