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Normal L8T noises?

BuckWallace

By BuckWallace
in 6.6L Gas V8 (L8T)

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Aimatdeer Enthusiast

Aimatdeer

Posted
Posted

I have a 24 since August. If I don't have the radio on lightly accelerating I can barely hear a whine/whir in what seems like 5th and 6th gear. Radio on even low volume can't hear it. Accelerating a little harder doesn't seem to be there. Hopefully normal.

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Another JR
Another JR

Planetary gear sets are particularly noisy because of the sympathetic vibration of multiple gear sets of identical design generating reinforcing noise energy. It’s a common, known issue with helicopte

switters
switters

They did! Sold me a NEW 2024 for only a little more than the pre-owned 2024 I bought with the transmission issue. All's well that ends well! 😀

Byrds8
Byrds8

https://static.nhtsa.gov/odi/tsbs/2024/MC-11012007-0001.pdf   It has a few items on this list but about youre looking for the below portion.   Reaction Gearset Whine (Gearset One)

Graves Enthusiast

Graves

Posted
Posted (edited)

I have a 2024 2500HD 6.6 gas and I am getting the same whining noise, but mine has gotten louder over time, used to only hear at slower speeds just starting out, now it is louder and here it almost all the time, going into the dealer next Monday, see what they say.

 

Edited by Graves
  • 2 months later...
lineman1234 Enthusiast

lineman1234

Posted
Posted

Almost 50,000 on my 2024. No motor noises at all, just smooth. 

 

Same no worse no better transmission sound/s it made from new.

  • Like 1
  • 4 weeks later...
OS RR Enthusiast

OS RR

Posted
Posted (edited)

Aside from a slight wine from the transmission (that's remained constant since new, so I don't worry about it) and to be honest, it could be the power steering pump too. I haven't cared to dig into it.

 

Engine makes some general bottom end "running engine" noise. I pay no attention to it.

 

24 w/ ~16k miles. Daily driven since the day I bought it.

Edited by OS RR
  • 1 month later...
Rickochet Enthusiast

Rickochet

Posted
Posted

My 2026 Silverado 2500 Hd 6.6 Gasser has the same noise.  It is especially prominent at 2,000 RPM's.  Everyone I had ride with me asks, "Wow, that turbo sounds mean!"  It's embarrassing to say, "Sorry, that's not a turbo, because it doesn't have one.  Unfortunately, GM says it's normal transmission noise."  They usually respond with,  "Wow, I'm not buying a GM truck!!"  It's so sad that GM has this attitude on my brand new truck with only 3,000 miles on it, and it made that noise on my test drive and remains today.  I'm at the dealership right now to get it checked again.  I'm also going to drive another new 2500 HD to see if it makes the same noise.

 

PLEASE NOTE:  GM, I am truly disappointed with this type of quality control and customer service.  

  • Like 1
Byrds8 Enthusiast

Byrds8

Posted
Posted

Mine has made the same noise since new. There is a TSB about it. My dealership said the same thing, it's normal. Its generally around 3rd to 4th gear and its gone around 38mph.

Another JR Senior Enthusiast

Another JR

Posted
Posted

Planetary gear sets are particularly noisy because of the sympathetic vibration of multiple gear sets of identical design generating reinforcing noise energy. It’s a common, known issue with helicopter main rotor drive transmissions. However, the designer/builder should be taking comlonly known design measures to minimize the noise. For GM to simply say “normal noise” for a particularly noisy gear set is to ignore the engineering/builder challenge to minimize noise for such gear sets, and indicates laziness and lack of care.  
 

Unfortunately as a consumer all we typically can do is vote with our dollars. As a professional aviation systems analyst with vibration and noise expertise, I have become so disgusted with current automotive manufacturers that the rule I follow is not to buy any product that doesn’t have at least a ten-year track record. We cannot rely on the integrity of manufacturer’s engineering organizations to put out good products, and can only rely on demonstrated reliability. It’s sad, but they asked for it. 

  • Like 4
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Rickochet Enthusiast

Rickochet

Posted
Posted
14 hours ago, Byrds8 said:

Mine has made the same noise since new. There is a TSB about it. My dealership said the same thing, it's normal. Its generally around 3rd to 4th gear and its gone around 38mph.

Do you have the TSB or a link to it? 

Rickochet Enthusiast

Rickochet

Posted
Posted
12 hours ago, Another JR said:

Planetary gear sets are particularly noisy because of the sympathetic vibration of multiple gear sets of identical design generating reinforcing noise energy. It’s a common, known issue with helicopter main rotor drive transmissions. However, the designer/builder should be taking comlonly known design measures to minimize the noise. For GM to simply say “normal noise” for a particularly noisy gear set is to ignore the engineering/builder challenge to minimize noise for such gear sets, and indicates laziness and lack of care.  
 

Unfortunately as a consumer all we typically can do is vote with our dollars. As a professional aviation systems analyst with vibration and noise expertise, I have become so disgusted with current automotive manufacturers that the rule I follow is not to buy any product that doesn’t have at least a ten-year track record. We cannot rely on the integrity of manufacturer’s engineering organizations to put out good products, and can only rely on demonstrated reliability. It’s sad, but they asked for it. 

Another JR, So true, and thanks for sharing your wisdom!  The whine sounds like an old-school radio whine from an aftermarket radio that was installed with a poor ground.  Not something that we should expect from an $80,000+ truck.  I believe that GM monitors these forums, maybe I will receive a call...  Time will tell.

Byrds8 Enthusiast

Byrds8

Posted
Posted
50 minutes ago, Rickochet said:

Do you have the TSB or a link to it? 

https://static.nhtsa.gov/odi/tsbs/2024/MC-11012007-0001.pdf

 

It has a few items on this list but about youre looking for the below portion.

 

Reaction Gearset Whine (Gearset One)

With variation in gear tooth finish and positional control, some customers may experience whine from the reaction

planetary gearset during light to moderate driving conditions.

Most common conditions to hear whine from the reaction gearset is in 4th and 5th gear (20-35 MPH) (32-56 KPH).

Reaction gearset is active in gears 3-6 and 8-10 so depending on severity it may be possible to hear in gears other

than 4/5.

Frequency of whine will change as transmission shifts gears due to component rotation speeds being changed.

Utilizing manual tap to shift through gears is a good way to verify what gears whine in present in.

Note: Whine from the reaction gearset should not be present in 7th gear due to the 1:1 ratio and gears being locked.

If whine is present in 7th gear, issue likely lives with some other component.

  • Like 2
OS RR Enthusiast

OS RR

Posted
Posted
1 hour ago, Byrds8 said:

https://static.nhtsa.gov/odi/tsbs/2024/MC-11012007-0001.pdf

 

It has a few items on this list but about youre looking for the below portion.

 

Reaction Gearset Whine (Gearset One)

With variation in gear tooth finish and positional control, some customers may experience whine from the reaction

planetary gearset during light to moderate driving conditions.

Most common conditions to hear whine from the reaction gearset is in 4th and 5th gear (20-35 MPH) (32-56 KPH).

Reaction gearset is active in gears 3-6 and 8-10 so depending on severity it may be possible to hear in gears other

than 4/5.

Frequency of whine will change as transmission shifts gears due to component rotation speeds being changed.

Utilizing manual tap to shift through gears is a good way to verify what gears whine in present in.

Note: Whine from the reaction gearset should not be present in 7th gear due to the 1:1 ratio and gears being locked.

If whine is present in 7th gear, issue likely lives with some other component.

 

 

Mine has what I think is general pump whine. But also does this, not sure what gear. Sounds like a power steering pump groaning when it shifts. Pretty random as to when it happens. Usually coming down hill and it up shifts.

Rickochet Enthusiast

Rickochet

Posted
Posted
21 hours ago, Byrds8 said:

https://static.nhtsa.gov/odi/tsbs/2024/MC-11012007-0001.pdf

 

It has a few items on this list but about youre looking for the below portion.

 

Reaction Gearset Whine (Gearset One)

With variation in gear tooth finish and positional control, some customers may experience whine from the reaction

planetary gearset during light to moderate driving conditions.

Most common conditions to hear whine from the reaction gearset is in 4th and 5th gear (20-35 MPH) (32-56 KPH).

Reaction gearset is active in gears 3-6 and 8-10 so depending on severity it may be possible to hear in gears other

than 4/5.

Frequency of whine will change as transmission shifts gears due to component rotation speeds being changed.

Utilizing manual tap to shift through gears is a good way to verify what gears whine in present in.

Note: Whine from the reaction gearset should not be present in 7th gear due to the 1:1 ratio and gears being locked.

If whine is present in 7th gear, issue likely lives with some other component.

 

Thanks so much for the information, Byrds8.  I have the noise in Park or while driving, especially loud at 2,000-2,500 RPM.  According to the TSB, the most applicable condition is this one:

 

Park Transmission Oil Pump Gear Mesh Whine Unlike previous generation HD transmissions (6 speed), the 10 speed Allison model transmission utilizes a (3) spur gear design (driven off of the torque converter) to drive the transmission oil pump. Due to the 3–spur gear design, some transmissions may exhibit a whine noise while in park or driving and may get louder as engine speed or transmission temperature increases. Isolating the whine to the oil pump gears can often be done by replicating the complaint in park and sweeping engine speed slowly from base idle to 2500 RPM. If whine can be reproduced in park, replacement of the transmission front support and/or transmission oil pump often corrects the whine complaint.

  • Like 1
Rickochet Enthusiast

Rickochet

Posted
Posted
On 2/17/2026 at 6:34 PM, Byrds8 said:

Mine has made the same noise since new. There is a TSB about it. My dealership said the same thing, it's normal. Its generally around 3rd to 4th gear and its gone around 38mph.

Did you have your noise repaired or just living with it?

Byrds8 Enthusiast

Byrds8

Posted
Posted
1 hour ago, Rickochet said:

Did you have your noise repaired or just living with it?

Since I’ve seen a lot of posts mentioning this noise and GM seems to elude to its normal, I am just leaving it be. If it gets worse with time etc I’ll make them do something. I didn’t want them to swap the transmission out if the next one was going to do the same thing. 

  • Like 1
Pryme Senior Enthusiast

Pryme

Posted
Posted
On 2/18/2026 at 8:32 AM, Rickochet said:

Another JR, So true, and thanks for sharing your wisdom!  The whine sounds like an old-school radio whine from an aftermarket radio that was installed with a poor ground.  Not something that we should expect from an $80,000+ truck.  I believe that GM monitors these forums, maybe I will receive a call...  Time will tell.

Oh man I remember that sound from back in my car audio days. That would drive me up a wall. I don’t think this sound has to do with the 6spd. I’ve never heard it.  Must be 10spd only?

  • Like 1

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