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I am getting a lot of unflattering noise from my exhaust. I have stock Manifolds w/ cat, 2.5" in exhaust with x-pipe. LT1 engine.

Does anyone know what a bad catalytic converter sounds like? does it have a distinct sound I need to be listening for? I ask because I currently hear a sizzle from under the car, almost like water on really hot metal. The sound is off an on but fairly consistent and fairly annoying.

I was told about 6 months ago I had a Catalytic Converter going bad. I live in CA so I must replace. But I don't want to if a bad cat isn't the cause of the noise.

Any help, would be appreciated.

Thanks

Travis
 

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Yes my Caprice has a rattling noise at the left side exhaust, it is the Cat. It's also starting to stink at startups
 

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......I currently hear a sizzle from under the car, almost like water on really hot metal......
Probable water dripping onto really hot metal. You know.....looks like a duck, walks like a duck, quacks like a duck......must be a duck. Maybe AC condensation finding it way to the pipes of your exhaust system.

As for the cat going bad......cats going bad usually = 1 of 2 things.

1. Cat will clog and exhaust flow will be stifled......since you have an X-pipe, you can't check to see if flow from pipes are at least close to equal. BUT, the restriction in the flow will likely cause the exhaust manifold from the same side to get REALLY hot. Run the car at night until hot and pop the hood to see if either manifold is glowing red...... No particular sound is associated with this.

2. The innerds of the cat will break-up and will rattle throughout the exhaust system.....in which case you'll hear......well......rattling. Oh yeah......your exhaust gases will start smelling pretty darn strong......and bad.

Best of luck!!

KW
 

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When mine plugged up, the exhaust manifold on that side was significantly hotter than the other. That is pretty much a dead give away. You can look for a sound, loss of power, etc but the heat is the easiest way to tell from my experience.

I knocked one out (already had a tune w/ 95 ECU) when it plugged up and just didn't feel like messing with the other at the time and never got around to other one until it plugged up. When that happened I purchased export pipes, I live in Oklahoma where there isn't any emission checks but either from age or not fixing the cat right away I also had leaks in/around my exhaust manifold. So instead of jacking with the thing anymore I bought BBK headers and now she sounds great. Helped the gas mileage too, obviously. ;)
 
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