When in 2WD and driving at any speed or turning, or in reverse, the drive train is quiet and smooth.
When in 4WD and driving at any speed, straight..or in reverse straight, the drive train is quiet and smooth.
When in 4WD and turning right of left on any surface, at normal 4WD operating speeds there is a strange sound like crunching, sometimes metallic. There is no play in the drive train nor slack in the steering linkages or box.
I am beginning to fear that the front diff. is hosed up. But I would think I would hear the sound all the time since it does turn (free wheel) in 2WD. Why wouldn't this occur when driving in a straight line?
I wanted to get your opinions before I embark on a tear down.
I'm gonna say u-joints. You might not feel anything wrong with them by hand, but after you replace they are quiet. I've seen u-joints so tightly stuck you could not turn then by hand when you removed the axle shafts. But believe me, they make a horrible noise while driving
Spider gears are another possibility, but I'd start with u-joints...
This may be a silly question... but are you trying 4wd on dry pavement?
98 Cherokee Sport- 4.5", AA SYE and TW Shaft, 33" Cooper Discoverer STTs, XCr8000, Jcroffroad Stage 2 Winch Bumper , 60" Hi-lift, Cobra Ultra III, Gragar Soft 8s, Detour Tail Bone, jcr Offroad Stage 2 Sliders, RockCrusher Diff Covers Front, Lockright in the front, Aussie in the Rear (Ford 8.8) with 488s... More $$$ for Bank Account (On Back Order...)
99 Cherokee Sport- Stock and Staying that Way (Wife's DD)
Even if he tries part time 4wd on dry pavement, it shouldn't make any "horrible" noises when turning if everything is fine. Nothing wrong in trying part time 4wd on dry pavement. It's the long-time use on dry pavement and higher speeds that will kill the drivetrain.