DC8808

I have a metallic rattling/sounds like something is hitting the body when I start my car up. it will rattle for a few seconds hen stop, then 20 seconds later or so come back, then when i start driving goes away, and will come back when I shift sometimes. Very odd. shitty GM quality. anyone experienced this?

mrburnout81

iTrader: (8)

get under your car and hit your y-pipe. if it rattles, your cats are breaking up

blitzace12

iTrader: (1)

dont know if this will help but my jack in the spare compartment was loose and gave me the same sound you are discribing... but from rear

DC8808

definetly from engine bay. it will drone on for a few seconds then go away. then come then go just a few times.
Thanks for the info though. I'll tighten up the jack anyways, good to know.

car only has 48k, doubt its the cat, but ill check as well.

antsls1

iTrader: (3)

i have a similar sound from the engine bay/under the front left tire area i keep thinking it is the y pipe but i cant find anything. i do no mine is the exhaust but i just cant track that pesky thing down. good luck with urs post here or pm me if u figure out what it is so i can check mine. i have been trying to trace this sound since sept of last year. on a lift and on jack stands just cant find it.

2000KnightRider

iTrader: (21)

I have a slight metallic grinding noise coming from under the car from what seems around the tranny area/exhaust area. It will start when its first start up or when car is cold and will go away after several miles. I park it for an hour and it comes back, I drive it a few miles back to work and its gone.

NonGoggleGuy

M6 or auto?

In the M6, if it sounds like a quiet knocking (like a very quiet bottom end knock), it might be in your TOB/pressure plate in the transmission.

hitmanws6

iTrader: (20)

mine was doing that after the rebuild. the y pipe was hitting that litte support. took it off and it went away