90 cherokee no 4wd

[tvguy]

Help 90 cherokee no 4wd

Hey all been mia for a while but need some help with this 90 cherokee I picked up from the board(the one on jack stands white fort collins)so far every thing has been working out to get this thing on the road but the 4wd I am not familer with a 90 and I think it is vacum activated, no light(yes dummy light) when lever is shifted into 4wd or 4wd low need some help getting it working Have beer if anyone wants to meet up to help me out.
Henry

 

[xj_krawler400]

if its the stock front axle yes it is vacume activated, mine went out too, but i just dis connected the plug and blew in it / cleaned it pluged it back in and she worked just fine. i would try that plug ( make sure ur pl;uged in to start with haha )

 

[tvguy]

if its the stock front axle yes it is vacume activated, mine went out too, but i just dis connected the plug and blew in it / cleaned it pluged it back in and she worked just fine. i would try that plug ( make sure ur pl;uged in to start with haha )

It may not even be plugged in do you have a pic of what to look for??totaly lost on this one

 

[tvguy]

just checked it out all the vacum lines are pluged in but still no 4wd????

 

[YELLAHEEP]

Henry,

Basically, there's two components that affect the 4wd engaging.

The vacuum motor on the axle and the vacuum switch on the t-case.

Generally, the lines going from the vacuum sources are the first problem. You'll want to inspect them to ensure they're not cracked, or not sealing to the vacuum ports they're connected to.

Once you've determined you have the lines sealed, then you need to test the operation of the vacuum motor on the axle. Simply done - just get a length of hose, connect it to the disc shaped motor and suck some air in - you should feel resistance and plugging the end with your tongue should hold vacuum in the line/motor. If you can't create the vacuum, you have a bad motor.

If the motor is fine, then you'll need to remove the switch located on the t-case. It has 4 lines on a group plug going to it. The switch looks like a large hex nut. Turn it out and then do the same test connecting a hose to the ports. By pressing down on the ball bearing end that goes into the t-case, you'll be opening the valve to allow air/vacuum to pass through to the axle motor.

My money is on the axle motor being bad. If this is an XJ you plan on using a lot, invest in the posi-lock cable set up to manually engage the axle and get rid of that problematic vacuum system. Or, you can also remove the motor and 2-piece axle shaft on that side, install an oil seal in the D30 diff housing and run a solid axle shaft and do away with all the mechanical aspects completely.

There's plenty of write ups here and elsewhere on the net about the posi-lock and the solid axle shaft swap.

 

[tvguy]

Henry,

Basically, there's two components that affect the 4wd engaging.

The vacuum motor on the axle and the vacuum switch on the t-case.

Generally, the lines going from the vacuum sources are the first problem. You'll want to inspect them to ensure they're not cracked, or not sealing to the vacuum ports they're connected to.

Once you've determined you have the lines sealed, then you need to test the operation of the vacuum motor on the axle. Simply done - just get a length of hose, connect it to the disc shaped motor and suck some air in - you should feel resistance and plugging the end with your tongue should hold vacuum in the line/motor. If you can't create the vacuum, you have a bad motor.

If the motor is fine, then you'll need to remove the switch located on the t-case. It has 4 lines on a group plug going to it. The switch looks like a large hex nut. Turn it out and then do the same test connecting a hose to the ports. By pressing down on the ball bearing end that goes into the t-case, you'll be opening the valve to allow air/vacuum to pass through to the axle motor.

My money is on the axle motor being bad. If this is an XJ you plan on using a lot, invest in the posi-lock cable set up to manually engage the axle and get rid of that problematic vacuum system. Or, you can also remove the motor and 2-piece axle shaft on that side, install an oil seal in the D30 diff housing and run a solid axle shaft and do away with all the mechanical aspects completely.

There's plenty of write ups here and elsewhere on the net about the posi-lock and the solid axle shaft swap.

Sun of a B#@# I went and just got a new switch fro the transfer case and the fn line snapped in to the green one this sucks!!!!!! Also the red line that goes by the battery ans a black one? are just sitting there. Time to go back under this again and see what happens. Does napa sell the FN line kit or is it a bone yard thing??

 

[YELLAHEEP]

Sun of a B#@# I went and just got a new switch fro the transfer case and the fn line snapped in to the green one this sucks!!!!!! Also the red line that goes by the battery ans a black one? are just sitting there. Time to go back under this again and see what happens. Does napa sell the FN line kit or is it a bone yard thing??

AFAIK no one re-pro's those vac. lines. You can splice them with a section of rubber hose, but that's about it.

If you get into a pinch, I just picked up an '88 that might have the lines you need....... but it's got 205K miles and the 4x don't work either so it may have the same issues.......

Lemme know.

 

[Stang5lgt]

Sun of a B#@# I went and just got a new switch fro the transfer case and the fn line snapped in to the green one this sucks!!!!!! Also the red line that goes by the battery ans a black one? are just sitting there. Time to go back under this again and see what happens. Does napa sell the FN line kit or is it a bone yard thing??

Pass side back at the fire wall there is two metal tubes one with Yellow and one with Green lines run to it. If you pull the connector off and run a vacuum line from the engine to the yellow line tube you can get the motor to lock up the axle shaft if the motor is good. The green line should unlock the axle. Once you hook up the vacuum line to the yellow side start the jeep and 4wheel light should come on. Or you can jack up pass side and spin the wheel and see if the driveshaft spins. Mine is going tits up. I am going swap in a 93 axle since they didn't come with the crappy CAD axle.

 

[Fred]

The red line provides vacuum from the manifold to the system. Make sure you don't have a vacuum leak.

Fred

 

[tvguy]

thanks guys here is the situation...the red line by the battery is sitting there not hooked up to anything so if I am getting this straight this red line needs to be hooked up to the manifold correct?
I saw the tubes on the passanger side fire wall,yellow green, blue is hooked up to a round thing..
I am also going back to a bone yard I think I saw a posi lock on a jeep I was wondering what the red button was now I know.
I will post up tomorrow on what happens First round is on me thanks

 

[YELLAHEEP]

Henry, if you have a vacuum line running by the battery, I'm thinking that's the one that may go to the vacuum ball behind the bumper. Not certain, but IIRC, the older XJ's had two vac. lines going to the vac. ball and one of those is likely for the 4x4.

The manifold vacuum comes from a solid plastic line that runs from the manifold, back across the firewall and over to the cluster of vac. lines going down to the t-case. Again, IIRC.........



BTW...... I wondered if someone here picked up that white XJ.... The guy was gonna sell it to me a while back IF he couldn't sell it after that particular weekend...... you musta been the higher bidder. I'm glad - I didn't wanna do that drive out there! :thumbup:

 

[Stang5lgt]

I think the red one should be hooked up. There is one that has little disc on the end of it. It is check valve and should be just sitting there not hooked up to anything. I can't remember the color. But I was thinking it was red. It will have black disc on the end of it.
Here is diagram from a Dodge it is real close to the same.
http://www.dodgeram.org/tech/repair/4X4/cad_vac_sys.jpg
Only difference is the Jeep uses a line back to sensor for 4 wheel light. Not a indicator switch on the CAD.

 

[bd18packer]

Great discussion, guys (& gals, if any are here)! I have a 90 Jeep XJ, 315,000 miles and counting, bone stock except for the '95 inline-six High output engine(replaced the original enigne at 178,00 miles). This discussion has helped me diagnose an intermittent problem with my 4WD. Thanks a bunch. is the best 4WD organization in Colorado, bar none!

bd18packer
Somewhere in the Rocky Mountains

"Jeep, there's only one!"

 

[tvguy]

Glad you liked it I ended up just getting the posi loc going to install it after I get the shift fork(upgraded one) If anyone needs those stupid plastic lines let me know I yanked some out of a bone yard besides the ones I already have