Ok, I have a 2000 Civic EX - Automatic. About 2 weeks ago it started making a loud metal vibration / rattle noise at around 1200 RPMS and between 2300-2800 RPMS. It does it all the time, hot or cold, accelerating or decelerating. The cars behavior is still spot on...no issues at any speed or anything else that indicates a mechanical issue.

Anyone have any ideas of common things to check? Thanks for the help!

 

sounds like it could be an exhaust heat shield rattling check under ur car for loose heat shields either remove or tighten whichever floats ur boat

 

Yeah, as Josh says, loose or damaged heat shields are very common sources of this type of noise.

If the heat shields are fine, however, check whether the header, exhaust pipe A, or the cat is producing the noise. In particular, exhaust pipe A and the cat have internal parts that may break loose and cause rattling noises.

 

I'll hope for the heat shield then. I'll check tonight when I get home and report back. Thanks!

 

heat shield or broken tabs

 

Ok, checked it out last night and the heat shield wasn't noticeably lose. I just sort of tapped around to see if I could find something to make a nasty noise when I tapped it. Nothing really. But there was a 2nd heat shield over the exhaust pipe in the middle of the car. It seemed to be bend down and touching the pipe...I pushed it up just a bit (bent it up). Really didn't expect that to do anything...yet the noise seems to be gone.

How would something like that get bent into the wrong position?

 

maybe it was hit by a rock.