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4x4 doesn't work

MuddinJeeper

NAXJA Forum User
Location
Maple Ridge, BC
I can manually pull the shift lever back into 4hi/4lo, the part time light goes on, but will not actually engage. I suspect the vacuum linkage, but don't know what to look for. How would I determine if the linkage just got disconnected? How could I tell if its actually a Xcase problem? Thanks in advance!
 
Well....if the 4X4 light comes on then you have vacuum thru the Xfer case and on its way to the disconnect on the axle. I would check the vacuum lines at the axle (passenger side) and possable pull the shift motor to see it the shift fork is in good shape or has cracked.

This is assuming that you have verified that you do not have front wheel engagement.

Rev
 
Jack up passenger side axle, put trans in neutral, transfer case in 4-hi (or low),start engine, grab front drive shaft and turn by hand. Can't? Good, indicates transfer case working. Next, turn passenger side tire by hand. Turns? Not good, means axle not connected. Check all vacuum lines at the disconnect vacuum motor. One line should have vacuum. Part time light "on" indicates lines good to vacuum switch and to disconnect motor.
 
terrific! thanks so much! As you might tell I'm as green as they come concerning Jeeps...I appreciate the info.
XJToivo: IIRC I only hear clunking when shifting from drive to reverse.
 
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[FONT=Verdana, Arial] A really cheap option: remove the axle disconnect fork, manually slide the coupling collar over both shafts and hose-clamp in place. Now the axle is always engaged, just like it would've been if you installed a one-piece shaft in there.
[/FONT]

Anyone have any feedback on this mod?
 
If you really want to eliminate the disconnect feature, do it right by replacing the two peace axle with one. It's been discussed on this forum. Personally, I liked the ability to disconnect, insuring my front drive shaft didn't always turn. With 6" of lift, I got annoying vibration at speeds above 30MPH; however, I did have an occasional problem, always caused by either a broken vacuum line at the disconnect, or the whole harness pulling free. After extending the harness, never had problems again. But its location does make it vulnerable.
 
xjbubba said:
Jack up passenger side axle, put trans in neutral, transfer case in 4-hi (or low),start engine, grab front drive shaft and turn by hand. Can't? Good, indicates transfer case working. Next, turn passenger side tire by hand. Turns? Not good, means axle not connected. Check all vacuum lines at the disconnect vacuum motor. One line should have vacuum. Part time light "on" indicates lines good to vacuum switch and to disconnect motor.

I'm having this same problem '90 ,231, front disconnect

i did this after i wimped out and took it to a dealer. the dealer said it worked and i had no vacumm leaks at all and that all was well. took it home ,did exacually as you said xjbubba and the wheels spin when engaged!!! (drive shaft doesn't spin)what does this mean?!
 
the shift motor isn't working, you have no vacuum, or you broke the fork. check the vacuum connection on the motor. mine had slid off at one point, but still gave good vacuum...the only thing is that the vacuum wasn't getting to the disconnect motor...

XJ Bubba...my jeep is 4x4 only (weekend/emergency use only, primarily a trail rig), so I'm not too concerned about DS vibration. If I pull the motor, am I going to have to fill the diff again, or will there be any fluid leaking? I'm not sure what is sealed and what isn't on axles...
 
I have a 91 and had the exact same thing happening with mine. More often than not, the stupid aluminum shift forks in the housing break.

Take off the housing (4 bolts, 6 if you include the dust shield) but remember to catch the gear lube in a bucket. Unplug the connection to the light, unplug the vacuum lines, and pull the housing off.

Now look at the shift fork, if there is ANY play from side to side then I guarantee the fork is cracked. You might not be able to see it because it cracks at the hole along the rod. Take that POS aluminum fork outta there and get yourself one from a Dodge disconnect axle as they're cast iron.

I took one out from a '90 Dodge Ramcharger front axle (Dana 44) with disconnect, and it fit perfectly and I haven't had a problem since.

EDIT: Also, to make sure it isnt a vacuum issue, pull the housing off (but leave the vacuum lines connected) and hold the fork in one hand while having someone shift in and out of 4WD. I couldn't even hold the fork still, which meant that there was plenty of vacuum to move that loose collar over.
 
Sounds like a plugged line. Happens when you play in mud and the vacuum lines come off the disconnect. Easy to fix with a piece of wire, or replace the lines.

You can remove the vacuum motor on the axle, and it will drip a little, but not enough to worry about. The fluid level is about even with the axle tube when full. Since the seal is in the axle tube just to the right of the vacuum motor, some fluid accumulates in the disconnect housing.
 
Samman said:
I'm having this same problem '90 ,231, front disconnect

i did this after i wimped out and took it to a dealer. the dealer said it worked and i had no vacumm leaks at all and that all was well. took it home ,did exacually as you said xjbubba and the wheels spin when engaged!!! (drive shaft doesn't spin)what does this mean?!

You say "the wheels (plural) spin". Did you have both tire off the ground? With driver's side on the ground, the passenger side off the ground and the transfer case in 4-something (can't get the vacume to the disconnect unit without the engine running and the transfer case "in gear"), you should NOT be able to turn the passenger side tire. If the disconnect clutch is working correctly, your left and right axles are now connected, and the only thing that could turn would be the drive shaft. But, if the transfer case is in gear, the shaft won't turn. If you have both tires off the ground, and you turn one tire, the other tire should turn the opposite direction (unless you have a locker or limited slip diff) and the drive shaft won't turn. Make sure the driver's side tire is on the ground.
 
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