Zj heep

It could be fluid draining back from the converter in the trans. Try changing the trans fluid and filter and have them check the pump pressure.

721

Are you guys fat? If I give my Jeep a real good push while it's in park I can feel it rock back and forth. I assume if you guys where fat enough, just moving around inside the Jeep would cause this rocking motion

Chiefman

No we are not "fat". In a prior post I said the Jeep was rocking with no one in it. You can get out of the Jeep (in park, parking break on, vehicle turned off), stand next to it, and watch all four tires roll the Jeep slightly forward and back, over and over. At the mechanics, five of us stood there watching it move with no one in the Jeep (to our disbelief)!

As far as the transmission, we had the fluid flushed and changed and had to put a new pan on because of a manufacturer recall. This has been done within the last year.

Bustedback

You have the NP249 transfercase in your Jeep, it is possible that the viscous coupler may be at fault. Any noise while making sharp turns?

721

Swap in a NP242 to replace the NP249 for better gas mileage and fewer VC headaches, it'll be about as much as a new VC anyway.

The only thing I can think of outside of fluids would be the plates in the coupler still spinning after shutdown, causing the drive shafts to turn ever so slightly, making the Jeep rock. It doesn't sound very plausible, I'm not sure if the plates/VC would have enough rotational mass to move a 4,000lb vehicle, but never say never I suppose.

Chiefman

Now that, gentlemen, is a possibility. Thank you so much for looking at this differently, and your time looking into it. I found online where a guy had that problem and found a way to get in there without tearing everything apart. I'm trying to find the info again for my husband. I'll be handing this over to Chiefman to start responding as he can (he is in constant 24/7 pain) so please hang in for future posting from him. Again, THANKS (and now I know what VC is!)

gs69350

My 98 limited is doing the same thing. I'm positive it is the VC. My theory is that it lets the 4wd get in a bind and it tries to unload itself while parked. If I go to park and notice it rocking ill sometimes back up a few feet and turn the wheel a few times to unload the tension and then park, it usually doesn't rock after that.

Chiefman

Okay, this is me (Chiefman)and I apologize I haven't been able to get back to you guys but as my wife said I'm in pain constantly and I've really been going thru a rough time. There is alot of info that you all have given me and it's going to take me a couple of days to look into what you guys are saying and the extra info my wife has pulled up on it. I had done some research myself. I tend to agree with some of you gentlemen that say it's a VC. I haven't been able to figure out about how difficult or expensive a job it is to have done. I just replaced the power steering unit. I had the Jeep checked for 4Wheel Alignment, and was told alignment was good, but I was told by the same mechanic that I needed to have the steering box replaced. Is there any kind of a test I can do myself to prove this to be true or not? Thanks again for all of your input and as soon as I can I will bring you up to date. My wife tells me that she also tried putting the Jeep into Reverse (after I suggested trying it) and reparking but in her case she still got some residual rocking. I have had the same success you did by using reverse but because I'm disabled she is the one driving 99% of the time so deals with this problem more than I am. And again, guys, I really appreciate your time on this. I can't say thank you enough.

721

A viscous coupler will probably run you $400 new, labor, not cheap, most mechanics would want to/have to drop the transfer case to change it out.

FYI, you can't do a 4wheel alignment on our Jeeps, as the only thing that can be set in the rear is caster, which only changes with a lift.

As for a steering box, not sure, if it drives fine I would leave it alone.

jnicewan

Chiefman, you kind mixed in some issues with power steering into the other complaint. does it seem like you have a problem with the power steering? Does the vehicle shudder/chatter when cornering or turning in parking lots? That too would be and indication that the VC is failing.

When the VC starts to fail they usually grab tighter or make it seem more like a part time 4wd in 4hi. When the driveline is bound up a bit and then parking it the tension then tries to unload by itself, that is probably what is making the truck rock back and forth. The theory is hard to grasp but that is really the only thing possible and its also a part that is notorius for failure. The only thing that may make this seem worse is the possibilty of worn trans or motor mounts or excessive driveline play.

jronald

If it is the VC, then driving it straight for say 100 yards before parking it, will/should stop most of the rocking. Its the turning that throws the VC into fits.

Ron

Chiefman

Gentlemen, again thanks. You were correct about the 4 wheel alignment, no such thing on this vehicle. Please understand, because of my disability, I haven't been near any vehicle mechanically since 03. I truly do appreciate your input, but I hate wasting your time(as now).
Tire wear is great, all fluids are where they need to be. Not to waste any more time, I'v checked everything that each of you suggested, and all were as specifications stated.
I realize that it was a lousy process, but I have deducted as some of you early on did that it must be the V.C. (imagine that).
Earlier this year Billie #789 stated this in a different thread and went on to say that the V. C. can be replaced with the transfer case in the jeep (1998 Grand Cherokee 4x4 w/ 5.9 engine, and constant 4wheel drive) by removing the Tailshaft case, a couple of snap rings and you're home free. This makes it sound like it can be a relatively easy SOP to do. Can Billie 789, or any one else explain with any detail, or direct me to where I may find such info. On a scale of 1 to 10, which is the most difficult and more expensive? Replacing the V. C. with the T.C. in the Jeep, or out? Or to complicate things further, should I replace the entire Full Wheel Drive Trans case to an All Wheel Drive T.C.?
Wow, what a mouth full! I do hope I've made myself understood.
In advance, thank-you all for all of you understanding and much needed help
Chiefman!!!

721

Replacing the VC with the case in is going to be a 8 out of 10 job, dropping it will be a 6 out of 10, it's just much easier with it out. And you would want to go the other way with the transfercase swap, you currently have the AWD setup with the VC, you want to go to the 2WD --> 4WD drive setup of the 242 or 231 transfercase's (which don't have a VC). That'll cost just about as much as a new VC and I would say it's a 7 out of 10 job, depending on experience.

country_boy454

Try removing the front driveshaft and drive it for a while. That will take the load off the front and should eliminate the binding or unbinding your getting after parking. If it does then that is a good indicator that the VC is/has gone bad.

Typically many people who own the NP249 Tcase, found on many Grands including your 5.9, replace it with either the NP242 or a NP231 after the VC goes bad. You can usually pick up rebuilt ones for what it will cost you to replace the VC in your NP249.

I am going on 1.5 years since I removed my front driveshaft on my 249. I took mine off because I turned the front CV on the driveshaft into a bunch of shrapnel off road. Have a replacement for it but havent gotten around to putting it on!

94zjdriver

Chiefman the way I understand it to check the sterring box, get the front wheels off the ground, have someone in the vehicle turn the sterring wheel back and forth, be under the vehicle and look for the pitman arm moving before the wheels or linkage start to move. If there is movement in the pitman are the sterring box is bad and should be replaced.. Usually by this time you notice a wandering in the lane of your vehicle, If it needs replaced the 99 or 98 Durange 4x4 box without snowplow option is a good replacement... It will give you fewer turns lock to lock and is a much beefer box, especially it you are going to do a lift or tires or both.. Hope this helps.. There are several threads on replacing the box on other jeeps it appears to be a bolt in and an afternoons work..