2017 Silverado 2500HD Constant Whistle Sound Over 15mph

[Wolfmansbrudda]

Hey all. Been a long while since I've posted in here. I just bought a 2017 Chevy Silverado 2500HD WT 4x4 with the 6.0L engine. Crew cab longbed. It has this annoying (but not super loud) whistling noise that starts between 15-20mph and remains constant at all speeds above. It doesn't ever seem to change in pitch or volume and seems to be coming from the front end...but I'm not sure. I cannot duplicate the sound while standing still. Revving the motor in "Park" makes no whistling noise. The noise only occurs while in forward motion above 15mph.

It was recently in the shop for a tranny fluid change and I asked them to diagnose it. They came up empty and everything in and around the area of the front wheels checked out. Here are some details.

 

• Gaining speed (past 15-20mph) once whistling has started...has no effect on it
• Braking...has no effect on it
• Turning corners...has no effect on it
• Switching in and out of 4H (4WD)...has no effect on it
• Putting the transmission in neutral while driving...has no effect on it
• Letting my foot off the gas...has no effect on it
• Pressing the gas to accelerate...has no effect on it

 

Please let me know what I should be looking for here. I originally thought maybe it was a wheel bearing but after the shop found nothing (and considering the bullet points above) I'm thinking some kind of wind noise?
 

[cfell]

Ours seems to do similar.. check the door gaskets for wrinkles.. slam strips of paper in a few places.. should have some resistance..

[Wolfmansbrudda]

I'm going to try driving with different doors open, covering up bumper openings, etc. to try and isolate the sound.

[Naughty Donkey Performance]

try folding in the towing mirrors, I had one with a chrome aftermarket cover on it that was a MF'er to figure out what the sound was.

Bug shield?

[Wolfmansbrudda]

No bug shield. I do have tow mirrors. They don't have chrome covers.

I did some testing this evening. Rolled all the windows down and that didn't change anything. But I decided to run it up to 15-20mph in reverse, and the whistle still happened in reverse...*groan* So now I'm thinking that it's very likely not wind noise?

I feel like my noise may have a loose connection with engine speed/rpm, but it's hard to detect. I drove down a long hill, put it in neutral, and I feel like the noise got slightly quieter as the rpms went down while I was coasting.

I thought that maybe when I got home I'd spray some belt dressing on the belts, so I did that...but no change.

I feel like I can possibly hear the/a whistle/squeal ever so slightly when idling, but when I rev the engine in Park in my driveway it still won't get any louder.

Edited July 13, 2023 by Wolfmansbrudda

[mjm-1957]

Put it on a floor jack and slowly run it until the noise starts. I am a GMC Buick line mechanic and have seen this before, The transfer case output shaft seal will whistle where it rides on the slip yoke. Remove the rear shaft and grease the yoke and retest, If the noise goes away then replace the output seal in the transfercase.

 

 

 

 

 

 

 

[Wolfmansbrudda]

I did some more testing to try and isolate the sound. I jacked it up in the rear, chocked the front tires, put it in drive (only rear tires spinning) and the noise started. I assume I can now rule out wind noise and the front driveline. This seems so far to be pointing to your guess Mike as to it being in that driveshaft seal. So I'm guessing checking that will be the next step.

[Wolfmansbrudda]

It's been awhile but I wanted to post an update. Whistling is finally fixed. I localized the sound to the rear differential. A new differential bearing kit took care of it.