Symptoms of a bad cat?

[JeepMaz]

I've got a '98 Cherokee Classic, 4.0L, automatic transmission. I've noticed over the last few weeks my minor exhaust rattle has gotten worse. Nothing underneath appears to be loose...all brackets/hangers are intact and not rusted too bad. During my last oil change, the mechanic called me over and shook my catalytic converter a little, and noticed it kinda sounded like gravel inside. Is this what a bad cat sounds like, or is the shop just trying to make a buck? I'm averaging 21-22 mpg right now (mostly highway miles), and I always figured a bad cat would lead to worse fuel economy. I have noticed my center console is getting pretty warm lately, figured this might be another symptom.

Next question: ballpark, how much should a new cat cost installed at a muffler shop? I was quoted $185 for a universal fit. Good deal or rip off?

Thanks for the help!

Chris

[Lonestar]

The material inside a cat is a solid honeycomb grid. Sometimes it breaks into smaller pieces and rattles around. Your mechanic is telling the truth, you should replace it.

$185 sounds about right. You might be able to shop around and find it a little cheaper.

[ebxjbob]

Yeah thats legit, mine sounded like that and i said the hell with it. I was on a 300+ mile highway trip at 80-85 and it started smoking real bad...I only had the idiot light cluster and at that point and it was so bad I thought my engine had shit the bed, it was just the cat smoking. Had to do the rest of the trip and home at 55-60.

[90xj06]

let me go shake fluffy my cat and see if she rattles. hehe... lol

yes that would be the sound. have "cough" gutted the cats on one of ny cars. and when that stuff brakes it makes a nice rattle.

[scarface]

Mine used to rattle something fierce on startup... Changed the CAT out and now she purs like a kitten, well a loud kitten

when we took the CAT off and shook it, you could both feel and hear the honey comb just ratteling around.

$185 sounds about right, but you should ask around just to make sure.

[92DripCherokee]

any rattling sounds from a honeycomb brick type cat converter mean replacement. If the catalyst brick shatters, the flow rate goes down, and heat builds up.

I doubt you have an infamous pellet type converter.

if you replace the cat, a new upstream o2 sensor is good idea. if the engine is running rich from an old, fouled o2, it could melt the new catalyst.

[mikejwil]

You can get a direct-fit MagnaFlow from summitracing.com for $92.95... I guess they are all pretty much the same though. How much are they figuring in for the installation?

[Fish'nCarz]

Any cat that ain't dead?

Sorry. It needed to be said.

[djblade311]

symptoms of a bad cat:

- claw marks on your leather couch
- speaker covers look like fishnets
- cat litter all over the place

har har.

[clean96XJ]

Hey

It might cost nothing. I just recieved a recall notice for the Catalytic Converter. Check it out.