Yeah, I searched the forums, found many things helpful.

So, it can be the U-Joints? And what else?

Here is what happens:
Whenever I put it in R from P, clunk! then, it doesn't do that anymore and goes fine backward no matter how you are with the accelerator.
Then when moving to D, from R, I can hear the clunk again, a tiny winy bit lounder this time... and again, it goes fine.. and doesn't clunk no matter how hard you push. So, what it could be? U-joints? How do I check if they are U-joints? Can i put in D and let it run when lifted up on a hydraulic lift in a service station, of course for checking purposes. And just for confirmation, what is the idle speed of the 4.0 i6 motor?

 

block the wheels put it in park crawl under it and turn and wiggle the drive shaft

you should be able to see a bad u joint that way

 

and what else should I be checking?

 

Your symphoms sound like the u-joint is bad and needs replaced. The reason you hear it more going from P to R and though the remaining gears is there is no torque on the drive shaft. There is a constant torque on the joint when the vehicle is in Reverse and Drive. The torque is released when the vehicle is in Neutral and Park. When you shift the jeep the torque converter puts pressure on the joint and you hear the clunk, which is the bearings moving in the joint. While you have it up on a lift, this is a good time to check many items, shocks. springs, muffler joints, bolts holding the transmission spacer block, grease fittings, tie rods, sway bar links. This only take and extra 5 min. to check.

 

oops! I meant neutral

 

driveshaft u-joint should humm quite loudly on the highway.

but yeah, block the wheels, tranny in neutral with parking brake on and crawl under and grab the driveshaft in one hand, pinion in other and try to twist it for any play. you could also push it up and down to feel for any play that way too. should be none.

but for the 15 bux and a bit of time, change em out anyways.

 

Is your foot always on the brake when it clunks? Or maybe the better question is does it not clunk with your foot off the brake? If not, it could be worn caliper pins. Just something else to check...

 

umm, doesn't matter if my foot is on the brake or not, it clunks.. I'll check that tomorrow and let you guys know..

 

It sounds to me like your rear gears just have a normal amount of slack in them from miles and years of usage.

 

Haven't got time to check it.. and btw.. it hasn't even broken the 200,000 Kilometers barrier yet.. its around 190 right now.. :s

 

hey guys this is my first time posting. i just bought a 95 with an i6 and 250mi. its makeing the same sound so ill check it out tomorrow and let you know. thanks you guys are great!!

 

Plenty of kilometers for it to have developed wear. Who knows how the previous owner treated it? Maybe it ran low on fluid before.

 

I checked it, U-joints were fine.. but it had no OIL in the transfer case? I haven't got time to fill up the transfer case, but could that sound be coming from the TC? I can't identify that alone

 

No oil in the case? How long have you had this clunk?

 

You need to fill that T-case.

But your clunk could also be from a warn out tranny mount.