What are tell tail signs of a cat going bad? with out getting an emissions test...Thanks

 

When mine went bad, My car would not rev as easy as before, you will notice a little bit of a smell that in my mind is the "burning cat smell". You will also notice lots of power loss.

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1987 Firebird Formula
305 LG-4
GM Vortec heads 2.02x1.6 valves
Crane CompuCam 2030
700-R4 Trans
4 barrel quadrajunk remained by holley (this carb stinks!!!)
edelbrock performer intake
Hypertech Thermomaster Chip
Open Element Air Filter
No Cat with Straight pipe (Dynomax muffler rusted apart and fell off probably could not stand the heat )
Accel H/P Coil

- Soon to be installed
383 stroker (built and ready)
NO MORE COMPUTER CRAP
700R4 Lockup kit
Edelbrock TES
True Dual exhaust or 4 inch single pipe to dual 2 1/4"
Stall convertor

 

It will probably also rattle when shaken. The smell comes from a rich mixture that results from no airflow(clogged cat). Your cat is full of grids that will break over too many years of impact. This is what cloggs it up.

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'87 Bird 350 .060 over 700R4 + Lots more

 

ATOMONKEY,
When the cat goes bad (begins to rattle) can it also cause the engine to run hot?

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'84Z28/'92 305TPI
'92 complete rear suspension/PBR disc/Posi/3:42
Light weight 34.5mm stabilizer bar in front ($10 from wrecking yard)/
"wonder Bar" ($5 from wrecking yard)
23mm sta. bar in rear
Rear RS Springs (slightly softer than my Z28)
comp cam, flowmaster
TB coolantbypass/shutoff valve to heater core
powersteering cooler lines (liberated from another wrecked car of course)
MAT relocated
Ram-Air(home-made) gutted air-box
IROC ground effects/wheels GY245/50's
700R4 superior shift kit/ corvette servo(excellent shift kit btw)
home-made strut tower brace (cost $6)

Rebuilt engine and transplanted it myself.

Love this engine!

freshly painted OCT. 2000 Teal with two white stripes on the hood and deck lid

LOW performance people should drive low performance vehicles!

 

if the exhaust cannot escape as fast, heat will build up and cause overheating, but I think only to a minor degree.