Need some help with a 4x4 problem....

So I was on my way to work yesterday and was using the four-wheel drive, and on the freeway I suddenly heard a loud humming noise, almost droning. I put the truck in neutral, shifted it into 2H and disengaged the four-wheel drive. I got off the freeway and soon before I come to a stop, it felt like I had to hold the wheel to the right to stop it from pulling to the left, so I let go of the wheel, and it pulled really hard to the left. So I pulled into a gas station and looked underneath the truck but didn't notice anything unusual. No broken axels or cv joints. A friend from work told me it could be the u-joints because he has a similar problem with his F-150, but I wanted a few second opinions. BTW, it's a '94 Nissan Pathfinder w/ floor shift 4x4 and automatic locking hubs. Thanks in advance guys!

Wheel Bearings? I have sealed bearings on my tacoma, no way to grease themand If they go bad i find out the hard way.

possibly throwout bearing in the front diff. makes the 4wd not engage fully, so the axles "slip" in and out.

well, the 4x4 was fully engaged and I just took the front driveshaft out and found that the u-joints are just fine. When I had the issue, I wasn't thinking wheel bearing, because the noise was coming from kinda right under me (transfer case and front drive shaft). I'll check the transfer case fluid too while I'm at it, I suppose it could've leaked out. ughhhhh. :mad:

sounds like the hubs arnt disingaging, they could be all gumed up with shit

I would say hubs or wheel bearings, everything else would just make you go slow, not really pull to either side.

Where were you that you needed 4x4 on the freeway yesterday? Check your operators manual for exact numbers but these are some things I have found.

1. Don't use the 4x4 on the free way unless you have to, and if you do, you shouldnt be going over 55. I most cases thats the max rated speed for it. If you happen to hit a dry patch while changing lanes you will cause some serious binding in the transfer case and will most like like stretch the chain or break a tooth depending on the style of case.

2. If something feels wierd with the 4x4, stop and back up like 10 feet, this usualy helps lock/unlock what ever is sticking.