Would it make any noise? Would there be performance degredation? Could it melt only partially?

I've had cats clog before. However I seem to have a rattle IN my muffler and I was wondering if it could be the CAT or the muffler causing problems? Touching the exhaust, heatshield, etc doesn't seem to change the sound.

With the latest EPA Standards the CEL would must likely precurse the CAT issue prior to it melting. You would see P0420/421 codes as the CAT efficiency degraded.

He'd make alot of noise initially and then just stop meowing altogether. It would be one hell of a mess to clean up.

Somebody had to say it.

The cats in the RX-7 were ceramic, and broke into chunks and clogged up when they died. I *think* the RX-8 uses a metal catalytic converter, which I'm sure can still melt, but is supposedly less likely to break into chunks.

I know there's a TSB/recall about a loose heat shield around the transmission - that might be a possibility.

Dale

The substrate is metal.
The catalyst would melt and run to the back of the cat where is solidifies again and blocks the cat with a wall of brown/gray crap.

It most likely wouldn't rattle.

I had the heatshield done already, this rattle comes during acceleration, and after hard accelleration when I stop it continues to rattle when parked for a little while until it settles down.. the rattle sounds like it's IN the muffler, can stuff get in there and rattle?

i love that hahaha!!

Originally posted by rotarygod
He'd make alot of noise initially and then just stop meowing altogether. It would be one hell of a mess to clean up.

Somebody had to say it.

theres been quite a few cats replaced in the Uk.

Mine is due for replacement asap.

Cat rattles, chips, blocks exhaust , hits performance/ecconomy.

I've had no error codes/warning lights. Picked up on routine check by dealer (who has seen at least 3 others).

How did they pick it up as a bad cat then? My dealer just blames the rattle on the aftermarket exhaust.

Originally posted by RobDickinson
theres been quite a few cats replaced in the Uk.

Mine is due for replacement asap.

Cat rattles, chips, blocks exhaust , hits performance/ecconomy.

I've had no error codes/warning lights. Picked up on routine check by dealer (who has seen at least 3 others).

Originally posted by guy321
How did they pick it up as a bad cat then? My dealer just blames the rattle on the aftermarket exhaust.

Theye were checking for a drivers door rattle (which only happens when cold). And they;d seen several bad cats before.

Usualy (in the UK) there picked up after the pro-drive day (freebie mazda track day) when the car doesnt perform like the others.

I cant hear any rattling from the exauhst but mebee its just me.

Originally posted by guy321
How did they pick it up as a bad cat then? My dealer just blames the rattle on the aftermarket exhaust.

WHICH EXHAUST DO YOU HAVE?

If it is in the muffler, take the muffler off and shake it. Maybe it will rattle then. Alternatively, I guess you could drive around w/ it off and see if you could hear the rattling (if you could hear anything over the exhaust). If that isn't it, pull and replace whatever aftermarket stuff you have with stock stuff, one part at a time, until it stops, then you will have your culprit sitting on your garage floor.

I picked up stethoscope and the noise is definately coming from the exhaust system. I can hear it coming out of the exhaust pipes. Also, any pip that i touch the stethoscope to, I can hear the rattle. I don't hear the rattle on the muffler housing or on the cat housing, so I don't think it's a heat shield..

Any ideas ?

I have the borla

I REMEMBER THERE BEING A RATTLE ASSOCIATED WITH THE BORLA AT FIRST. ONE OF THE HANGERS RATTLES AGAINST PART OF THE FRAME OR SOMETHING. YOU HAVE TO ISOLATE THE ONE THAT IS TOUCHING AND THEN BEND IT SLIGHTLY SO IT WONT RATTLE ANY MORE.

I'll check but it sounds like it's coming from inside the exhaust system not outside.

Originally posted by zoom44
I REMEMBER THERE BEING A RATTLE ASSOCIATED WITH THE BORLA AT FIRST. ONE OF THE HANGERS RATTLES AGAINST PART OF THE FRAME OR SOMETHING. YOU HAVE TO ISOLATE THE ONE THAT IS TOUCHING AND THEN BEND IT SLIGHTLY SO IT WONT RATTLE ANY MORE.

In one of my old cars I lost lost the fire in two of my cyls so I was only running on two. I managed to drive it home (30 miles). I know, shoulda had it towed, but I was young, paying for school, and broke. Anyhow, by the time I made it home my cat was glowing so bright I thought it was going to damage my car. Luckily it didn't. After I had the ingition problem fixed, I had to get a new cat. The one that basically melted rattled like an old tin can with jumping beans in it, and it was also clogged like a mo fo.

Looks like the dealer is willing to check out my cat.. hope that's the problem and they cover it under warranty... it would suck if pieces of it are in my borla cat-back tho..

Anyone want to share rx-8 cat replacement stories?

Also, the exhaust wouldn't cause the cat to break up right? (incase they try to say that) but they seem cordial about it so far!

If pieces of the cat are sitting in my muffler, would it be Mazda's responsibility to replace my borla Exhaust?

I have just had my cat replaced , apparently it melted for some reason and as a result the car was running tlike a dog on 3 legs.
I still have a raspy rattle problem which they ( Eurocar Mazda Artarmon Australia) claim is normal for the car or claim there is no noise , depending on who I talk to.

They were ahppy to replace the cat under warrenty but I am still stuck with a rattle under exceleration.

car is 04 model AT

:mad:

melting cats, mysterious rattles , whats next?

they want me to bring it back in 500-1000km so they can check the cat again to see if its still happending so fingers crossed.

Resurrecting this thread, did anyone ever get to the bottom of what Mazda would do if bits of the cat did end up in an aftermarket muffler?

I ask this because I had a cat replaced around 8000 miles (faulty o2 sensors cause it to degrade super fast) and when they took it out they said great chunks of it just fell away. This being the case, in theory bits could come out and lodge in the muffler.

In the TSB about flooding / replacing the cat, it does say to also replace the muffler.

I'm just worried that if in the longer term / should my car flood / there is an ongoing cat failure problem, then it could end up with crap in my Borla, who would replace it?