2018 Yukon Denali grinding/knocking noise

[Engineered]

Thank you, will check them asap.

 

[ivin74]

Yes coasting down hill. It is not a humming/gear noise. I would equate it to a badly warped rotor noise.

The exhaust flange is right below the driver floor board, it wouldn't hurt to check and see if the gasket blew out.

 

[ivin74]

One thing I neglected to mention is the front diff mounts. Bushings should be checked.

^x2

 

[Engineered]

Thank you. Making a list for this weekend.

 

[Engineered]

Reporting back. Went under the truck and tried to pry on the rack and diff mounts. Retorqued. All seem tight. Noise still there.

While I was under there I grabbed the stub shaft that connects to the CV Axles. The stub shaft on passenger side has a small amount of in and out movement and no up down left right movement. The drivers side has the same in and out movement, but also has a couple millimeters or about an 1/16th to an 1/8th of up down left right movement.

Thoughts on this?
Thank you

 

[Geotrash]

Reporting back. Went under the truck and tried to pry on the rack and diff mounts. Retorqued. All seem tight. Noise still there.

While I was under there I grabbed the stub shaft that connects to the CV Axles. The stub shaft on passenger side has a small amount of in and out movement and no up down left right movement. The drivers side has the same in and out movement, but also has a couple millimeters or about an 1/16th to an 1/8th of up down left right movement.

Thoughts on this?
Thank you

That's quite a bit of play in the bearing. Should be tight with no up/down movement. Slight in and out movement is okay. Hard to say if that's enough play to be your problem, but it does tell me that you have a worn bearing on that side of your diff that should be replaced anyway. You can do it on the bench, but for differential work on these trucks, I like to take it to a shop because I'm getting old and lazy.

 

[Engineered]

Thank you, I’m going to swap out the bearing and seal. Cheap enough.

 

[Engineered]

Solved. It turned out to be the differential mounting bracket bushings. Decided to replace them as a Hail Mary pass as the bushings looked fine. In addition to fixing the noise described earlier, it also fixed my driveline clunk coming to a stop and accelerating.