A while back i had a loud clanging/rattle type noise comeing from the lower passenger side of my 02 Z28, car was still under warrenty back then so i took it in and they said a heat shield by the tranny had come loose..... well 4 months later (07/25/05) the noise came back but i didnt realize what it was at first, figures cars warrenty ran out last month, but anyway i stopped somewhere and shut the car off, came back like a minute later and started it up and the noise was deafening, and i started heading towards home and it had a lod steady rattle then it went like POP POP POP POP POP POP and the noise quit. the pops where extremly loud. i circled around and scanned the road to see if anything had fallen off and saw nothing. i should also note the the past couple of months it made a slight bang noise when it first turns over when its cold. i figured it was the new bolt on exhaust banging from the initial shake on start up. anybody have any clue what it is thats rattling? it doesnt do it anymore except for when i accelerate rapidly but cruising its fine. any answers will help.

 

So you mentioned you have a new bolt on exhaust...is it just a catback or also a new Y-pipe. I recently installed a new Random Tech Y-pipe on my 96Z28 and had some crazy rattling. Not sure what your 02 exhaust looks like from the bottom, but the LT1 y-pipes are 2-piece....main part is from the passenger side to exhaust...second part is from the driver side to mate with the main part. In my case, the flanges that mate the driver side and passenger side pipes was touching some transmission cooling lines. I just had to loosen this flange, and rotate it away from the interference.

Next time your under your car, just bang on you exhaust (don't damage it of course) and see if you can pinpoint where the vibration is happening. Understand that during idle and cruising, your exhaust systems probably vibrating like crazy..just hopefully, nothing's close to it that could make noise.

 

get under the car with a rubber mallet. Bang on stuff until you find the noise.

I had a rattle in my cat that I found this way. found the rattle, fixe3d it and all is well now.

You can use your fist to hit stuff, but you will begin to hurt your fist after a few dozen hits. The rubber mallet makes it much less painful!

 

Come'on...be a man...hit it with your fist. Better yet, use your forehead...just make sure the "ringing" you hear is from the car not your head.

 

i had the same thing happen to me; it was the heat shield on my catalytic converter. i was going to pull it off, but it happened to fall off in my driveway one day. I think that catcos are known for that- if thats what you have.

 

Fix it with an ORY