1999Porsche911

We are talkiing 996 CAT's here, not other cars. Are you trying to tell us that you have replaced 50 996 CAT's? I find that hard to believe since they are an emission warranty item that would be replaced free by the dealer.

Alan C.

When I had both cats replaced on my 02 the dealer indicated that he had replaced the cats on 2 other cars in the not too distant past. That's 6 cats.

It may be that there was a bad supply of substrate for the cats. If one considers that the metal substrate is rolled to 0.0015", thinner than your hair, then a 10,000 lb. master coil would yield a lot of cats. Fecralloy and Apha-4 used to be common substrates for cats and both are difficult to make at best. I've been away from those products for a while so I'm not sure if they are still the prime candidates.

Either of those alloys will withstand 1000C, 1832F, with no problems. To get beyond that temp the cat would have to be subjected to an overly rich condition. The typical failure mode for a metal cat would be small shards of metal separating from the monolith and exiting with the exhaust. However, if you have two cats in tandem the downstream cat might get plugged by an upstream failure. That is what you don't want to happen as you would get increased back pressure on the engine. A good reason not to ignore a CEL.

99firehawk

all but maybe 2-3 fell under 8yr/80k and were replaced by dealer
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1999Porsche911

So, what you really mean is that most of the other's were damaged by something that would not be covered by warranty or replaced by choice and not neccessity? Otherwise, any failure of a CAT not due to modifications would be fully covered since all but the earliest 996's under the mileage limit are still covered by Porsche.

99firehawk

No the ones that wernt under warrenty had over 80k miles on them, 80k is the limit on emissions warrenty.

8 yrs or 80k miles emissions warrenty on cats and dme

Adrian

Why don't you check Firehawk's public profile and see what he does and where he works.
Ciao,
Adrian.

pwr2lbs

Im in with firehawk. Definetly replace more cats then lamda probes. And the dealer doesnt care, they dont pay for it, Porsche does.