So when I put my XJ into 4WD high, it pulls hard to the right on any terrain. It also gets stuck in 4WD, before it would disengage quickly, now it takes a few miles of driving of pavement to disengage.
I check the diff and tcase fluid levels and they are
all full. What could be causing this?

 

I'm no expert like some people on here but I did a little research and read that it may be in your locker.
Or it may be due to your tire tread.

Just go to google and search 4wd pulling right cherokee

You will find many results. Sorry I'm not an expert.

 

What year is your XJ?

A few thoughts on it pulling right:
1) Check your tire pressures up front to see if the right side is much lower than the left.
2) Check steering box, drag link, and tie rod/tie rod ends for play. If there is slop up front applied power might induce some type of "torque steer" (?)
3) Check your axle U-Joints to see if they are intact and in good shape. You might only be getting power to one side.
4) Following on #3, check to see if your front axle shafts are complete and engaging the differential.
5) Check your differential.

Now, about getting back out of 4WD. What transfer case do you have? I'd start by coming to a full stop, putting it in 2WD, backing up a little, then moving forward. See if that disengages it quicker than, say, a shift on the fly.

 

Here's how to shift the transfer case:

Here's how the factory suggests you shift the transfer case and I've been doing this since these things were new and I worked at the dealership. Quoted from the owner's manual. The suggestions in CAPS are mine.

"To engage, shift the transfer case lever from 2H to 4H while the vehicle is moving at any legal speed". I LET OFF THE GAS, THROW THE LEVER, TAP THE GAS AND LET OFF.

4L position: " To engage, slow the vehicle to 2-3 MPH , shift the transmission to Neutral, then shift the transfer lever to the right and pull firmly rearward to 4L".

TO SHIFT OUT OF 4L, SHIFT THE TRANSMISSION INTO NEUTRAL WITH THE VEHICLE STOPPED, SHIFT THE TRANSFER CASE LEVER TO 2H, THEN THE TRANS TO D IF YOU HAVE AN AUTOMATIC, OR INTO FIRST GEAR WITH A MANUAL, AND CONTINUE ON.

Revised 11/20/2014

 

My front tires have equal thread, and I don't have a locker so I'll have to check the other things.

I have the 231 tcase. I've only used low a handful of times, but i use 4wd regularly. I would always just stop accelerating or stop and throw it into 2wd and it would disengage. Now I can do all the tricks of reversing, going into neutral putting it in 2wd and going back to drive, only thing that really seems to work is making a hard turn.

 

Have you tried what I offered in post 4?

 

I would pull the diff cover, sounds like your spider gears my be messed up. If they are not meshing correctly, and one or more have issues moving. If this is the case, it would allow the passenger wheel to freespin, while placing drag on the drivers side (or vice versa) pulling your vehicle to one side.

Did you ever look under the Jeep to ensure the driveshaft spins in 4x4? Do you have any noises that do not belong?

Also, check your alignment.