89 Cherokee XJ not shifting to 4x4 - vacuum issue

[gen2600]

Purchased the rig cheap from someone who had "the four wheel drive just quit" and never fixed it... Need this for my river/beach rig here in Homer, AK.

I've been doing research like mad (mainly on here), I've found some stuff but am really not connecting together in my brain (could be due to bad brains).

It really seems like a vacuum issue where the front axle is not engaging. On a quick glance to the passenger side axle, I see a disconnected vacuum hose:

(I cured the incredible oil leak that was happening too FYI)

...could that be the culprit? I found these diagrams talking about vacuum from the transfer case (feel free to link to them if you need):

...if I pop the hood and am standing at the grill, looking back to the truck, at the passenger side, there two vacuum lines coming out of the firewall, one is reddish and the other is black, both are disconnected... *sigh* - I hate vacuum issues. Input?

Yesterday was spent fixing oil leaks, cutting a replacement drivers side window out of a SuperCub window and repairing the door locks for both front doors. After the 4x4 issue is fixed, I just need to figure out the front end popping and steering debacle followed by shocks and it'll be a runner!

 

[cruiser54]

My suggestion is to pull the vacuum motor from the front axle, pull the c-clip on the shaft and slide the fork over so both axle halves are engaged. Reinstall the c-clip. Just eliminate that vacuum crap as the factory did in about 1991. You know when that vacuum stuff is gonna fail you, right? When you're needing 4WD.

Takes less than 1/2 hour start to finish.

 

[in4aride]

just convert to 1 piece shaft, done

 

[WrenchMonkey]

First off, bravo on the research, man!

Second, sorry, but I'd ignore it all and do what cruiser said.

Pop the cover, slide the collar over, lock it in place.

Done.

(Upgrading to a later one-piece shaft is great too, especially since you can gain the bigger 297 joint in the process, but it is more work and money.)

Robert

 

[lyleorszulak807]

Not to mention dealing with installing new seals which requires you to remove the carrier and figuring out which seals work....not worth it IMO unless somethings broken. Just move the fork over as previously stated.

 

[jap813]

This is confusing to me I have a 89 xj limited and DO NOT have the axle disco. Was it an option to not have this p.o.s. problem. My axle is completely stock and never has been changed out. But i would definetly get rid of the issue with the c-clip trick and be done with it.

 

[WrenchMonkey]

This is confusing to me I have a 89 xj limited and DO NOT have the axle disco. Was it an option to not have this p.o.s. problem. My axle is completely stock and never has been changed out. But i would definetly get rid of the issue with the c-clip trick and be done with it.

242 case?

The early XJ's with the full-time transfer case got the one-piece axle stock.

Robert

 

[jap813]

yes I have the 242 case

 

[WrenchMonkey]

yes I have the 242 case

There ya go, that's why.

Robert

 

[jap813]

so why not swap axles with one out of an xj with the 242 and not have the issues that go with the disco.

 

[WrenchMonkey]

Well, you can.

The really early one-pieces are pretty rare, but after 1990 they were all one-piece, regardless of t-case. So you could use any Dana 30 all the way up to 2001.
(Though the last couple years are low pinion, but that's another conversation.)

But you don't even have to swap the whole housing.

You can do like in4aride was suggesting, and install the one-piece axleshaft into the disco housing. You do have to redo the oil seals, because they're different one from the other, but that's a really common upgrade.

But the easiest, cheapest, fastest way is just to engage that disconnect collar, lock it in, and forget about it.


And we like easy, fast, and cheap.

Robert

 

[gen2600]

But the easiest, cheapest, fastest way is just to engage that disconnect collar, lock it in, and forget about it.

And we like easy, fast, and cheap.

These are a few of my favorite things...

Is there more info on the disconnect collar, locking it in etc?

 

[cruiser54]

Search CAD elimination. actually, it's so easy that you could remove the 4 bolts holding the axle shift motor on and take a gander and figure it out. The shift fork rides on a shaft and is retained by a c-clip. Remove the c-clip, slide the fork over toward the driver side on the shaft and replace the c-clip.

 

[GETSOME]

My suggestion is to pull the vacuum motor from the front axle, pull the c-clip on the shaft and slide the fork over so both axle halves are engaged. Reinstall the c-clip. Just eliminate that vacuum crap as the factory did in about 1991. You know when that vacuum stuff is gonna fail you, right? When you're needing 4WD.

Takes less than 1/2 hour start to finish.

Will this be a problem on the pavement?

 

[gen2600]

I think I found the writeup on this...

http://comancheclub.com/forums/viewtopic.php?f=9&t=18415

 

[cruiser54]

No problem at all on the pavement. As I said, the factory eliminated that crap in the later years. Check out the link that that gen2600 provided in the previous post.

 

[gen2600]

I went ahead and put the Jeep in the air, popped that cover off, just moved the shaft over (in the cover) and used zip ties to space the covers harness over to the side to keep the collar on the axle ends engaged... Seems to be working!

Edit: This really seems like something anyone with this vacuum setup should do...

Thanks all for the help .

 

[old_man]

Just a quick question. Does your cruise work? Does your heater only work on defrost? If so you problem was really a vacuum leak.

 

[gen2600]

Just a quick question. Does your cruise work? Does your heater only work on defrost? If so you problem was really a vacuum leak.

I will check that out later to be sure. However, all the vacuum lines coming off of the cover plate with the vacuum control switch were severed. Once I removed the vacuum control switch and plate and got to playing around with the collar inside, I saw how it was actuated back and forth by vacuum - not having those hoses attached to anything absolutely was the cause of my not being able to switch into 4x4.

 

[old_man]

Just for your info, those hoses are available pretty cheap from the dealer.