'89 front disconect??? help

[Infidel Edition]

So my 'part time' light is perm on.
I was thinking it had t be a vacuum leak... and crawled under
The connections look good, but the little hockey puck shaped piece is loose.
Here's a couple pieces...
As you can see, it rotates. And does so freely.

Do I need to clean that off to see if there is damage? Or is it most likely shot?
Thoughts?

Thanks

[4.3LXJ]

There is a little snap ring on the inside that holds it in, so it can rotate. That is normal. How many vacuum lines going to it. Can't tell from the pic

[Infidel Edition]

There is a little snap ring on the inside that holds it in, so it can rotate. That is normal. How many vacuum lines going to it. Can't tell from the pic

There's 3 lines connected to it. Not sure if all 3 are vacuum though... 1 may be a sensor wire telling the dash to light.
How many should be there?

My initial guess was 1 vacuum line and a 2 wire connection. But I'm not that familiar with vacuum based equipment

** I am going to hit the car hand spray car wash and try to clean up the u dear side more...

[4.3LXJ]

White and yellow engage and disengage it. Green goes to the 4Wd switch for the dash light

[Infidel Edition]

White and yellow engage and disengage it. Green goes to the 4Wd switch for the dash light

Cool.
I'll clean it up and track them all to make sure they are good.
... so the green to dash light. It connects under the hood I assume?
I ask because I've notices a "hiss" sound under the dash immediately after I turn it off. Lasts 5 to 10 seconds.

Thanks

[4.3LXJ]

It connects to a vacuum/electric switch next to the blower motor.

[Infidel Edition]

It connects to a vacuum/electric switch next to the blower motor.

I followed it best I could. But didn't find the issue.
Can I use my break bleed vacuum to do a vacuum test on it? And what would I check the voltage against?

... while following the lines ~ I found my water temp plug unplugged. Then in driving I noticed the temps never went that high.
Given the previous owner, I decided to check the thermostat and discovered that there was no thermostat!

Also found a blue vacuum line under the water overflow
I couldn't find anything near it to plug it to. So I capped it.
What the fffffff is up with all the vacuum line and parts. They're everywhere!

[4.3LXJ]

Yes, you can test it with any vacuum pump. If it leaks, replace it. The voltage is 12V in and when switched is 12V out

[Infidel Edition]

Yes, you can test it with any vacuum pump. If it leaks, replace it. The voltage is 12V in and when switched is 12V out

Where do I measure at?
The collection of 4x4 disco lines go somewhere behind the engine...

[4.3LXJ]

They go to the vacuum switch on the tcase

[Infidel Edition]

They go to the vacuum switch on the tcase

Is there an electrical point there to measure?

[4.3LXJ]

No, just vacuum

[Infidel Edition]

Yes, you can test it with any vacuum pump. If it leaks, replace it. The voltage is 12V in and when switched is 12V out

OK. I was thinking there was a test like for the MAP sensor where 5 Lbs gave X voltage vs. 2 Lbs gave Y voltage.

So, what's the pressure I would be testing for?
...and what's the best point to measure at?... at the disco? or by the tranny?

[4.3LXJ]

You need to check the disco at the disco. You can check the switch with vacuum too. It only has one line in and the 4WD light should go on if the bulb is good

[Infidel Edition]

OK my vacuum knowledge is less than steller. But the reason the light is lit is because the axle is engaged.
I checked it while the front end was on stands. Turn I g the passenger wheel turns the driver side and the front drive shaft.
Which is why it felt odd when turning I think.

So if I hook the pump to the disconnect line (vs the engage line), that should disengage it... right? I mean my hand pump I use to bless the brakes.
Right?

So is there a good right up on rebuilding that system?
I drive a lot of highway miles and don't want the axle locked 24-7. I'm even thinking of getting the cable disconnect option

Anyone?

[4.3LXJ]

There are several things to check. One is the vacuum switch on the tcase. Make sure it works right. It might not. Happens now and then. Make sure with your vacuum bleeder that the diaphragm is good in the vacuum motor on the axle and make sure all lines are OK

[Infidel Edition]

Looks like 2 of the 4 vacuum lines off the TrCase don't hold air.
Least not on the pump.
They're good up to the coffee can canister under the radiator fluid overflow.
The pump at the axle (when I pulled it switches back and forth / once I cleaned the dirt out of 1 plug)
But I hear 2 lines leaking when I run the pump....
I think its a connector. But maybe the entire line.

Next free weekend.

[XJ Wheeler]

The lines are cheap and pretty easy to replace.

[Infidel Edition]

The lines are cheap and pretty easy to replace.

The plan is to pull the disco off...
Plug lines in (won't be the default color coded necessarily) and fire up the engine.
Shift into 4x4 and check the position of the fork.
Shift out of 4x4... and check...

If all functions as it should.
Cut the engine and reinstall the disco.

Still on stands start it up. Still in 2x, turn the passenger side wheel and watch driver side wheel and front shaft.
Shift into 4x4 and repeat...
Then back to 2 and repeat.

If all is good to go, :D
If not... then I'll change out the actuator and try again:poke:

Fingers crossed

[ParadiseXJ]

Do I need to clean that off to see if there is damage? Or is it most likely shot?
Thoughts?

Thanks

Yes, cleaner is better. Then you can see things...and things work better.


My initial guess was 1 vacuum line and a 2 wire connection. But I'm not that familiar with vacuum based equipment

** I am going to hit the car hand spray car wash and try to clean up the u dear side more...


Is there an electrical point there to measure?

The P/T light switch is mounted on the passenger fenderwell just forward of the blower motor. What your picture shows is just a check valve. The switch is usually blue, its got a vacuum line to it, a ground wire and a power wire. When the t-case is engaged there is no vacuum to the switch, so the light comes on...if you have a leak or that vac line is not attached to the switch, the light comes on. If the ground is missing for the switch, the light comes on.

Get familiar with your vacuum system. So many little things run off vacuum and so many people theink they can just rip out vac lines or patch them with duct tape that it's the cause of many gremlins.

As far as the CAD axle goes, if you wan't to eliminate counting on vacuum to run it, do this very simple mod.

http://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/

Be sure to plug all the holes so you don't have leaks. After doing this you'll only have to worry about t-case activated by linkage.

[Infidel Edition]

As far as the CAD axle goes, if you wan't to eliminate counting on vacuum to run it, do this very simple mod.

http://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/

Be sure to plug all the holes so you don't have leaks. After doing this you'll only have to worry about t-case activated by linkage.

I thought about that... and effectively, had been driving around that way because the failure left the CAD in the locked position.
But I figured if it was an easy fix... I'd fix it rather than "over ride" the system.

[ParadiseXJ]

I thought about that... and effectively, had been driving around that way because the failure left the CAD in the locked position.
But I figured if it was an easy fix... I'd fix it rather than "over ride" the system.

Driving around the streets with your t-case in 4x will kill your t-case.

Fixing the stock system IS an easy fix. Just make sure ALL your vac lines are in good shape and that your vac servos and valve all work and that you understand how it works. Piecing it together makes it a hard fix and an unreliable system.

Locking over the axle is easier and more reliable and will not affect the way your Jeep steers or rolls on the road.

[Infidel Edition]

Driving around the streets with your t-case in 4x will kill your t-case.

...

Locking over the axle is easier and more reliable and will not affect the way your Jeep steers or rolls on the road.

The t-case was in 2x.
Just the front axle was locked. And on really tight turns, I'd get that wheel chirp from time to time on cement (ie. the parking garage at work) that just annoys me.