CAM24

I've got a new noise this summer, which has never happened before. When I turn on the a/c, something starts rattling underneath the Jeep. It sounds pretty bad, but it doesn't really affect the performance of the Jeep at all. It just sounds like something isn't right under there. I put my head down there but wasn't able to locate it. It sounds like it's coming from right beneath the front seats when sitting in the Jeep, but it's probably coming from the engine bay. I didn't spend a lot of time searching for it because I wanted to see if anyone has had similar issues. Didn't come up with much on the forum. FYI I also have a p.o.s. spark-knocking, oil-burning 3.8, but this noise is only evident at idle.

ronjenx

If turning on the A/C makes the engine vibrate a little more, you could be hearing a rattling piece of heat shield.

CAM24

That's true, but it isn't that tinny kind of sound that a heat shield makes. It sounds more internal.

Rum Runner JK

I hate that heat shield

ronjenx

You are in the best position to troubleshoot it, then. There's no way the degree of rattle can be determined over the internet.

Most times, a rattle underneath has been caused by one of the many heat shields.

CAM24

Yeah I know. I was just hoping that it would be a somewhat common problem that would be immediately identified by the forum. It's always my first, and often the only necessary step of troubleshooting!