4x4 wont go in

[drock1970]

 :102:i have a 1988 wrangler and i was driving it today and i had to shift in in and out of 4x4 a few times and it did fine.  It will not go in to 4 hi or 4 lo. It drives fine in 2 wheel dr.  The 4x4 light on my dash is on all the time now. mechanically it seems fine (it will shift in and out but wont engage)  What is going on!!!!!!!!!!

[CRAZY LARRY]

sound like a vac. line is off or leaking

[drock1970]

Thanks, I'll do some investigating on that and let you know if that was it...

[YJ_Aaron]

Check vacuum at the front differential.  Most likely it or the 4 port plug on the top front of your transfercase is the culprit.

[militarytj]

where does the front diff. tube go? mine is just hanging up on the radiator, this jeep is in some bad shape.

[drock1970]

It's on the top, if your under the rig, look about where the floor panel for the gear shifts are, it will be just to the front of that directly on top.

[drock1970]

You should have 4 tubes coming out of that cap looking thing that I pointed out. As far as where the other end goes, spend $20 or so and get you a chiltons manual, just be sure it has the vacuum diagrams in it cuz some don't.

[militarytj]

ya I got a chilton's manual..... but I much rather hear and read from (( experienced )) jeep owners, makes for piece of mind Ha Ha

[YJ_Aaron]

Depends on which tube you are asking about on the front diff.  If you mean the one that comes off the third member it should run up your core support on the D.S. of the radiator and clip on.  That's just the vent tube.

If you are referring to your vacuum that engages your disconnect (on pass side just inboard of leaf spring) it should run to xcase.

[militarytj]

Ya, it's the vent tube...gotta be. Thanks brother. it's just hanging there tho. it's a new radiator in it.