Sonny James

I am wondering if the folks that have commented on this post can add another post stating their make, model, and trim. The reason I say this is becuase I wonder if the noise is more noticeable on certain makes such as a Chevrolet 3500 LT, or LTZ or GMC SL or SLT than say a Chevrolet High Country or GMC Denali or 2500HDs. I currently have a 2020 3500HD Denali that definitely makes the noise. The noise became louder around 500 miles. But other than when I first start it, I don't hear the noise once I start driving. I do however have another noise that is prevalent at 1550 RPM. The dealer is getting ready to swap with me for another 3500HD Denali ( last 6 of VIN 30 numbers lower than my current truck) that doesn't make the noise. I will report back on the other Denali truck as to whether there is a loud clunking noise coming from inside the cab.

I have the same what I call "clunking" noise in my 3500HD Denali that got a little louder after putting 500 miles on it. It is for sure noticeable when standing outside the truck. The good news is that it's very faint in the cab and as it warms up it pretty much goes away inside the cab. Especially with the radio going. So if you no longer hear the noise in the cab, especially after warming up, I would say this is something everyone else has versus being an excessive noise.

Hi MTU Alum, since you work for GM I'd like to ask if you know about a problem I am having with my 2020 Siera Denali 3500HD Diesel hat seems transmission related. The first time I went over 70 MPH (after 500 mile break in), I noticed a loud vibration noise. I have learned I can reproduce this issue by finding a gear that will put the truck at 1600 RPM. This includes driving at 73-75 MPH in 10th gear, 68 MPH in 9th Gear, and around 54 MPH in 8th. The more I drive it the more I hear it when shifting through lower gears as the tach reaches 1600 RPM. The noise is like a load howling/cowling noise. Passengers report feeling a vibration coming out of the floor. It's been at the dealer over a week and a half. They had a GM engineer that worked on it for 4.5 hours. He said it wasn't transmission and spent the majority of his time around the intake from what I understand. He had monitors and sensors all over the place and at one point thought he had it fixed. Then when road testing the noise came back. Now I am being asked to talk with a GM district manager. I am also told the dealer found another truck making the same noise. I know they are going to say this is normal. But when I started this process with the dealer, I drove a truck that is 30 VIN numbers less than mine from their lot and it did not have this issue. Rides beautifully. There was one point in time where I was promised that I would receive a new transmission until the GM showed up. They also tried a bolt fix under Bulletin #19-NA-216 with no help. Any insights that you have into this would be much appreciated.

I have a 2020 3500HD Duramax Diesel Denali and think I have a transmission issue at just over 500 miles. The first time I went up to 74MPH I heard a hollow howling type noise that seemed to come from the front right of the truck. My passenger stated he thought he felt the floor vibrating and it sounded like it was coming from the rear. What I have learned is if I put the transmission in manual shift, then do 74, I hear the noise in 10th gear. If I downshift from 10th to 9th the noise goes away. If while in 9th gear I slow down to 68, the noise comes back until I downshift into 8th. When hearing this noise, both times the tach was exactly at 1500RPM. Also, when accelerating if I hear the noise at lower speeds and look at the tach, it is at 1500RPM. Anyone else having this issue?

So I have what appears to be a transmission issue at just over 500 miles. The first time I went up to 74MPH I heard a hollow howling type noise that seemed to come from the front right of the truck. My passenger stated he thought he felt the floor vibrating and it sounded like it was coming from the rear. What I have learned is if I put the transmission in manual shift, then do 74, I hear the noise in 10th gear. If I downshift from 10th to 9th the noise goes away. If while in 9th gear I slow down to 68, the noise comes back until I downshift into 8th. When hearing this noise, both times the tach was exactly at 1500RPM. Also, at times of acceleration if I've heard the noise at lower speeds and when looking at the tach, it is at 1500RPM. Anyone else having this issue?

I put 550 miles on my new 3500HD Denali yesterday. When picking it up new at 45 miles, there was a faint thumping/clunking noise. After putting 550 miles on it is more noticeable when standing outside the truck. So far I don't hear it in the cabin especially with the stereo going. I do have another issue that I will post separately that I believe it is an issue with the transmission. Here is a snippet if anyone else wants to comment: When doing 73-75 miles per hour I hear a hollow howling type noise that seems to come from the front right of the truck. My passenger stated he thought he felt the floor vibrating and it sounded like it was coming from the rear. What I have learned is if I put the transmission in manual shift, when doing 74 and then downshift from 10th to 9th the noise goes away. If while in 9th gear I slow down to 68, the noise comes back until I downshift into 8th. When hearing this noise the tach is exactly at 1500RPM. Also, at times of acceleration if I hear the noise at lower speeds and look at the tach it is at 1500RPM. I believe for every gear, if there is a speed that is hit that puts the engine at 1500RPM, I will hear the noise. Crazy!!

I test drove a lot of 2500HD and 3500HDs since 12/2019. Some had the same level of noise as in Redwingr's video. I just bought one that has a much quieter version of his (at temperature - 180 degrees) with 50 miles (mostly put on by me). I am hoping it won't get louder by 500 miles like everyone is reporting. I warned the dealer I will be coming back if it does. I am taking a video when I pick it up in case I need to show the dealer before and after noise if necessary. Will give everyone an update at 500 miles.

Also have noticed when driving around 35-40 mph at around 2K rpm there is a distinct whining noise.

I'm test driving 2020 3500HD Denali's now. I have a 2017 2500HD Denali currently which for sure does not make this noise. I've test driven (5) 3500s and (1) 2500. Two of the 3500s and the 1 2500 have made this noise, so 3 out of 6. They all have less than 30 miles on them. The 3 trucks that made the noise did so after I pulled into a parking lot and threw them into park. They continued making the noise at low idle during the remainder of the drive. I don't remember the 3 others making the noise but I also drove them without pulling over and putting them into park. Not sure of the correlation here but Bass Mechanic has nailed the noise in his video. I am going to drive a couple 3500s again that I drove before the 3500 that makes the noise and put them through a rigorous set of tests to see if I can get them to make the noise as well. I will report back. Should be this Monday.