2015 gmc sierra denali 6.2l - grinding noise front end

[Adoomie Abdallah]

This grinding noise comes and goes randomly. Sounds like it's coming from directly under the dash but kind of more on the drivers side (maybe because i only hear it while driving and Im on that side) It doesn't happen when I'm idle, I believe it's something in the drive train. It only happens when there's a load/tension on the drive train. It's not a constant sound but very often and I can't recreate the sound by turning or certain RPM's or anything, just comes and goes. The sound can also be a lot louder and rougher at times and sometimes a more subtle sound. Sounds like gears or splines grinding. When I hear it, I let go of the gas petal and press it again and it will go away. Cycled through all 4x4 options, makes no difference. I checked drive shafts and they seem pretty solid, nothing else obvious. Transmission is solid as well. I was thinking maybe transfercase but I'm not too sure.

 

Any help or ideas please? Thanks

[rav3]

How many miles on your truck? Have you done any fluid changes/maintenance? 

[Adoomie Abdallah]

Currently has 180xxxkm (111xxxmiles)

I bought the truck last year at 160xxx and it's been making that noise the whole time. I also had the engine rebuilt at 170xxx due to a lifter collapsing/breaking apart and scoring my camshaft. But before and after the rebuild the noise is still the same. Transmission fluid was also replaced during the engine rebuild.

[BO TIE 1]

Have you looked at the brakes? I had to do brakes on my 2018 Silverado at 34,000 miles due to the inner pads on all four wheels being down to metal. The outer pads were in good condition. I wouldn't have seen it without doing a deep inspection. 

[Adoomie Abdallah]

Yes just did all of my brakes and rotors

 

[mikeyk101]

Did you use OEM or aftermarket brakes and rotors?

[Adoomie Abdallah]

Straight from my local gm dealer. 

[Buckwild27]

It's not something as simple as a bent backing plate or a heat shield is it? 

[Adoomie Abdallah]

No I'm 99% sure it's in the drive train just don't know how to diagnose transfer case or diff or cv axle without opening everything up 

[rav3]

The easiest thing to do is to drain the transfer case & the front differential and see what kind of debris is in there or not.

[BO TIE 1]

You can try and disconnect the front drive shaft and drive it and see if noise stops. 

[Adoomie Abdallah]

On 6/6/2024 at 10:38 AM, BO TIE 1 said:

You can try and disconnect the front drive shaft and drive it and see if noise stops. 

I'll try this today or tomorrow. If the sound goes away, I can assume it's the differential?

[Adoomie Abdallah]

On 6/6/2024 at 10:32 AM, rav3 said:

The easiest thing to do is to drain the transfer case & the front differential and see what kind of debris is in there or not.

I'll drain fluid after I test removing front drive axle 

[Adoomie Abdallah]

Update: removed front drive shaft, test drive gives me same noise. 

Removed rear drive shaft, took for a drive and noise is gone. Mechanic friend told me most likely bearings in rear diff. Took it apart, all bearings looked fine and gears etc all tested good and within spec, but replaced bearings anyways. 

 

Just finished test drive, same sound

 

Could it be a unbalanced drive shaft? Or am I looking at transfer case issue? Any help is much appreciated thank you

[BO TIE 1]

How are the U joints?