SOLVED: 2007 JK knocking
 

I was hoping somebody could help me identify a knocking sound my 3.8 with 145000 miles is making. From what I've read it sounds like rod knock but I'd rather not drop the pan to check the rod bearings if I don't have to. There is a definite knocking sound at idle only when the engine is warmed up. The sound follows engine rpm somewhat. Just off idle it turns from a rhythmic tap to more of a random rattle like ball bearings in a can only deeper sounding if that makes sense. I can't get good audio of the sound or I'd post a recording. The sound goes away almost completely above 1000 rpm. Today I find a post where a guy found a misaligned rocker arm was causing his knocking and it sounded like rod knock. So I pulled the valve cover and the arms all look well aligned but when I wiggle them side to side I can hear a distinct tapping sound on 3 of them. It sounds similar to what I hear when it's running but that's so hard to judge. Could this be the sound I'm hearing and how the heck would I fix it? I'll try to get a video up but my phone records mp4 and those aren't allowed in attachments. Thanks in advance and apologies for the book.

Mine made that same noise right before it spun the main bearing...

Well that's encouraging, lol. I'm hoping it's rod bearings at worst. Guess I'll drop the pan. Any way to tell if it's the main bearings that are going?

Well I swapped the rod bearings yesterday. It's very strange, the noise can still be heard but it's a lot harder to make it happen. Makes no sense to me. The engine does seem to run smoother. I attached a pic of what the upper rod bearings looked like. I don't think they were too bad but definitely worn and starting to come apart. Now I suspect timing chain or oil pump as the culprit. Any thoughts on those things causing a knock/rattle just when revving barely above idle and when returning to idle? It's right around 800 rpms. I've also heard loose transmission mount could sound like this but it seems fine. I'm stumped and don't want to keep dumping money not knowing what it is.

https://cimg5.ibsrv.net/gimg/www.jk-...726fbc5f07.jpg

So it turns out the problem all along was loose torque converter bolts. Reinstalled the 4 if them with some red loctite and no more knocking at low rpm. Awesome. Hope this helps someone else in the future.