The factory catalytic converter filler hole plugs on two of my Fieros corroded and failed.
On my '84 SE, the converter was replaced 15 years ago with a much more compact unit; it's still fine.
On my '86 2.5L coupe, the original plug started leaking a few days ago. I found out today that a commercial plug is available. A lot cheaper than replacing the converter...
Even tho cat work perfect like that... Depending how your and other areas does safety/emission inspections, the plug might not pass. Inspector can treat the plug = any mod on the cat is auto failure.
In NY, they lift up the car to inspect and plug cat = fail inspection at most places. Other places don't bother looking, just use tailpipe testing.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
The chemical reaction slowly uses up the metals inside....usually they fall apart and rattle around in there. Mine did that at about 90K miles. It's a honeycomb structure.
The chemical reaction slowly uses up the metals inside....usually they fall apart and rattle around in there. Mine did that at about 90K miles. It's a honeycomb structure.
I'm pretty sure it does not. The only thing that causes a catalytic converter to fail is physical damage or poisoning. There is no consumption - the platinum coating accelerates the oxidation of HCs to CO2 and water. The rhodium coating breaks down NOx emissions to N and O. Free O (either stored or present in the stream) combines with CO to produce CO2. Each coasting acts only as an accelerating agent (a catalyst) to provide a suitably quick reaction as exhaust gasses flow through the converter. Excess heat can melt the substrate and pollutants in the exhaust (oil, sulphur, etc.) can coat the substrate, but nothing in the chemical reaction results in loss. All the thing does is shift electrons around via redox.
The cross section in the factory manual shows a core of catalyst beads suspended in a mesh enclosure. If beads come out of the plug opening, I wonder if the enclosure has been compromised and the gases aren't all flowing through the package of beads...
I think (but don't know) the reason you have those plugs is because that's how the catalytic converter is filled initially. On modern cats, where the catalyst is "dusted" onto a honeycomb substrate you don't have those plugs - the shell is formed around the substrate. It makes me think the plugs and the beads are related. If a plug fails and the beads come out, what's probably happened is you've lost some catalyzing capacity, but without knowing relative volumes it'd be tough to guess how much. It's definitely possible some empty space has been created exhaust will favor that path.
I'm pretty sure it does not. All the thing does is shift electrons around via redox.
I should have taken pictures.... I was looking at what I thought was an original 88 cat cut open...and it was honeycomb, with about half of it eroded away to nothing, and the other half lying in pieces. Maybe heat did it, or perhaps some other odd chemical...but it was not going to do it's job, and needed replacement. Descriptions I have read say that converters don't last forever, with most suggesting and average age of 100,000 miles.
Originally posted by Gall757: I should have taken pictures.... I was looking at what I thought was an original 88 cat cut open...and it was honeycomb, with about half of it eroded away to nothing, and the other half lying in pieces. Maybe heat did it, or perhaps some other odd chemical...but it was not going to do it's job, and needed replacement. Descriptions I have read say that converters don't last forever, with most suggesting and average age of 100,000 miles.
I don't have a clue when manufacturers started switching from bead-style cats to monolith-style cats - it could very well have been in the '80s, and with a manufacturer as large as GM it could take years to switch all assembly lines from one to the other... who knows how companies that big stockpile parts! An '88 could certainly have a substrate cat from the factory.
What you saw on that car was the result of physical damage. The substrate had failed either due to trauma or heat - roughly the same thing happened on my old Trans Am - I found half the substrate rattling around in the muffler. I had a hilarious problem on my Saab 9000 - radiator hose sprung a leak and hosed down the distributor which resulted in a loss of spark. A mountain of fuel got dumped into the exhaust unburned and kersploded in the catalytic converter. That car had a straight-through Dynomax muffler on a 3" exhaust, and with nothing to get in the way I blew the cat's entire substrate out onto the road behind me. It was dark, and the flaming mess just littered two lanes of the highway. Fortunately nobody was around and it was funny and not scary.
The substrate (and the beads) are just there to hold the catalyst. The part that does the work is the coating on the ceramic substrate or beads, and it is not consumed in the process. If the ceramic isn't damaged by trauma or heat, the unit will work forever. My '85 Volvo 745t was sold in 2004 with 240,000 miles on it, with its original cat and still flying through California smog. My XR4Ti's lasted 250,000 miles before it failed. It's a matter of maintenance and some luck... If your engine doesn't start burning oil and you don't accidentally get bad fuel (with high sulphur, for example) your cat should never need replacing. That is also why used cats are actually worth a fair amount of money - if they are not damaged but just contaminated, they can be cleaned and sold as remans. The expensive parts don't go anywhere, they just become inaccessible.
Of course, the chance of most cars getting that kind of looking after is pretty low, so a 100k replacement interval could certainly be typical. I know, for example, VW put insufficiently-sized cats on a lot of their early PZEV cars and as the cars aged, there simply wasn't enough material withstand contamination from normal engine wear. A LOT of them got replaced under the mandated California 10-year warranty.
I'm as cheap frugal as they come, and repairing a decrepit old original catalytic converter is not something that even I'd bother doing.
A brand new replacement cat can be bought on eBay for next to nothing.
I guess I'm cheaper frugaler. Or lazier...
The converter itself is in good condition; only the plug had failed. The racket was annoying. I didn't want to have a clamp-on style, so I'd have to have a shop weld one in. I wouldn't bother with a used one (which I have already and could have cut and clamped in).
I asked for a patch to be stainless welded over the hole. The shop had a plug specifically for those converters. 20 minutes at the shop; $45.20 including HST for peace and quiet. Good deal, I think...
Rock Auto has converters for $122.53. I checked Ebay, starting at highest price for fun... No wonder I don't have a Ferrari...
I have no idea about the frequency of inspections in Canada but you can always buy the Fiero Stores aluminum headpipes for $40 and have a shop weld on a flange on both the new pipe and the catalyst pipe and interchange the 2 between inspections. Then you would have a cat that lasts the life of the car.....or you
Yes, Top post shows "Bead type" of cat. The Plug is how the beads go in. Bad plug causing to loosing beads are a problem. You need to test the exhaust to see if the cat still works.
Bead cats are bigger in size vs most "brick/honeycomb" types. If Fiero V6 uses a brick was likely because of space.
In days long passed... Was kits so Shops, maybe a DIY, can replace the beads but I don't know anyone carries them.
Is cheaper to replace old bead cats w/ brick for Federal use. CA rules make cat are more expensive and likely illegal to refill old bead type cat. Of note... Old cats uses allot more platinum then new ones. This is why new Federal cats are cheap. They found why to make them using less rare earth metals but still doing same job.
thesameguy is correct... "The only thing that causes a catalytic converter to fail is physical damage or poisoning." Most Catalyst failures are a symptom of engine problems. Exception is Bead Type can wear out the beads from hitting each other over time. Enough bead "shrink" you can loose catalyst down the exhaust. How fast/slow can depend in many things. My catalyst is OE Bead and ~220,000 miles and still passed 2013 DE emission. Getting ready to go to 2015 inspection.
Warnings: Poison cats can over heat the medium and can kill them but worse overheating can cause a fire. Overheat for any reason can make the case temp easy reach 1500°F or more. "Burning" coolant from bad seals/gaskets and phosphorus from High ZDDP oils can poison them. Just Burning a little bit oil and/or running engine Rich can overheat and kill them too.
[This message has been edited by theogre (edited 04-02-2015).]
I asked for a patch to be stainless welded over the hole. The shop had a plug specifically for those converters. 20 minutes at the shop; $45.20 including HST for peace and quiet. Good deal, I think...
I bought a brand new cat off eBay for my duke four years ago. Cost me a grand total of $20... which included shipping!
I acquired an '88 Formula last July which still had the original cat on it. Needless to say, the cat was not functional any longer. Picked up a brand new cat for the Formula off eBay for $33 (including shipping).
Let me answer the questions and non questions in this thread. The V6 Fieros use the honeycomb cats, the dukes use the beads. If you have the bead type I can almost guaranty it is not full, what happens to the beads is they get broke up and go through the small holes designed to hold them back, usually end up in the muffler. Sometimes the honeycomb also gets broke up and in the muffler. This is coming from me cutting off over 100 cats off of Fieros, The bead type about 80% were empty, only one had about 75-80% left, the others were less than half. The honeycomb faired better as some were still intact, some had part of it broken up, and some were just empty too. If you have the bead type i would just replace it. New cats are cheap as they found a way to use less platinum, palladium and rhodium IE thinner plating than stock cats do. Around here you can get a new cat for like $80 INSTALLED. BTW it is also illegal to sell a used cat for anything other than scrap. Just FYI
I bought a brand new cat off eBay for my duke four years ago. Cost me a grand total of $20... which included shipping!
I acquired an '88 Formula last July which still had the original cat on it. Needless to say, the cat was not functional any longer. Picked up a brand new cat for the Formula off eBay for $33 (including shipping).
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Yikes! I just read the HERE thread... Baffling to me really, why people choose to be confrontational so frequently.
Anyway, I'm an amateur welder and not confident that I could weld a cat in. I prefer a welded together system to a clamped together system, so an exhaust shop would get the business. The plug was a quick, made for the issue repair on an otherwise solid system. The leak didn't merit any of my time cutting and clamping something else. I anticipate many more years of service, but time will tell.
All the emission tests I've ever had in the Fieros have been so far below the allowed limits it's laughable. I know some of the beads escaped, but there's no noticeable change in the exhaust odour like a non-cat system apparently produces. Hopefully, it's still ok.
In Ontario, emission tests are required alternate years only on cars after they're 7 years old down to 1988. My Formula had to be tested this year, with less than 6,000 kilometers driven since the last test. A little overkill there I think...
[This message has been edited by David Hambleton (edited 04-02-2015).]
Lol! Well, sometimes I'm easily baffled. For example, I couldn't seem to get your HERE link to be functional in my reply. And I would have preferred to post a PDF copy of the service manual page rather than a picture, but haven't found out how.
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I had a hilarious problem on my Saab 9000 - radiator hose sprung a leak and hosed down the distributor which resulted in a loss of spark. A mountain of fuel got dumped into the exhaust unburned and kersploded in the catalytic converter. That car had a straight-through Dynomax muffler on a 3" exhaust, and with nothing to get in the way I blew the cat's entire substrate out onto the road behind me. It was dark, and the flaming mess just littered two lanes of the highway. Fortunately nobody was around and it was funny and not scary. 
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