Hey guys my 89 MJ 4x4 not working.. Need some advice

[Brunner]

My MJ will shift into 4x4, but will remain in 2wd... I have vacuum sucking on the green hose to my actuator on my front axle.. Not sure if it's enough vacuum or perhaps something else is causing it.. Need some advice

[1987Comanche]

Will the transfer case shift into 4Hi and 4Lo?  If so the vac actuator in the CAD axle is bad.  The one on my '90 bench tested fine but wasn't strong enough to pull the lock collar over.  You can drill/pin the fork so the front axle is always engaged or put a cable actuator (Posi-lock I believe) on it.

[Brunner]

Yes it will shift into 4hi and 4lo

[metrictonner]

If your PART-TIME dash light doesn't come on the front axle dog fork isn't shifting.  Either that front axle slider box is not getting differential oil to lube the dog gear so it can slide or the front axle vacuum motor needs to be replaced.  Take the cover off and see what's up.  The whole thing isn't hard or expensive to overhaul.  Just buy a vacuum motor kit and make sure you put the dog fork tangs in the dog gear grooves when you bolt the thing back together.

[Brunner]

I have the cover off, the fork will not slide over to 4 wheel drive... I can put my lips on the actuator and move it that way. All it will do is keep it in 4wd

[cruiser54]

Just do this and be done with it.

 

http://comancheclub.com/topic/17377-cad-fix-1/