So, typical problem xcept mine pops in and out. I took it out and inspected it(CAD) and all is good. I have replaced most of the upper hoses and the two that come from the CAD. It looks like there is some oil in the lines also.I have around 25 lbs. of vaccume just after the pump. Maybe the lines on top of the Tranny?

 

I bet its the plug that goes in the top of the transfer case.

 

So does this plug start leaking? I also found a green vacume line that runs up above the starter but it wasnt hooked up so I plugged it. 4WD works a little better but still pops out?

 

check the rubber connections on the vac line common spot is at the transfer case .oil gets on them and they get mushy and they don't seal tight any more any movement makes the transfer case kick out also the plastic tubing can crack

 

When you had the CAD out did you take a look at the ends of the intermediate shaft? When they aren't being held in tight they can slope the end of that shaft off and it won't hold no matter what. That's one reason I went to the Posi-lok, didn't want to have to worry about it anymore.

 

So I started off by splicing a tee into the vac.line and running a hose strait to the engage side of the CAD, started truck and yep 4WD is engaged. Next I found out online that the green vac. line is a vent, so I took my plug out and put the vent back in. So next I put new vac. line from the hard line to the rubber boot(plug) and nothing, so I put my vac pump on the steel line that goes to the engage side of the CAD that's on the frame, I started the truck and pushed over on the boot and got vac. I don't know when I can get a boot so I took it out and hooked the rubber vac. hose directly to the plastic nipples and the 4WD works great. Later Rocky

 

Well that didn't work. So I took and run a vac. hose strait to the engage side of the CAD and it still pops out so now i'll pull the CAD and inspect it and the shafts again.

 

Homemade Posi-Loc might be cheaper and longer lasting than fixing the CAD.
Instructions> http://www.jeepforum.com/forum/showthread.php?t=595515

 

Thats a cool idea; I check out that Jeep forum a lot. (I have a 91 cherokee).
Thanks for the post, my 4x4 quit working also, but now we're in the middle of the engine swap.

 

Until I can get parts rounded up, I took the broken (busted shaft) cad off my spare Ft.end and gutted it. I then cut a 5in. piece of allthread and put a nylok nut on one end with washer slide in
hole and add washers till the fork is tight then put nylok nut on other end making sure the fork is in what would be in the engage position throw some silicon in the holes and tighten nuts, engage coupler and bolt back up. Don't forget to plug both vac. lines and tape up the plug for the 4WD. Guaranteed 4WD.Since I only drive 3 blocks to work and maybe 60mi. round trip on the weekend to go snowmobiling It should be alright till a perminant fix.

 

The green vac line is supposed to vent to atmosphere to vent vacuum when things are being disengaged.

Joel