sounds like a metal fan clipping something?
a marble bouncing around?



90% of the time its the catalytic converter! almost payed some one a grand to do a rebuild because the mechanic was a theiving bastard.
then he tried to say it was also my flywheel and wanted another 800 to fix it! NEEDLES to say hes no longer touching my car.

heres how to know for sure!

1. wait until the car cools down
2. jack it up
3. knock on your catalytic converters fairly hard and if you hear a rattling inside its your cat. problem solved pay a welder and buy a new cat! boom done!
you just saved 900 bucks!