knocking, tranny specifically

setup in question:
4.0L
AW4
NP242

After our first snow fall last week and some hi-way 4x4 driving (full time) my tranny now has a bad sounding knock. Its not constant, its not all the time. I can be in gear or not, in any 4x4 option or not. The only time it goes away is while in motion, even than if its slow I will get a rattle. So with it stopped I got under neigth and listened to where the sound was coming from. It not the engine, too far forward for the t-case, and it seems to be the houseing between the AW4 and the engine (that may be the front of the tranny I am not knowledgable about these things)
Now this will go on for a while, than after a drive (10km) its gone. Come back home its sounds fine, shift into 4x4 and drive, and it starts again. The sound is still coming from the same place but it seems to be activated (after going away) from shifting into 4x4.
The vehicle runs fine, shifts gears fine and I am bringing it in to get re-geared this week so it won't be on the road much and would be a good time to make changes/fix it if need be.

I have searched, read, re-read and searched some more but can not find anything other than;
bad motor/tranny mounts, exhuast loose, etc etc.

Seems there have been a few knocking threads lately, but none are this specific and none of what worked for them is working for me.

on a side note, with my 242 on a snowy wet slippery asphalt road what should I be driving in?
manual says slippery roads 'part-time' normal asphalt 'full-time' I am not sure of what I should be in for each road type, and don't want to bugar anything up... if I haven't already.

Thanks for any and all help

Possibly loose engine mounting bolts on the bellhousing (that housing between the tranny and engine), or a cracked flex plate. Do a search on cracked flex or drive plate and you should be able to find a bunch of writeups on how to pull the inspection cover and check for cracks.

well from reading threads found in the "flexplate" and/or "cracked plate" search its looking like the flexplate is bugared. example http://www.naxja.org/forum/showthread.php?t=101630&highlight=flexplate
so now I have to go about getting it fixed as I will be putting lots of road under the Jeep over the holidays.
Co-incidentally I am getting it re-geared at a tranny place, where a friend was gonna work on it after hours to lower to cost, with my help when possible.
I guess I should wait n see if in fact it is the flex plate. If it is, is this something the dealership would have in stock or should I call asap so I can get this done?
Thanks for the direction lawsoncl, much appreciated.
Now that I have this direction, what should I be looking for when I get there? broken what? cracked where? pieces laying around?

I think that I would locate a flexplate just in case,also the flexplate bolts may be loose,I have seen that before,better to have parts on hand:wave:

the bolts on the torque converter are known to rattle loose and they are easy to replace or tighten.

FatXJ said:

the bolts on the torque converter are known to rattle loose and they are easy to replace or tighten.

Click to expand...

I missed mentioning that, but yeah check those when you pull the inspection plate to have a look at the flexplate.

just to update for those who helped, and those who may have this problem in the future.

well I brought my Jeep in to get re-geared with the hopes they could have a look at that rattle.

I mentioned the flex plate and/or the torque converter bolts.

My buddy listened to the rattle for a bout 2 seconds and said it was to heavy a sound for the flex plate unless it had actually broken into pieces.
Called yesterday and it turns out it was the converter bolts, one had come out, others were loose. So they all came out, shot of lock-tite and re torqued and all is well again.

Thanks for the excellent help diagnosing this problem. Saved me mucho stress and money giving him exact location and symptoms on what it could be so he didn't have to go searching around for trouble.