i just got a 1990 jeep cherokee 4x4 pioneer and its the first 4x4 jeep i have owned but the 4x4 kicks in i can feel the low rang by how it shifts but the front wheels arent turning i have checked the fluid in the dif and the transfer case any suggestions on what it could be....... okay so the vacuum lines were broken and really messed up went to the auto parts store and they did not have it went to the junk yard and hooked up all three vacuum lines and now the vacuum is working but the 4 wheel drive still does not want to kick in right any other suggestions.

 

you probably have a vacuum disconnect front axle, it is acuated by 3 vacuum lines at the axle check the lines for leaks

 

ok will do thank you for your help

 

you can replace the vac disco motor, which is likely the culprit, but for the peace of mind, i'd just either get a posi-lok cable setup, or swap in a solid front axle or at the very least, a 1 piece shaft with the 297 joints.

 

so the vacume lines were a bad thing on these jeeps i have a 94 cherokee sport but its not 4 wheel drive im kinda new into the 4 wheel drive world

 

Good luck.

 

thanks for helping me out

 

yes, vacuum lines suck.
94 didn't use a vacuum disconnect front axle in their 4x4's. so no worries there, although yours is only 2wd, you have no transfer case either.

jeep stopped using the vac disco around 92.

 

No vac disco in '94? Cool. What does my '94 use to engage/disengage the wheels to the axle? Is it some sort of auto-lock hub??

 

your front axle/wheels are always engaged.
you get front drive when you pull the off road lever into either 4hi or 4lo.

 

Yep, this. That's why if you look under the Jeep while it's moving in 2wd, the front drive shaft is spinning. The older ones with the Vacuum disconnect didn't do this (I think it was vac-disconnect until '91, not '92).

 

Sooo, is it possible to save some gas money installing manual hubs? Has anyone tried this? If so, did you pick up some mileage?