Ditch the cat???....

[deftdrummer]

hey everyone here's the situation; Ive been noticing this noise lately from my exhaust within the last week that sounds like a real loud rattle while driving at any speeds. I have a cat back exhaust so no head shields there, and i took off the other heat shield above the cat to try to take care of the rattle but it didn't.

I am thinking that i need a new cat since that is exactly where the noise is coming from. It sounds like metal clinging around in there.

So anyways, i dont have the money right now for the cat and i was thinking about removing the cat to see if that takes care of the problem. I really liked the way it sounded really cool when i started it up with the exhaust off (from cat back) before.

My question is this (finally): besides the fact that it's not legal to drive around without a cat because its loud and emissions go through the roof, will it start smoking dark black smoke from out under the car too?? I heard from someone driving without a cat or exhaust for that matter. Is this true??

[Bandit240]

No it wont smoke. As of right now my 240 has a gutted cat and only half its exhaust on. sounds great but rumbles my ***. And if you live in CA forget taking it off or gutting it. Just find another one.

[Onizuka]

does it rattle when you rev it in neutral?

[deftdrummer]

oh ya it rattles like a mofo. And by the way, to recap on things. Im only taking the cat off to see if that's EXACTLY what is causing my rattle. Im not doing it for performance or any crap like that. I plan on replacing the cat and the header making it a full effecient exhaust system. But I just didn't want to drive around for a little bit with black smoke coming out.

[Onizuka]

wierd, it sounds exactly like the standard heatsheild problem. Maybe one of the filiments inside of the cat came lose or something. Either way if you relace your cat and it doesn't fix the rattle you'll get better emissions next time you go in for testing

If you bottomed out lately you may have bent your whole exaust which is solid mounted to the engine. The bend may have moved the whole exaust closer to the car body so it hits it when the engine moves (which it does easilyse of the crappy stock mounts)

if i can think of anything else ill post it later

-matt

[Sliding_S14]

Ive heard of somthing simular to this it wasnt on a 240 but believe the mechanic was saying there was a piece of carbon rattling around in the cat. I didnt see exactly what was in side of it just heard it as he drove by. not sure if thats whats wrong with your cat but he mentioned it had to be replaced. Like i said not certain if it was a piece of carbon could have been a few things that got inside and rattled around. good luck.

[deftdrummer]

Ive heard of somthing simular to this it wasnt on a 240 but believe the mechanic was saying there was a piece of carbon rattling around in the cat. I didnt see exactly what was in side of it just heard it as he drove by. not sure if thats whats wrong with your cat but he mentioned it had to be replaced. Like i said not certain if it was a piece of carbon could have been a few things that got inside and rattled around. good luck.

yeah i thought it was that too at first, or maybe a piece of the glass and crap thats in the cat but since its hollow that doesn't leave much. Aside from taking it off and holding it upside down so the crap could fall out (not really anything in there) I sanded down both flanges on the cat and the down pipe and got 2 new gaskets. That seems to have fixed the exhaust leak noise quite well. While i was down there i took off the upper head shield actually ABOVE the exhaust. It looks like a big tray or something. That took care of another rattle, but there is still one more i can't quite find. Its ok though cause its not bad enough for me to care about really.