I have a 2014 GMC Sierra 1500 SLT double cab with the 6.2L. Recently noticed a hollow sounding metallic rattle. Almost like a vibrating heat shield. It is very hard to reproduce; however most commonly occurs after truck has been running for some time and goes from 0-30 mph. If you let off the gas when it’s occurring it will stop but usually only last for a couple seconds anyways.

I’ve checked all my heat shielding, U joints, exhaust mounts, and other obvious things you could just by getting under there and inspecting things. Differentials should be good; I changed oil and inspect a few thousand ago. Popped the 3/4 socket plug out and stuck finger in and still nice and golden without a bunch of shavings. My only guess could be a catalytic converter perhaps that when heated will rattle some? The truck still drives great no slipping of gears or loss of power when this sound occurs.

VIDEO OF SOUND:

 

Hey Nick did you ever find the source of the rattle in your Sierra? I am experiencing the same issue and searching for answers. Any input is much appreciated. Thanks

 

I have been having this same noise for over a year. I should take it in, but I dont want to spend hundreds to troubleshoot it. Please tell me someone found out something on this. Mine sounds just like this.

 

Have you figured anything out?

 

I added a tube of shutter fix to the transmission fluid. It worked immediatly. I havent had any issues. Everything is nice and quiet.

 

Nick, I have the same rattle. I've had various exhaust pieces removed and replaced by pipe: flex joint, small converter, and the flap door behind the muffler. No luck. Did you find a fix for yours?