Rattling exhaust @ idle.
 

Hi there,

Anyone have any clues why my exhaust rattles when stopped at traffic lights. It makes a pop sound, or sometimes a tick,tick,tick......vibrating sound OR sometimes it doesnt happen at all. Could it possibly be a clogged cat? Any help would be great.

Thanks,
Geoff

can you be more specific...does the sound come from the back? under the car? engine bay?

The back, thanks for fast reply.

Cat is breaking up.....

Meaning its most likely clogged?

Put it up on a lifit and check it out.

Heat shield, bad exhaust gasket, etc...........

No, I mean literally breaking up. The cat is a ceramic honeycomb. The ceramic is broken. Little pieces knock around in the connector pipe causing random noise. If you can get it up on a lift, disconnect the pipe between the cat and muffler, tap it with a rubber mallot and pieces of your cat will fall out...The cat is under warranty for like 80 or 100k. The problem with a broken up cat is that little pieces are going to lodge in the muffler. Mazda replaced both the muffler and cat on my 8.

Thanks alot guys, will explain to mazda and hopefully get a quick fix.