catalytic converter?

[beat88ls]

Originally Posted by silicon212

I've had more problems with those old beaded cats, the ones 'j cAT' states last forever, getting plugged. Perhaps I am an anomaly, perhaps not. Either way, the beaded cats are very restrictive by design, where the monolithic, honeycomb ones of newer design are much less so.

A very rich running engine can kill a cat (as well as the 02 sensor). Likewise, an engine with a chronic misfire can kill a cat. Both due to overheating as the unburned hydrocarbons burn inside the cat.

If you have a simple carbon buildup, a good, hard run can 'bake' the cat and remove the restriction.

did the newer cats from the early 80s still come with Platinum in them? i have to change out the cat in my 83. not because it has died, but because the flange has rotted off the end that meets the intermediate pipe.

[silicon212]

Platinum and palladium are the catalyst metals, so yes- they all have them. Plus, the dual stage cats (mandated from 1979 onward) have rhodium also, to control NOx.

[j cAT]

Originally Posted by silicon212

My 1982 Impala had the honeycomb cat in it. If you had an '83 with the octagon cat, it was retrofitted. Regulations enacted in 1979 effectively ended the older beaded cat - for lack of NOx control.

I have seen regional differences with vehicle emissions....this is pehaps why your 82 and the 1979 regulations you mention caused my vehicle to have the older much larger cat...while yours had the honeycomb...

In any case with GM vehicles built at that time these smaller cats were plug prone.... 60-80,ooomi and they plug up...this is with the 1980's models ...later the cat improved and only if you had some failure that caused a poor engine operation would you have issues with this part...

my 1983 was built in may 1983..

[j cAT]

Originally Posted by beat88ls

did the newer cats from the early 80s still come with Platinum in them? i have to change out the cat in my 83. not because it has died, but because the flange has rotted off the end that meets the intermediate pipe.

this can be repaired...do not replace the cat ...I did this many times....parts are available to clamp on to the weld remains on the cat pipe you then mount your new flange replacement part two pieces and two bolts....I used s/steel bolts so when this need replacement again it come off easy.....double nut the new flange hardware...

[bhw33191]

Originally Posted by beat88ls

did the newer cats from the early 80s still come with Platinum in them? i have to change out the cat in my 83. not because it has died, but because the flange has rotted off the end that meets the intermediate pipe.

yeah my flange is rotted too.

[bhw33191]

i'm getting rid of the cat altogether because they don't check emissions on my car because of its age.

[j cAT]

Originally Posted by bhw33191

i'm getting rid of the cat altogether because they don't check emissions on my car because of its age.

the removal even though not emission tested may be a violation of law ...so you should not advertise your intentions..

[bhw33191]

Originally Posted by j cAT

the removal even though not emission tested may be a violation of law ...so you should not advertise your intentions..

well in that case "i'm keeping the cat"

[PMack74]

If you change the cat yourself DO NOT simply throw it away! I changed the cat on my 84 myself about 2 months ago. The "universal" cat, clamps, and extension pipes cost me about $110. I took the old cat to a scrap metal yard and got $60 bucks cash. I have been told that the older flat cats are worth even more.

[bhw33191]

Originally Posted by PMack74

If you change the cat yourself DO NOT simply throw it away! I changed the cat on my 84 myself about 2 months ago. The "universal" cat, clamps, and extension pipes cost me about $110. I took the old cat to a scrap metal yard and got $60 bucks cash. I have been told that the older flat cats are worth even more.

Thats definately good to know!

[silicon212]

Originally Posted by j cAT

I have seen regional differences with vehicle emissions....this is pehaps why your 82 and the 1979 regulations you mention caused my vehicle to have the older much larger cat...while yours had the honeycomb...

In any case with GM vehicles built at that time these smaller cats were plug prone.... 60-80,ooomi and they plug up...this is with the 1980's models ...later the cat improved and only if you had some failure that caused a poor engine operation would you have issues with this part...

my 1983 was built in may 1983..

Perhaps your car was built in Canada for the Canadian market.

If the VIN starts with a '2', it's Canadian manufactured.

The 1979 cat change was a federal mandate, so it should have been an across the board thing. CA was a year earlier in 1978.

[bhw33191]

Originally Posted by silicon212

Perhaps your car was built in Canada for the Canadian market.

If the VIN starts with a '2', it's Canadian manufactured.

The 1979 cat change was a federal mandate, so it should have been an across the board thing. CA was a year earlier in 1978.

My caprice says it was built in canada, haven't noticed the "2" in the vin but i'll check.

[beat88ls]

i have an inspection coming up and had to replace the cat because it was rotted and leaked (yeah j cAt it had to be replaced ) after replacing it the car started running terrible. the car chugs after being warmed up and today i am getting a strong odor of sulfur. i have had a service engine light for a while now, i finally pulled the codes today. i got a code 15 which is engine temp sensor... which is not connected (corroded wire) if i remember right this will cause the comp to make the engine run rich, could this be causing the sulfur smell too? its an 83 with 305

[j cAT]

Originally Posted by beat88ls

i have an inspection coming up and had to replace the cat because it was rotted and leaked (yeah j cAt it had to be replaced ) after replacing it the car started running terrible. the car chugs after being warmed up and today i am getting a strong odor of sulfur. i have had a service engine light for a while now, i finally pulled the codes today. i got a code 15 which is engine temp sensor... which is not connected (corroded wire) if i remember right this will cause the comp to make the engine run rich, could this be causing the sulfur smell too? its an 83 with 305

the temp sensor should be connected and this will then cause the computer to work the engine in closed loop mode so that it will respond correctly ...

upon installing a new cat to an old vehicle this can be dangerous as the new cat being very effecient will generate a tremendious amount of heat [glowing red] and cause your vehicle to catch on fire...If the mixture/exhaust is very much loaded with unburned fuel....

Installing any new exhaust part will smell as oils burn off..


perhaps the O2 sensor was damaged with the cat replacement or they disconnected something...


one thing you must check is the heat riser this is at the exteme end/output of the exhaust manifold make sure this is fully open and if they broke it or is rotten use stainless wire to keep it forced open this will cause a problem like yours also...