When you select Auto4x4, the t-case clutches start to engage and a small amount of torque is sent forward (maybe 5%). When rear wheel slippage is detected, the clutches fully engage, splitting the torque font and rear.

Sounds like you have more than "stand by" clutch engagement. One of the internal bearings has been know to fail, perhaps that is your problem.

If the noise is coming from the front, perhaps a bad bearing in the front diff.

 

Interesting. The noise in 2wd from the front (or seemingly from the front) is mostly noticeable at around 50 mph+. If I'm cruising along at a steady 50-55 mph and hit the auto button, the noise goes away. :eyes:

 

does the sound come from the drivers side?

 

does the sound come from the drivers side?

Seems to be. Can sorta feel it through the floorboards when it's being really loud.

 

I would take it to a ring and pinion shop.Most will check it out for free. I had a bad driverside bearing in my front diff. it made the same noise.

 

I made a right hand turn after stopping and the drive-line binded up so bad, it was almost enough to stop the truck mid-turn!. It felt more like it was in 4wd high rather than auto mode.

Check the t-case fluid. I had similar symptoms when I first bought my '98. Checked the fluid and it was pink, indicating someone had used Dex III rather than the blue AT2 fluid that it is supposed to use. Drain and refill with the correct fluid and it stopped binding up.

I don't know if it stayed the same, but the fill plug on my tcase is a square 5/16" drive plug. I ended up buying a 3/8 socket adapter and grinding it down to 5/16 so it would fit.

 

I would take it to a ring and pinion shop.Most will check it out for free. I had a bad driverside bearing in my front diff. it made the same noise.

Yeah, it may come to that. Just afraid its going to turn into an endless (and expensive) quest to fix the problem and still not succeed. I've read enough stories online of that happening to people with similar problems, which is why I've delayed fixing it for so long. Sorta testing the waters on getting a 2013 right now. It has some other issues, including totally rotted out rocker panels, and I'm not sure I want to dump thousands into a 13 year old truck. Stay tuned.

Check the t-case fluid. I had similar symptoms when I first bought my '98. Checked the fluid and it was pink, indicating someone had used Dex III rather than the blue AT2 fluid that it is supposed to use. Drain and refill with the correct fluid and it stopped binding up.

I don't know if it stayed the same, but the fill plug on my tcase is a square 5/16" drive plug. I ended up buying a 3/8 socket adapter and grinding it down to 5/16 so it would fit.

I changed it a couple years ago and the proper stuff was in there. Checked it awhile ago and its still full.

 

i thought auto 4x4 worked by leaving the front diff engauged (right axle shaft locked together) and then the trasfcase was 4x4/4x2 engaged as nessary? i belive if your front diff is engauged rather its 4x4 or 4x2 you will get the binding action.

 

i thought auto 4x4 worked by leaving the front diff engauged (right axle shaft locked together) and then the trasfcase was 4x4/4x2 engaged as nessary? i belive if your front diff is engauged rather its 4x4 or 4x2 you will get the binding action.

I think I follow what your saying, and yes, in any of the 4WD positions, the front axle is engaged. Maybe using the AWD only trucks may be easier to follow.

The trucks that only have AWD, do not have the passenger axle disconnect, both axles are connected to the front diff at all times.

Although the front diff is an open diff, both axles connected to the diff will cause the front driveshaft to turn. As the front wheels turn in two different radius, which is also different than the rear turning radius, the front and rear driveshafts will turn at different rpms; therefore, internal t-case slippage is necessary to prevent binding.

 

After thinking about It I'd like tj take the last half of my statement back haha. So the only way to get the bind is by having the transfer case engaged right?

 

You will get a bind if the t-case clutches are engaged on a dry/hard surface. However, it could be coming from other places.
If the truck has a locking/posi rear end and the clutches/locking pawl are engaged, the rear end will bind (crow hop) on a turn; but, the binding won't be as noticeable. The front diff could have some broken pieces, causing binding, but switching into, and out of, 4WD should not change it.

From the description, I'm thinking t-case clutches. Some times, a fluid change will cure it.