4wd randomly not working

[mujeeper]

I was wheeling today and my 4wd kept disengaging and engaging randomly. The T case is just fine. Everytime I'm in 4wd, I feel the 4wd gearing. The issue is up front. It's the connection to the axle. I had a buddy wiggle the connections with the jeep running and the 4wd would kick on. After a short drive, it would go off, then on again. All randomly. I've heard that could be the actuator on my dana 30 and that they are prone to go out. It's stock axle and about 150k on the jeep. It seemed like it would disengage when it got bumpy and/or uphill. Basically.....whenever I needed it. Thoughts? It's a 95 YJ

[showmejeephoarder]

axel kick out

had same issue years ago removed and cleaned found mud or ? in unit worked after cleaned sold jeep soon after bought tj. 4wd parts makes a kit to eliminate electrical with a cable pull is kind of pricey

[Guest]

The vacuum actuator and/or vacuum lines are the likely culprits. Check for cracks in the lines and replace if necessary.

[jagular7]

Ditto on TommyG suggestion. The YJs have a split long inner axle shaft. There is a collar that shifts to engage the shafts together. Its done with vacuum from the engine through plastic lines from a switch off the tcase. They tend to crack and break.

[mujeeper]

Is there an easy way to find a leak? Won't be easy trying to find a small leak on a hoes going from my t case to the axle. Should I just replace that? What about the actuator? replace that too? I just don't want to THINK i fixed it, then find out on the trail (again) that I didn't. If there's a suction in the hose, then can I do something like disconnect the front, plug the hole with my finger, shift in 4wd and see if I feel suction? Maybe try soapy water on it? If it's a VACUUM line, then there should be negative pressure and the soapy water check is out.

[Guest]

I would just replace the line. I can't completely recall, but I think the hose ends are integrated into the lines themselves, but I'm sure regular vacuum lines will do the trick as well with some work.

Yes, there should be suction but I cannot recall when and which line.

When mine went bad on my old rig I just took the vacuum motor apart, disassembled the engagement fork, stacked washers on the shaft to force it into the proper position and put it back together. You have to make sure to put the collar that connects the 2 shafts in the right position before you put it back together. The downside is that now your front driveshaft will spin all the time. Since it's not balanced you might get some vibes.

[mujeeper]

Well. I replaced the lines and no dice.... I suppose I could have someone feel the vacuum line when i shift in 4wd, but may be sometime till i get free labor here. Until then, Any ideas what else it could be. If I feel suction, I suppose it would have to be actuator? Is it easy to rebuild one of those or am i better of replacing it? Also, is the suction powerful enough to feel and is it constant or 1 quick suck? (.....I'll leave that one alone.....) If I DON'T feel suction, would it be the electrical harness it connects to? Looks electical at least. Not sure how connecting a vacuum line to an electrical harness produces suction.

[jagular7]

I had a 87 XJ for 9 yrs. It had the vacuum disconnect as well. My plastic lines cracked and I fixed them along the way with rubber vacuum rubber lines. Simple enough. Then wheeling in Wisconsin in the cold of winter, the fork broke. Its cast aluminum so I blamed the bitter cold temps. So I took a socket and locked the fork/collar on the inner axle. The socket kept pressure on the fork to hold the collar on the inner axle so it wouldn't come off by centripetal force. Still had a great time up there.

Pull the inspection cover off the axle. Don't worry, there shouldn't be anything by a fork that you place back on the collar. You can web-search for details. Bet someone has pics on it all.

[Guest]

What Mike said. When mine busted on the trail I stuck a socket on the shaft and called it good.

The wires are for the sender that turns the dash light on. Nothing important.

[spunebil]

Of all the lines are good, how is your engines vacumn ?
just a thought.........

[mujeeper]

hmmmm.....Sounds like I don't know as much about 4wd in the front axle as I thought. I thought the wires to the tubes were engaging the suction. If not, what is? Where can I check the engine's suction?

I read a little more. Sounds like there is constant suction from the engine to the TC. When 4wd is engaged in the TC, the suction goes to the front axle via vacuum line (although the 2 lines going to the actuator are only about 15" long and end at what looks to be an electrical fitting).

I guess I need to get her up in the air, off all 4's and start following lines. Anyone got any good schematics or diagrams of how the system works? I think once I understand how it works, I'll be able to pinpoint the problem.

[Guest]

Google at it's finest....

[mujeeper]

you are a god among men. Thanks! I'll let you guys know what I find out

[mujeeper]

Well, before I could work on it, I ended up replacing my suspension. I later took it to 4x4 land for new spring perches, mentioned my 4wd, & the rest is history. They took care of me & got my 4wd working. Apparently it was the switch on the TC. The fitting that plugs into the TC was busted so suction couln't always get to the axle. Seems to be working, but haven't really tested. Having seen what was pulled off and explained to me, I have little doubt I'll have any 4wd concerns (pending my actuator doesn't go out).

Of course, as Murphy & his stupid law will have their way....On my way home installing a new suspension, getting new perches on, 4wd fixed, pinion angle fixed, & ladder bar fixed, what happens? Exhaust broke. Thus why I haven't tested the 4wd much yet. Not bad for getting ~10 years out of my aftermarket exhaust set up.

Special thanks to Mike, Garrett, & the rest of the guys at 4x4 land for taking care of me! I'll be out there again sometime. It just depends on what I feel like breaking next....