4wheeldrive not working!:(

I took out the jeep to play around with the other day. I engaged and locked the 4wheel low and it worked for a bit. After about an hour I tried claiming a little hill but noticed that both of the rear wheels were turning but not the front... What could this be?

 

did it pop out of 4wd? are the hubs locked in? front drive shaft broke?

 

Unless you heard a loud bang, probably not an axle. Assuming the TC was engaged properly, I'd check spider gears (notorious for breakage), or a hub that won't engage (only takes one).

 

Checked to make sure that it did pop out of gear and good. Checked the hubs and they were locked when in 4wheel. Drive shaft looks like its good.

How could I check to see if the hub is engaging? Could it be that they need to be lubed?

 

Put it in 2wd. Lock the front hubs in. Try to turn the front driveshaft by hand. If you can turn it, something in the front end is broke - spider gears, hub, etc. If you can't turn it, or you feel the Jeep try to move when you try to turn the driveshaft, something in the tcase is broke.

 

Thanks! It looks like something in the front is broke... I put it in 2wd, locked the hubs, turned the driveshaft by hand and it turned. What do would you suggest I start looking at? Should I replace the hubs first?

 

Pull the diff cover. You probably have busted spiders.

 

I'd start with the hubs. If it's not them and you have to do spider gears you will have to pull the hubs anyway. You'll be ahead of the game. When spiders go it's usually with a bang. If you didn't hear anything it's probably a hub. Maybe you have one that's not engaging. Here's another test for ya. Put the t-case in 4wd, lock the hubs, jack up one wheel (front) at a time. Try to turn the wheel you have up. If the hub is good and the axle and spiders are good it will try to turn the driveshaft but the t-case won't let it. If you can turn the wheel something is broken on that side. Hub, axle, side gear or spider.

 

This won't work if he has an open differential...

 

Yes it will. Common method of trail diagnosis. As long as it's in 4wd and one wheel is still on the ground.

 

I guess that depends what year the Jeep is, or more importantly what front axle he has. On an open knuckle like a Dana 30 the test still works but Mr. Nightstr will have to watch the u-joint in the knuckle to see if it’s spinning. If it is then set that tire back on the ground and lift the other one doing the same thing. If both u-joints are spinning then the issue is in the differential.
But that test doesn’t work on a closed knuckle front axle.

 

If close knukkle juste put un 2wd with the lock in, try to turn the drive shaft to make sure it's not engage in the t-case and just move the jeep a few feet and have a buddy looking at the drive shaft, if it's turning problem is in the t-case if not it's in the axle the problem.

 

I don’t get how, maybe you can help me understand better. It seems to me that if the lockout hub on the side that is still on the ground is bad the lifted tire will still spin because the open differential is releasing any tension between the spinning axle and the drive shaft by spinning the shaft that isn’t mechanically connected to a lockout hub.

 

You're right Corveeper. I hadn't taken into account the likelyhood of the other side being broken. Ooops! In either case, I'd still start with the hubs. If one of them is the problem he won't have to drain and refill the diff for no reason unless he just wants to look in it. Since he said there was no "bang" I'd want to check the linkage too. Maybe the body shifted and it's not going all the way into 4wd. Never heard a hub, axle or spiders break silently.

 

Ok good, I thought I was going crazy for a minute, jury’s still out on that one though.
Agreed that I’d still start at the hubs, if the spiders/sides are bad the hubs have to come off anyway.

 

I could be out of line, but I always thought that, with an open differential, if you jack up one wheel and spin it - with the other on the ground - the differential will slip the torque/power to the other wheel. All that would tell you is whether or not the spider and side gears are still intact. That would answer one of his questions, about the spider/side gears, but nothing about the hubs or the transfer case.

But, again, I differ to the knowledge of the group... I could certainly be wrong.