Hi guys. So when I first start the jeep I hear a thud thud noise under the driver side seat. Once started it's fine. Then when I give it gas it makes the noise again (thud, thud thud) and then goes away. After searching most people say there are probably transmission to engine bolts missing or it's the engine mounts. Upon inspection I found these two bolts missing.

My question is, could the sound be coming from here (visible fluid in the area) and if so, does anyone know the size of the bolts that should be here? This is looking at the trasmission from under the passenger seat area. I also removed the front driveshaft and it wasn't that. Cherokee is a 2001 automatic 4x4. Thanks guys!

 

From your picture I'm pretty sure those are the bolts holding the bellhousing onto the rest of the trans. The bolt on from the inside, no the outside so you might just not be able to see the end of the bolt. They usually aren't long enough to actually poke out of the hole.

A good possibility is that your driveplate/flexplate bolts are a little loose. There are 4 bolts that hold the plate to the torque converter that can sometimes vibrate loose. It's remedied by pulling off the inspection cover, removing each bolt, putting some blue loctite on it and reinstalling/torquing.

Here's a writeup:
https://www.cherokeeforum.com/f51/ho...ocking-125547/

Not sure if that's your problem, but it can't hurt to check. Just pull the inspection cover off the bottom of the trans and see if the bolts are tight.

Another possibility is your exhaust someone coming loose and hitting the trans or frame? Grab it and see if you can make it hit anything.

 

Thank you for the reply and suggestions. I did check my exhaust but apparently not thorough enough. Looks like my front exhuaust pipe hanger broke and the exhaust is laying on the transfer case member causing the noise. Now I just need to remove 16 year old exhaust bolts that don't look like bolts anymore ha thanks again!

 

First place to look for what you describe: