2014 GMC Sierra 5.3L Squeak on Downshift

[Reegs941]

Video (3 second mark for a split second) - I have heard this sound for a while now.  It only occurs during downshifts and I’ve pin pointed that it’s around 43mph when I punch it.  Doesn’t have to be completely floored but likely dropping from 5th to 3rd is my guess?

 

Not sure if it’s a belt slipping or god forbid my torque converter.  Already had to remanufacture the transmission 15k miles ago with new torque converter, shift kit, bypass valve, etc.

 

Just recently had the entire engine rebuilt with a DOD delete, BTR Cam/springs, new Mahle pistons, k&n intake, injectors, rehoned/cleaned, muffler/flap delete and a Diablew tune. This sound occurred prior to all of this.

 

Thanks in advance!

 

 

Edited April 10 by Reegs941

[Reegs941]

Bump?

[daven8844x]

Hi there, did you figure this out?  I have the exact same noise on my truck.  Just started at 80K miles.  2014 GMC Sierra 1500 LT 4X4 5.3L.  Let me know.  Thanks!