I've got the 3.1 in my firebird still. I've just accumulated a new noise...once the car warms up I can hear a very loud very fast rattling noise...I thought it was somthing loose, like a bracket or the exhaust manifold, but nope. While I was looking in the engine bay, thinking something was loose, I realized that the sound was coming from the passenger side cylinder head...I pretty sure...Like I said, it's loud and hard to tell where exactly. So I'm thinking a possible bent valve...what do you guys think? The engine has 160,000 miles on it. I'm the second owner though, so I know it's been taken care of. Thanks for the help guys.

 

Get a fairly long screwdriver and put the point to the engine and the handle end to your ear. Then move it around. Almost as good as a stethoscope or however you spell the dang thing.

 

Actually I have a stethescope....my mom used to be a nurse...lol. The noise is definatly coming from the cylinder head...