I suspect that this problem may be my torque converter valve. Whenever the jeeps in drive, and only in drive, and idling at a stop sign, a very loud rattling noise occurs. It goes away completely once I put any perssure on the accelerator and start moving again. Also, the sound is minimal or completely disappears once the jeep is sufficiently warm. From some reasearch this sounds like a torque convertor problem, and the reason I suspect it to be the valve is because it goes away when its warm (once the trans fluid is warm).
Any thoughts?

 

Could be the flex plate, just remove the inspection plate and make sure the bolts aren't loose, and the plate isn't cracked. Takes less than 10 minutes to look at it and tighten them, can't hurt even if that is not your problem.

 

I had a similar yet different problem before with rattling from down there - turns out last time my torque converter was loose. Ill take a look when I have access to a garage

 

Flex plate, Torque converter are good things to check.

most of the time it is the catalytic converter

 

My cat just started doing this last week

 

This may not be it but worth a shot...

i had some really loud rattling at idle and the same symptoms as you did and even the slightest accelaration it would stop too. so i popped on the ebrake and left it in drive and crawled under (totally unsafe but if you heard the rattling you would too) and there was a piece of metal between the body and the muffler, looks to be a heat shield??? well no more rattling and have checked to see if the surrounding area gets hot but doesnt, i think its because i gave an aftermarfet muffler.

worth a look

 

subscribing to this because I just had this same problem earlier today. I'll add my thoughts in the morning

 

I have no cat so thats not a problem. I recently got the flowmaster on, ill see if some of my rusty floor pan is rattling on that ^^

 

Try SLIGHTLY pulling up on your transfer case lever while in 2wd but don't disengage

I read somewhere in another thread that the linkage is ****ty and rattles and i didnt beleive that could be the problem

The next day i went driving and was so happy to find that was the problem!

 

I've never heard of a torque converter valve. Where is it located and what does it look like?

 

Check ALL of the exhaust hardware as well.

I had a nasty rattle at a certain RPM range, ( sorta like when you put it in drive it changes RPM a bit ), turns out an exhaust clamp was the issue.

Something is rusted, or just loose and resonates at a certain frequency causing it to rattle.

I found mine by laying under the jeep and kicking the exhaust with my foot.

Whatever is rattling may be expanding due to heat, especially if it is in the exhaust system and tightening up as a result. A slightly loose clamp may do this.

 

x2 also are there any heat sheilds that could be ratteling

 

the cat converter has a heat shield and its does get loose and rattle. carefull though cat converters get hot and start fires... so im told

 

Alright, I just crawled under my jeep to find a crack right smack dab in the middle of my muffler. Could this be part of my noise? (I am a total n00b when it comes to exhaust systems)

I couldn't hear the rattle when I crawled under the jeep so I just had to guess

 

I know this is an old thread, but worth a shot. My jeep is doing this and I can get the sound to go away if I push my brakes very hard while stopped in drive and it doesn't happen anymore. It is almost always when I hold normal stopping pressure on the brakes at a light, but stops if I mash them down. Not sure what the problem is, hoping to look into it more this weekend