Engine Chirp, Squeak or Ping

[prstaples]

Hi All,

 

I have a 2015 Sierra with the 6.2/8-speed combo that I love. It has about 4500 miles on it. Shortly after my first tow experience with a camper at 2000 miles the engine started to squeak or chirp. It starts around 1200 RPM and then dies off before the next shift point. Then it starts again. It happens at all speeds, particularly on the highway while in higher gears. It is not the exhaust flapper valve as I have a Corsa cat back exhaust that sounds great. It makes the same, but more subdued sound when revving the engine in Park or Neutral. It does not make the noise when coasting or slowing down so I assume it is valve train (lifter?), AFM or exhaust related. I bought an AFM disabler (not currently mounted) and it still made the noise. It comes from directly in front of the driver, possibly behind or just below the firewall.

 

I have been to two separate dealers. One hears it, the other cannot replicate it. The one that hears it says nothing appears wrong so they will not pursue it further. This is fine until something fails with a 7000 lb trailer on the hitch in the middle of Missouri.

 

Does anyone any any experience with this kind of noise? Here are some videos. Crank the volume and listen for a squeak or pinging sound.

 

Thanks!!!

 

https://www.youtube.com/channel/UCY3JvgK15Ff7dNkfOUJDXGg