Chiefman

Rockin motion in park and OFF! Help! 98 Grand cherokee limited 5.9 V8 approx 100k and well taken care of. Drive 30-45 mins, pull into parking space, put in park, turn off and Jeep starts to rock back and forth with about 15-30 secs between forward/backward motion. What is it?

Bustedback

If it's rockin, don't bother knockin. It's probaly just the gas sloshing around in the tank that is causing the rocking.

Chiefman

I will try this again since I had one idiot attach some kind of ad to my post and some other fool quote the seventies "if it's a rockin...". I'm looking for a serious discussion here, not an opportunity for stupidity. the Jeep is run on the freeway for 30-45 minutes, pulled into a parking spot, put in park and turned off. It starts to push itself forward slightly then rolls back. This has been happening now on and off for well over a year. If this is a serious problem, I want it fixed. Now - are there any real contributors out there who can have a serious discussion or am I stuck with the current foolios? And NO it is NOT gas sloshing in the tank - really - what intelligence level of people do you usually read posts from?

Also the Jeep is a constant four wheel drive.

mithuth

I don't think you're going to get much help from anyone with an attitude like that. Humorously enough, I thought of the rockin' and knockin saying when I read your choice of titles. lol

The ONLY things that would cause movement is a mass of some sort moving around inside the vehicle. (obviously) So sloshing gas is a pretty solid suggestion. My TJ moves when I'm between 3/4 and 1/2 tank. The volume of gas is enough to move the vehicle slightly. Unless you have some sort of cargo strapped in the back or on the roof that is shifting after stopping, I'd still lean towards the gas rocking your Jeep.

Bustedback

Nice attitude buddy, good luck.

gclrick

check your blinker fluid

mithuth

Oh, and if you don't like our answers, perhaps you could ask the Jeep experts over at http://www.pirate4x4.com

Bustedback

Gasoline is about 6lbs a gallon, 12 gallons (about a half tank) at 6lbs each is 72lbs moving back and forth. Totally a plausible theory that it in fact the fuel sloshing could cause the rocking. But the original poster seems to know much more than any of us and is sure that fuel sloshing is not the problem, but yet he still asks for answers from us jokesters. And why worry about this rocking after all this time?

mithuth

I wasn't triyng to fight fire with fire and call him names or anything, but coming out and talking crap to people trying to help him is no way to make friends here or anywhere. After more than a year, if this problem was really a problem or issue, he'd have posted on other forums or taken it to a shop to be looked at.

I'm tellin ya, http://www.pirate4x4.com will fix ya right up.

Chiefman

If I don't have a sense of humor about this it's because I know I probably have a serious problem that I haven't been able to diagnose in a year and whatever the problem is, it's probably only getting worse and more expensive. I know this sounds unbelievable but it's not fluids of any sort. It's like something is not aligned and it's trying to right itself. Had front and rear differentials drained and relubed with a higher viscosity since drove on dusty CA canyon roads for 12 years. Mechanic thought differentials may have some binding go on. When the Jeep is turned off and you're still sitting in the drivers seat it feels like we're having an earthquake which is moving it a slight roll forward and back. Sometimes I hear a clicking or creaking in the back end center underneath.

And just so you don't get pissed off at Chiefman whom is disabled, I'm his wife trying to find an answer now for a year so I don't run the Jeep he loves into the ground. So for his sake, would you help out. I wasn't expecting to see some ad attached to my original first post and as a woman I'm tired of hearing answers about this that don't take the problem seriously. I am just as much a lover of vehicles as you guys are, I've changed out quite a few parts in vehicles before, and I grew up driving and fixing farm machinery with my Dad, so I'm not completely clueless. I know enough to rule out the obvious. This is different. I posted here because I thought you guys would get it, so if you can help, pls do. Thanks. I need the help- really.

mithuth

If you're driving it on pavement in 4wd, this is typically a huge no-no, try putting it in 2wd and see if it stops. i'm not 100% on the grand cherokee's full-time 4wd, but I can't imagine it doesn't cause problems driving it on dry pavement in 4wd of any sort.

The rocking/bucking/settling could be the 4wd system unloading after binding up on dry pavement.

Also, I recommend you drain and check the transfer case for metal shavings in the fluid or on the magnet.

Bustedback

If the vehicle is parked and the engine is not running, what else could be moving other than fuel sloshing in the tank! Do you set the parking brake when you park, or just rely on the parking pawl in the transmission to hold a 4000lb vehicle? Set the parking brake before placing the shifter into park and see if there is any change in what you feel.

Chiefman

Just to clarify, the 98 Grand Cherokee Limited 4x4 (only year it was made with the 5.9L V8) has quadra trac which is constant 4WD. It just can't be driven on cement in 4W Low, which it hasn't. Subaru is like this with it's All Wheel Drive, and several others. This Jeep doesn't have 2WD. You would have to do a major modification to convert it to 2WD and only if it was your last option before ditching the vehicle for another. When I was at my mechanic's we watched it being pulled into the parking lot several times because we noticed the left front drivers side wheel was struggling each time to keep up with the right side wheel as a relatively tight hard left turn was being made into the lot. Once we put the Jeep in Park, and engine turned totally off, no one in the vehicle, we noticed that the vehicle was rocking back and forth for 2-3 minutes with no power in the vehicle and no pre-ignition. That is when he did the work on both differentials to a Chrysler recommended viscosity, but it has not stopped the rocking problem. We also had the power steering pump replaced in the last month. Still rocking.
p.s. thank you for responding.

gclrick

wheels binding on tight turns= vc.

Chiefman

As for the parking brake - I got home yesterday, parked it on a 22 degree incline in front of the garage, put it in park, put the parking brake on, turned it off. Sat for a minute waiting and it started to move back and forth. Less movement than when it's on flat ground, but movement nonetheless.

We also had the transfer case drained and relubed with a better viscosity grease recommended by Chrysler (especially in this case because there were no other products available) when the differentials were done. No metal shavings were found in differentials or transfer case. Known mechanic for 20 years - one of the best in the area, and historically tells us everything if there is a problem. It's just this has stumped all of us.

Okay, I'm tired, what is vc?