Who wants to diagnose a 4 wheel drive problem?

Ok everybody I'm new to the board so first off I'd like to say hi to everybody. I've been reading information from this site now for a long time but I finally registered not too long ago as I'm having some problems that I can't quite diagnose, and given the wealth of information between the bunch of you, I'm sure you can help me with some of it.

I own two XJs personally, an 86 and a 96, but this question involves my fiances grand cherokee. We just bought it a couple of weeks ago and it seems to have some problem with coming out of 4x4. When we bought it there were no problems with it going in and out and it worked good. But about a week ago I put it into 4 low just to show somebody who didn't know what 4 low was how it worked. When I put it back into 2 wheel I thought everything was good but it would still steer like it was in 4. Later that night a friend and I got under it and messed with the linkage and it was fine after that. Now tonight I put it in to 4 again and the same thing, it wont come out and it steers really jerky when going around corners. Anybody have any ideas on why even when it shows on the monitor on the dash that it's in 2 wheel drive it is definitely still in 4? When we were under it it looked like a lot of the bushings for the linkage were starting to get old, especially when shifting between 2, 4, 4 lo, would that have anything to do with it? It is on the transfer case definintely shifting though, could low fluid cause this? Any help is appreciated. Thanks a lot in advance.

id say get underneath, undo the linkage. put the lever in teh cab in 4lo and the lever on the tcase in 4lo, then hook back up and tighten. see if it works, if not post back up.

also, its possible it may be your vacuum disconnect for the front end. i am pretty sure the 86s had that (pretty damned sure). if its the 96, i doubt very much that there is a vacuum disconnect on the axle. so the linkage would be my guess

That's the other thing, on regular cherokees they run on vacuum. I looked everywhere on the axle (this is a 98 grand cherokee) and I don't see vacuum lines anywhere. I don't think these ones run on vacuum, the front driveshaft spins all the time, if that makes a difference, I think it connects and disconnects a the tcase itself and that's it...

Adam96 said:

That's the other thing, on regular cherokees they run on vacuum. I looked everywhere on the axle (this is a 98 grand cherokee) and I don't see vacuum lines anywhere. I don't think these ones run on vacuum, the front driveshaft spins all the time, if that makes a difference, I think it connects and disconnects a the tcase itself and that's it...

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XJs only had a vacuum-disconnect axle through the 1990 model year, I think. Your Grand shouldn't have one.

You probably need to adjust your shifter linkage. The procedure for an XJ is detailed in this post; if it's not the same for a Grand it should at least be a similar process.

This may sound wierd, but how are the tires? Are the fronts worn much more than the rear? All properly inflated? Try backing up, or shifting from 4 to 2 on a slippery surface.

Ok with more investigation I kind of figured some of it out today... A guy at my work told me to try to drive it in reverse, as you just said as well, and I tried it. It went right back to 2 wheel...he said that his 97 grand cherokee did the same thing and when he got it fixed they told him it was some kind of pins in the transfer case that are supposed to disengage, allowing it to go back into 2 wheel, that weren't doing the job and were staying stuck in the 4 wheel position. He said it has to do with how much gunk is built up in the tcase after so many miles. As far as I can tell this thing has never really had service. (original plugs, wires, etc. and it's a 98 with 133,xxx on it.) Probably a good idea to change the fluid in the tcase, anybody have any ideas if this will help to disengage those pins when they're supposed to? any good 'cleaners' for the tcase that will clean the crap out of it?

I'd do the whole thing, change the oil, coolant, thermostat, pressure cap, both differentials, transfer case fluid and you might want to consider having the auto tranny flushed on a machine. I'm guessing that you have a part time transfer case, thats the NP231, in that case go pick up 2 or 3 quarts of Mobil-1 ATF and use that. Note, before draining the transfer case remove the filler plug first, it's very annoying to drain it and then not be able to refill it becasue the you can't get the filler plug out

If you are going to keep it for a while I'd pick up a factory service manual, the jeep dealer can get them as well as the 800 number in the back of the owners manual, they can also be gotten on line but I don't remember the name of the place that sells them. The nice thing about jeeps is not having to jack them up to do this kind of stuff, except for the rear diff..