my wife's JKU has been making strange noise in 4x4. I check all the u-joints and they look fine. I thought it sounded like the gears were damaged, but I popped the cover today and they look just fine. it's a tick tick tick sound that is rotational (increases with speed), only in 4x4 (low or high, but can be heard best in high), and only with torque. the video isn't great, but you can hear it a little.
Untitled by Jay Carlson, on Flickr
any thoughts? 4x4 seems to work just fine and there's no big pops or jumps like a stretched t-case chain would produce. so I'm a little at a loss. the only thing I can think of is that the joint where the front drive shaft connects to the t-case is old. the Jeep is a 2017 w/90k on the clock. all original drive train parts.