Well, i think i may adress this now. Whenever i drive my '91 Ex, i hear this noise that, from further investigation, sounds like grinding coming from my exhaust manifold. It varies in how loud it is, it is starting to scare me. It only does it when is runs around 2400 to 3k rpm's. I have no clue what it is. At first i thought it was a tensioner pulley... but i didn't see one. and the sound, like i said, is coming from the manifold. any clues on what it could be?

 

the gasket? is your engine turning black? the manifold cover? the cat? make sure no two metal parts are bumping w/ each other...

 

A friend said i sounds like an exhaust rattle... which would make sense b/c it's sounds like it's coming right from the manifold... but then he said heat sheild and i don't have one. but no the motor is clean. only a couple of remote places have grease on them. but nothing anywhere the sound is. to be honest it might be the manifold. it looks like it's been through hell and then was put back on. no holes but on the rebuild it had, the guy that did it maybe didn't use new gaskests for that?