4wd is very loud, has a hard time going back to 2wd.

Ok so I have this '99 4runner that I bought used and 4wd was seldom used, if ever, over the life of the vehicle. It engages in 4hi but when it does, it's pretty noisy. I've never owned a 4wd vehicle before so didn't know if this is standard. I figured I'd hear a little extra noise but not as much as I'm hearing. it's a noisy gear sound. can't quite tell where it's coming from. Also the steering is pretty jittery when in 4hi...little bumps in the road bounce me all over the place. I tried going into 4low once and it kinda grinded a little...eventually went into 4low but then was almost impossible to get back to 2wd so never tried it again because I didn't want to mess anything up.

Also when I am in 4hi and try to go back to 2wd, sometimes it doesn't engage. Yesterday, for instance, I kept trying to get it to go back to 2wd, it wouldn't get out of 4hi...then I had to do a uturn in a cul de sac and in the middle of the turn it finally switched back over. Did turning have anything to do with it going back or was it probably just a coincidence?

 

I'd say check the T-case and front diff, as you get gear-y noise, but only in 4wd... rear should be fine since no noise in 2wd. 4lo should have an almost... whiny noise for lack of a better word.

 

Thanks for the suggestion. Yeah, I think I'll check 'em out to make sure there's actually oil in them and not just sludge...I'm suspecting the latter. hopefully a flush and refill will smooth it all out. I'll report back when I have a chance to work on this.