AX-15 Failure?

[AeroNautical]

     I'm getting a metallic grinding noise in colder outside temperatures (40 and below), I believe is coming from my AX-15. Shifting is unaffected, no vibrations, bolts are tight, checked all driveshafts to see if they may be rubbing on something. The kicker is, when I first bought the truck, it made this noise around the same temp, with the stock 4.0 and tranny, 2wd. Now, since I've swapped the engine, tranny, added a transfer case, new front and rear axles and driveshafts, the noise is still here.

 

     It's unaffected by the clutch or RPM of the engine. Engine could be off, but with forward momentum, the noise will continue, even in neutral, so that eliminates the front portion of the AX-15 that spins with the engine. 45 and above temps eliminate the noise entirely, but if the temp stays 40 and below, regardless of how warm the drivetrain gets, the sound continues. 

 

     It's pretty frustrating not having a real idea as to what is wrong. Has anyone had this experience before? I'll try to record the sound and upload it next chance I get. Tracking down a noise over the internet is damn near impossible, too, but maybe explaining the circumstances a little might help out. Thanks. 

[teamsmith]

Sounds like a front wheel bearing. I had one that was bad and it sounded like two pieces of sheet metal grinding together. I replaced only the front hubs and sound went away. There's also a chance it could be your front pinion bearing but mine made more of a whaling noise and would only make it above about 30mph. The wheel bearing grind was at about any speed

[AeroNautical]

That's a good heads up, I'll see if I can recreate it with one wheel in the air. Speed doesn't affect it, though. Just temperature. 

[teamsmith]

I could not recreate it with a wheel in the air but I could make it worse by driving and turning the wheel in a curve where more weight was put on one wheel.

[AeroNautical]

I recorded the sound as best as I could:

 

https://youtu.be/VZs6kZ8Jyhc

[64 Cheyenne]

Narrate a little? "Start out, first gear, second"....or where in video, second wise, where you hear the sound?

[AeroNautical]

Trying to do 10 things at once, I kind of rushed the recording. Sorry. I got up to third, but gear doesn't matter. It sounds like it's coming from the transmission tunnel, but sounds are deceiving. The sound is almost constant through the entire video, that metallic scraping sound. The microphone was in the cupholder in my center console.

[teamsmith]

Is it that kind of gurble gurble sound? Assuming your front axle is solid and not CAD, how about dropping your front drive shaft to eliminate the pinion bearings? 

[AeroNautical]

The sound is in the "video" above, not a gurble, but a scraping sound. Turning doesn't affect the sound, either. I recorded it this morning when it was chilly, but this afternoon it didn't make any noise at all because it was about 65 degrees. THAT's what confuses me. 

[teamsmith]

I listened to the video, I was hearing more of a gurble sound. It is a head scratcher that it persisted after you swapped out your drive line.

[AeroNautical]

Which is why I think you might be right about the hubs or something similar. I can't even trial and error it right now because it's too warm outside, it's not making the sound. 

[teamsmith]

You could jack up each side and grab the tire, try to enduce 'play' in the bearing. If it's making that kind of racket, you might be able to feel bearing play. just a thought.