So my cat converted went bad and the dealer replaced with a new cat but now the new cat makes an awful rattling noise.

When I asked they said it's some loose pebbles in the cat and it should blow out. However it has been 2 weeks and it still makes the sound.

Any thoughts.

 

They are smoking crack. Either the heat shield is loose, hanger is not properly seated in the bushing, loose or missing nuts/bolts, installed without the gaskets, or they gave you a faulty Cat-converter(broken internal packing or resonator). Have them look over the whole exhaust system and since they mentione that there are "loose pebbles in the cat and should blow out", you might as well complain and be concerned about your engine...

 

That is not normal, it may be a defective cat converter. Have the dealer fix it or replace it...if i were you, plus there should be a warranty on it.

 

Ok looks like the old cat parts were stuck in the exhaust system. I took it back and they took care of it. No more rattling noises for me. Yay!