My 3.8 2010 (auto, rubicon, 2 door) is making this sound:
It's not my video but it sounds exactly like that when it's under load, either accelerating from a stop or going up hill. Unfortunately the person who recorded the video never posted an update. I already replaced idler pulley, tensioner, drive belts, serpentine belt.

 

Sounds like detonation. Bad fuel, carbon in the combustion chambers, bad ignition timing, overheating, are possible causes.
A bad knock sensor may lead to detonation. It's there to prevent knock by adjusting timing and air/fuel ratio. Even a good one has a limit to what it can do, though.
If what you are hearing is detonation, you need to get it looked into soon, before permanent damage to your engine occurs.

 

thanks. It isn’t as loud of frequent as the video, much more subtle.

 

I based my response on the fact you said "it sounds exactly like that", referring to the video.

Now you are saying "It isn’t as loud of frequent as the video, much more subtle."

Not much we can do until we hear what your JK actually sounds like.

 

Is this a Manual or Automatic. If this is a Manual, whats the engine sound like in neutral. And when you increase RPM"s? And when you start in the morning with a cold engine. To me you're describing clutch chatter. If this is a manual, how is shifting gears. And going into reverse. Does it slip out of gear.

 

Thanks for the reply - I drive a 2010 Wrangler Rubicon (2dr, automatic). The noise for me is more subtle, you can hear it under the engine noise, happens the most when the engine is under load (accelerating or going up hills).

 

It would most likely be a good idea to find a shop that is familiar with 4x4 Jeeps (it helps). Take it in, leave it over night to check out that engine/transmission and have them do a complete vehicle inspection. It will cost you but you will be surprised what they come up with. And that Marble sound could be anything. I'd start by checking the welds on the exhaust heat shields. Most likely under the front seats. I had this same noise and it was usually with a cold engine. Problem was associated with temperature difference between Heat Shield and Exhaust cross member pipe. Noise went away after everything got hot.

 

Now I know what to look for. Thanks.

 

I recommend you don't relay to shops what others say!