help identify this noise

[DHGFX4]

Not sure weather to post this under transmission, transfer case, or engine section of the forum.. but here goes lol.

Noise has been coming and going. I replaced the CV axle.. thinking that was the problem. Apparently not as the sound is still there. Ive noticed the noise quiets down, almost silent after driving for a while.. maybe 5-10 miles. It almost sounds like a jack hammer in the distance. The video is of me pulling out of a parking lot. Sorry, dont know how to embed videos.

A buddy of mine said he believes its a "ball style joint" behind the u-joint yoke on the transfercase side.. so im assuming that is what's underneath the rubber boot on the front output side of the transfercase.. its on an OBS Z71 with Autotrac.. so NP246 i believe.

Vid: https://www.facebook.com/photo.php?v=773941165967767&l=5877455817716733671

 

[highspeed]

I have heard transfer cases make similar noises. Its almost like your transfer case is partially engaged. Do you feel any vibration?

 

[DHGFX4]

No vibrations..

 

[highspeed]

Push button 4x4 I assume? Make sure its working completely and disengaging like it should.

Just in case, check for play in the driveshafts front and rear. But it sounds like it you have an internal t-case problem. It your t-case is a floor shift, make sure it is completely disengaged.

If everything looks good, jack that thing up and put it in drive with the wheels off the ground, but don't get the wheels spinning too fast, its not good for the driveline. And be careful as well.

 

[DHGFX4]

Yes, its push button with Autotrac.

Will have to try and jack it up and run it.. but heres my dilemma

In my diagnosis, the noise goes away when engaged in 4x4. The noise is coming from the front.. so Im not sure how im going to get the front wheels to spin in the air in 2wd, since the noise goes away when engaged in 4x4. (All three modes at that; auto, 4hi, 4lo.)

I had the front in the air when I replaced the CV axle last week. I spun the tires, and no odd noise was present.

I checked the front driveshaft. Seems to have some play, but not sure how much is too much. U joints seem tight.

On the way to work this morning, it didnt make a single peep.. so the noise comes and goes at random.

The transfer case was also replaced a couple years ago by the previous owner, for unknown reasons.

 

[highspeed]

Hmmm, I guess you will just need to keep track of the "conditions" to see when it happens and then see if you can recreate it. When you say it is coming from the front, do you mean the front diff area? It can be hard to pinpoint an issue like this because the sound reflects so many different ways underneath. Im gonna listen to your clip again and see if anything else comes to mind.

 

[highspeed]

Listened to it 3 more times. It almost sounds like a bad cv axle. Does the knocking change with rpm or speed?

 

[DHGFX4]

Yes its definitely rotational in nature as it changes with speed. I just changed out the axle last week with a napa unit.

 

[highspeed]

could be a faulty cv axle, never know with reman'd or aftermarket axles. I have had 3 "new" ones be defective on other vehicles

 

[ShadowRejects]

Only time my truck has knocked was when the wheel was loose in the front and another time when i shattered my CV axle shaft. Try taking out your actuator and see if its partially engaged or not. It would be pushing against the diff slightly causing a knock