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NP231 pops out of 4 low

After messing with the linkages and doing every possible adjustment with them, I still can't get my transfer case to stay in low range. If I try to hold it in low with my hand on the lever, it will act normally for a few feet, then I can feel the handle start to kick back in sort of a pulsating motion until it just kicks itself out. Also, if I try to hold it in, the transfer case will make a lot of loud pops and bangs under power. Anyone have any idea what's going on here? The vehicle in question is a '95 XJ 4.0/AW4 with 3:55 gears, 33s and a SYE.
 
Did you try to disconnect the linkage altogether, and manually shift it to the desired position? It could be a number of things. Believe it or not, the last '99 my son and I fixed up and sold had a ton of change that had made it's way down through the console and had jammed the shifter.
 
Time to tear it down.

Elaborate? I know a small amount about how a transfer case works, but I'm far from a subject matter expert. What kind of parts am I looking to replace?

Did you try to disconnect the linkage altogether, and manually shift it to the desired position? It could be a number of things. Believe it or not, the last '99 my son and I fixed up and sold had a ton of change that had made it's way down through the console and had jammed the shifter.

I've owned this thing for the better part of 9 years, and there's nothing different about how the handle feels when I pull it back to the 4 low position. I keep it pretty clean, too- so no piles of change or liter-o-colas have been spilled down in there. I loosened up the adjustment and jammed the shift linkage on the side of the case back as far as it would go and tried it- same thing... only got a few feet and it was in neutral again.
 
To correctly adjust the the t/case linkage:

Remove the shift bezel. Pull the lever until the t/case is in 4lo. Place a 3mm (1/8") "shim" (drill bit) between the lever and the shiftgate, then secure the lever in place with a bungee cord.

Craw under XJ. On the top t/case shift rod is a square metal block with a bolt in it. That is the shift adjust trunnion. Loosen the locking bolt. Move down to the t/case where the lower t/case rod connects to the shifter tab. Use a pry bar or large pair of channel locks to fully shift the t/case into 4lo. Tighten down the trunnion locking bolt. Remove the bungee cord, the shim, and replace the bezel.

Other possible issues--engine and trans mounts shot, poor t/case drop kit installed.
 
If the trunnion is loose, the lever on the tcase is to the stop and it still jumps out, it has to be internal.

The shifter gate isn't supposed to hold the tcase lever in proper position.
 
if you disconnect the linkage, can you pop it in 4 lo with a crescent wrench? if so does it stay in 4 lo unlike what your currently experiencing? if it stays, then your problem is with the linkage and/or trans or motor mounts. if the problem persists, then it is most likely internal to the case.
 
My findings: It was partly linkage and partly the internals. Upon splitting the case I found that the chain was so worn and stretched that it was whipping up and hitting the shift fork. That coupled with the linkage being *just* off translates to all that popping and banging and no 4 low. With a new chain installed and linkage adjusted perfectly I'm ready to do some 'wheelin!
 
My findings: It was partly linkage and partly the internals. Upon splitting the case I found that the chain was so worn and stretched that it was whipping up and hitting the shift fork. That coupled with the linkage being *just* off translates to all that popping and banging and no 4 low. With a new chain installed and linkage adjusted perfectly I'm ready to do some 'wheelin!

Crap. I was hoping there was a simpler solution. I think I have the same problem and I really don't want to crack open my TC again. Ugh. Time for a rebuild kit if this is the problem.
 
Crap. I was hoping there was a simpler solution. I think I have the same problem and I really don't want to crack open my TC again. Ugh. Time for a rebuild kit if this is the problem.

Have you had to replace your chain a couple times before? Might be an incentive to get the heavier duty box from a salvage yard.

Info from a 5-90 post: (NP231C = Chevvy Version: K5, K10/1500, some K20/2500, and some S-series. NP231D = Dodge Version: Durango, Dakota, some W-150/BR1500, and some W-250/BR2500. NP231HD = Heavy Duty, NP231DHD = Dodge Heavy Duty. Typically, K20/2500, BR2500, and some one-ton Chevvy and Dodge.)
 
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