Well recently I have noticed that when I start my car up there seems to be an exhaust rattle underneath my car. It appears to be eminanting from my cat. WTF? I have no other symptoms of having a bad cat. My car is getting 22mpg city, and there is no tell tale smell either. BTW 87 2.8 w/ 5speed.

Anythoughts as to whether the cat is going bad, or if it is just loose?

thanks for your help

Kyle

The heat shield on the cat rusts then gets loose to cause a rattle.

Is it like a buzz that sounds like a bad cat? I'll have to check it out.
thanks I didnt even think about that

Get under the car and tap around on the exhaust system with a rubber mallet until you replicate the sound. The cat is about 8" from your butt when you're driving so it is the prime culprit.

JazzMan

The cat in my '85 sounds like it's full of BBs. Tapping with a rubber mallet (as JazzMan suggests) revealed that the noise was indeed coming from the cat.

I don't drive the '85 too much so I haven't gotten around to replacing it, but it's a good idea to do so. If that stuff gets loose then you have to replace the muffler as well.

Ed

Heatshield or guts.

Had a Jeep with a bad cat, guts rattling around inside. Going down the highway at 55, I suddenly lost power under throttle. Had to dive onto the shoulder and creep along at whatever minimum throttle I could give 'er, around 15mph. Not fun.

The honeycomb inside the cat had broken up and jammed up the exhaust.

My cat heatshields were only held on by one spot weld left and i got tired of hearing them so i just ripped them off. ive had noo ill effects so far. and the G/F at the time liked the "quieter" car

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'86 Fiero GT
My Fiero XoticRydz Mid-Rear Madness
I am the signature virus, please put me in your signature so I can spread
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The heat shield is the most likely rattle. rip it off and toss in the trash.
Don

The heat shields on the exhaust, in the engine compartment were rattling sometimes on mine.
I removed them with no ill effects.

quote Originally posted by zMacK: The heat shields on the exhaust, in the engine compartment were rattling sometimes on mine. I removed them with no ill effects.

This is definantly eminating from under the body of the car where the cat is situated. As soon as I get time I am gunna see if it's the heat shield or the cat going bad. It doesn't really bother me all that much though.