Will a rattling cat converter kill an engine?
 

The converter is rattling when the car accelerates, the mechanic says the metal is shattered inside the pipe. I don't mind having the noise as I can't hear anything inside the car, but he warned me that the pieces might get sucked into the cylinders that might kill the engine :suspicious:

Not sure if he is being serious, I never heard air will flow backward into the cylinders. The car passes aircare, is there a quick and cheap way to stop it?

for what car is this? maybe there is a cheap universal you can get from lordco or sth.

my only bad experience with a busted cat was one blocked with chunks of carbon deposits in a vw gti. the o2 sensor started getting bad signals and made the engine run like crap, and then the cat itself overheated and died :(

MB W220, there are 4 cats there, I don't know which one needs to be replaced.

People say use hammer, will it get even worse?

have you tried the MB message boards?

i don't know about hammering it. it will break up any blockage inside, but i'm guessing it will break everything else also.

some generic reading about cats:

AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Catalytic Converter Problems

Well it might, but it is not likely. The catalytic convertor is a mesh of precious materials. It is more likely that more bits will fall off and block the convertor completely, causing the whole matrix to melt.

Depending on how the car was driven and maintained, in HK there will be a lot of stop and go traffic, so carbon will have built up. Big wheels / stiff suspension transmit more force to smaller bits, don't be surprised if something else rattles loose too.

It is an old car. Drive till it dies... get another one.. rinse, repeat.

Sounds like you need to find a new mechanic.

yeah you need a new mechanic.

Rubber mallet and listen for rattles, if its a secondary cat just weld in a straight pipe, it wont sound very different, just a little more throaty.

Get a new mechanic, very soon you will be hearing about how a burnt out headlamp will cause ecu failure.

^
i lol'd pretty hard there

Cats can damage engines if they break apart. They can also damage turbos. I've replaced numerous turbos on 335's because of a failed cat (breaking up into little pieces).

At certain engine RPM's and load you can have resonance in the exhaust where for a brief time exhaust flow can be reversed. Though I doubt pieces of a cat could make it all the way back to the exhaust valves. On many turbo cars, however, the cats are placed in very close proximity to the turbo outlet, so the chances of cat pieces damaging the turbo are much higher.

Yes it is possible and the closer to the engine the cats are the more likely. Now even if the material doesnt cause the damage a partial blockage can lead to over heating and potential engine damage. If your cats are fucked just replace them. If your mechanic wants to charge you too much get a second opinion but dont ignore the issue.