Silverado 18 Z71 grinding/ slight vibrating noise

[Silverado85]

I have a 18 Silverado that I got about 2 months ago. It makes a grinding ( almost like a vibration noise) when slightly accelerated, usually when coasting at highway speeds. It almost feels like whenever you go through rumble strips on the ground but not as intense. It is a momentarily sound, then it goes away as the truck accelerates. It only does it in some instances. It seems like it happens when it shifts from V4 to V8. I tried the manual shift and put it in 5th gear so the AFM would not activate and It seems like the noise goes away.  Has anyone experienced this on their Silverado? Any help or guidance as to what could cause this would be greatly appreciated.

[cr250Silverado]

Idk for sure but I have read about others torque converters going out and they desricbe the same “rumble strip” thing as you. It seems our torque converters commonly fail even on new trucks. Take it in and ask them to check out the torque converter. 

[Silverado85]

Sorry, I forgot to mention I did take it and they did consider the torque converter. The tech and I went on a ride and according to him, the torque converter does do something similar but he said it would be felt a lot more.  Again, that’s what he told me. But I might have to take it in for a second opinion. 

[B R A D]

My '16 Sierra had this problem. The next time it happens watch your RPMs, they will probably be bouncing around. They flushed mine and it fixed it for around 8k miles and it came back. I traded it off but its frustrating to hear that GM has known about these problems for a few years and keeps putting the same junk in.

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[Silverado85]

Yeah. At this point, I don’t know how serious the problem is but it’s more of the frustration. It sucks listening to that noise. Thanks a lot for the info

[B R A D]

Also, it gets progressively worse. I made a video of mine with a gopro and you could clearly watch the steering wheel bounce, even with video stabilization turned on.

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