1991 XJ 4wd wont engage
 

My 4WD is not locking my front tires up. When I put it in 4wd the front drive line starts moving but the tires don't lock up and I never get 4WD just rear wheel. I have heard it is vacuum lines, but where are the vacuum lines located? or is it something else?

First question is... do you have the vacuum disconnect front axle. This is identified by the shift motor housing on the passenger side of the axle housing.

What year jeep is it? Vacuum front rears were stopped around 1991 AFAIK. It could be an adjustment or the chain could be bad, how many miles on it?...Tj

Its a 91

Thank you for your feedback! I will check that immediately and repost. Thanks again!

250000ish miles

I do see the vacuum lines hooked to the passenger side axel. Are those needing to be replaced?

look for a disconnected vac line check the vac reserve tank under the front right bumper make sure no lines are disconnected

can you use you vent controls to switch from hi to low vents if not you may have a vac leak there

or it could be at the back of TC loose vac line or bad controller

With that many miles, I would put my money on the vacuum shift motor being faulty. They are not are a thoroughly sealed unit and water, dirt, and debris will get inside them over time. The rubber diaphram inside has a tendency to become dry rotted with age or damaged due to dirt causing it to lose vacuum pressure. Put the Jeep on jackstands at all four corners so the tires can spin freely. Remove the vac shift housing (4 bolts) and manually slide the locking collar into place. Then start the vehicle, place it in 4wd and see if the front tires will engage. If the front tires turn then start chasing vac lines to varify there are no damaged spots or leaks and do a vacuum pressure test on the shift motor. If not then the problem is within the differential or the transfer case.

I will check all those things as well.

The vent controls seem to be changing properly (defrost, vent, heat...) if thats what you ment.

Thank you EVERYONE for your time and input.