Bailey’s 6.2

Ok the whistle is gone !!! They have resolved the issue with part #84626475 Hose 3.120 Y Its a vent hose on the gas tank that was to small. It collapses upon itself and whistled.

Update the dealer just called me they found the problem late last night. It’s a emissions valve!! GM aperantly knows about it and had not told the local dealers yet. They have ordered the replacement part it will be here Monday morning!! I will let you all know if this really fixes the problem next week when I pick it up

I took my truck to the dealer yesterday. The foreman and I took a cruise replicated the noise. If I drive for a few minutes and shut the truck off, we can hear a faint whistle from the fuel tank. They kept the truck and have good direction to go. He believes it’s a pressure balance issue with the fuel tank. Their customer service has been fantastic at my local dealer!!! I will let you all know if they find a solution today!!

Ok so I have tried everything listed so far air on or off vent open closed. Stereo on and off. All driving modes and nothing stops the noise windows up down. Tape over the microphones! I can replicate it regularly now which is good. The dealer has had me waiting for a call for weeks. I went in talked to the manger. He said to tell you the truth it could be one month or a year before they figure it out !!! Unexceptable answer. I leaned over and calmly said I got over 80k sitting out there and she whistles at me when I drive it! Your going to need to come up with a better answer! He comes back five minutes later and says the shop foreman will try and drill a hole in the valve covers new PCV set up. They believe it’s the whistle problem. So I scheduled it. The next day he calls me and says GM found the problem. A new valve cover is being shipped out!! Ok so yesterday they put it on instead of drilling a hole in mine. It still whistles !!! WTF GM Iam about to go on a four hour trip for Christmas. Dont really even want to take the truck this sucks. So when I return form vacation. The service manger and the shop foreman have agreed to go for a long ride till some one crawls around and finds it. I will say thier customer service has been very helpful and they are trying. I will not take no wait till we figure it out for an answer!! I would andvise any one going thro this to do the same with their local dealer. I will Let you all know when I schedule the ride next week.

I had the exact same situation. Took it back to the shop. They reinstalled the the flapper on the down stream side of the muffler. Drone problem fixed all is good.

I have the same sound driving me crazy! Iam able to reproduce it around 1700rpm under very easy throttle. This happens every single morning on my way to work. Cruzing between 73-75 mph it’s faint and comes and goes. I went to my dealer took a service tech for a ride he heard it. Said he knows absolutely nothing about the new trucks and was his first time in one. So They have reported it to their engineers and told me to wait for a call back. This was two weeks ago!! I called yesterday they said it could take weeks longer no clue. Really I pay ? for a fully loaded 6.2 Sierra Denali 4x4 brake upgrades etc.. and my dealer tells me I don’t know. Just drive around with a random ringing sound till we call you !! I little help here GM??