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post #1 of (permalink) Old 12-19-2005, 10:35 PM Thread Starter
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First Snow and no 4x4 Need help with Vac. Disco.

Ok we havent had snow or ice in december as long as I can remember (portland or) and we got some yesterday, bad time to find out the front D30 vacuum axle isnt engaging! So I know they are fairly untrustable, but all the extra cash went to christmas for the kids, so is there anything to do other than a posi lok? It has vacuum coming in, one hose has vacuum in 2wd the other has it in 4wd. Is it possible its just gummed up or is the unit fubar? Anything to check? It also has wires going in, are these just for dummy lights or the computer? Any suggestions are greatly appreciated, I plan to put a posi lok in after the new year but dont want to be 2wd til then, thanks

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post #2 of (permalink) Old 12-20-2005, 01:11 AM
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Re: First Snow and no 4x4 Need help with Vac. Disc

Is there a diaphram in there that just has a tear? Possibly try swapping one off a doner YJ until you do the posi-lok.. Or you can do some of the work yourself, and go with the $20 version @

Good luck..

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post #3 of (permalink) Old 12-20-2005, 08:00 AM
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Re: First Snow and no 4x4 Need help with Vac. Disc

You seem to have a pretty good idea of what you are looking for under there...but this diagram from Beee420 might help (or not).

If you do have all the vacume working correctly you then have to determine if it's the actuator on the axle or the solonoid on the t-case. You are gonna need a mighty vac or similar vacume gauge. Use it to apply vac to the shifter (on the axle) and see if the fork is moving. If it seems to be working at the axle...then your problem is with the "sender" on the t-case.
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post #4 of (permalink) Old 12-20-2005, 09:00 AM
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Re: First Snow and no 4x4 Need help with Vac. Disc

The wires on the axle actuator are just for the 4 wheel drive light. So when the actuator slides fully, the light comes on. No light, no actuator sliding over. If light is on, actuator has slid over. Conversely, if the light doesn't go out, the actuator has not slid back to 2WD.

They can get gummed up. Take the actuator off, see if it slides freely back and forth by hand. Pull a vacuum off the motor and try to actuate it in your hand. If it's tight, put some oil on the shaft inside the actuator - there are bushings in there that the shaft slides in, that can get dry.

If it's deadso (torn diaphram), you can just slide it over and put the front end in 4WD, and just drive it with the front end locked in, and change the transfer case from 2WD to 4WD. TJs are like that all the time - they don't have a disconnect. You might lose 1-2 mpg in 2WD spinning the whole front end, but it's not a big deal. I run my front end locked in all the time. I've also taken the disconnect apart, and shimmed it over so it can't slide back to 2WD on it's own, too. Then I took out all the vacuum lines and called it done. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Good luck
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