MikeWS6

I noticed a few weeks ago a very loud rattle coming from inside the drivers side cat. I was about to fix it and then the noise suddenly went away. Now if I really listen for it I can only hear it sometimes at idle. Whats going on? :shrug:

Darkman

iTrader: (2)

Assuming the rattle was not just something loose on the exhaust system, it sounds like the some of the cat internals melted, eventually broke off and passed out of the system with the exhaust gases.

MikeWS6

What is actually inside a high flow cat? I thought they were pretty much empty.

TImmy_Jones

iTrader: (4)

There is still some catalyzing material in there - what kind of cat is it? I highly doubt it melted and fell out...they are made for high HP applications. I would guess a loose bolt or exhaust just barely rubbing somewhere on the car and rattling. It sucks and is going to be very hard to track down.

Best of luck.

Darkman

iTrader: (2)

They do make some fake cats that are in fact, empty. Other high-flow cats are in fact still functional converters and are therefore subject to damage from incorrect fuel mixtures and age. I have Random Tech cats that are legal replacements in most states. (California only allows OEM cats regardless of quality.)

99Bluz28

iTrader: (35)

You have the ceramic core cats. (oem), and metal matrix core cats.. The ceramic core cats. are the ones the are most likely for the core to break into pieces, especially if it receives any type of hard impact. An exhaust leaks or a bad O2 sensor will overheat and burn up a cat in no time.

MikeWS6

magnaflow cats. noise is gone lol