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Last October, my friend suffered a catastrophic failure of her driver-side catalytic converter. This did serious damage to my friend's GT4 -- burned wires, melted fuel line, blown cat, melted suspension bushing, etc. Ended up costing her nearly $12K to get everything fixed, and required the engine to be pulled to do it. Here are a few pics:
And John Gaydos posted this to FB last week:
How common are these failures? And, any idea what causes/caused them? I'm guessing some kind of thermal shock caused the whole O2 sensor bung to just tear out of the cat shell. She says this is becoming more common, but I haven't seen anything on RL about it yet.
I crawled under my car and inspected both cats, and they seem to be okay. However, I would definitely like to avoid this happening to my car. I'm adding inspecting the cats to my normal maintenance routine. Perhaps the only pre-emptive way to prevent this might be aftermarket headers. Hey, John, group purchase?
Wow, first I've seen it. Usually if the catalytic substrate breaks apart, it's easy to hear it rattling around. Nothing preceded the failure?
Her failure was the first I've heard of it as well. She had no warning, except for when the check-engine light came on. She was on track at the time, and there's a chance she may have noticed the car was a bit louder before the check-engine light came on, but she's not sure since there's lots of noise on the track.
From the reports I received, the cat substrates were perfectly fine. It was the shell that failed. And, since the substrates were fine, Porsche said the federal emissions warranty didn't apply and they refused to cover anything.
Her cats were actually less than two years old at the time of failure. She bought the car from a dealer, who had to replace the complete aftermarket exhaust the previous owner installed before the car would pass MD inspection.
I've heard of aftermarket cats failing(Cargraphic/others) on high flow headers and being sucked into the 981 GT4 engines causing big problems which is why I've always told friends to not buy any aftermarket catted headers for the 981 GT4's.
I've heard of aftermarket cats failing(Cargraphic/others) on high flow headers and being sucked into the 981 GT4 engines causing big problems which is why I've always told friends to not buy any aftermarket catted headers for the 981 GT4's.
I've heard of problems with aftermarket cats, too. This is the first I've heard of problems with genuine Porsche cats.
I've been contacted privately/offline by a couple of people, who have experience this problem or witnessed it. This issue seems more widespread than I thought.
I had one of my headers crack with fairly consistent track use at about 15k miles. The shop I use to prep my car, happens to support a large number of GT4 and clubsports. They say almost every GT4 with consistent track use will have the drivers side manifold crack.
Last edited by Five12Free; 01-13-2023 at 11:53 PM.
This issue was mentioned on today's PCA National PodCast, with the owner of the first report present.
After looking at the photographs at the top of the thread, that is not a failure of the weld, but of the cat housing base material at the toe of the weld. I wonder what the specific material/alloy of the cat shell is and the material/alloy of the weld filler material. Perhaps hydrogen embrittlement of the base material due to inadequate preheat of the base metal before depositing the weld metal?
I had a weld fail on one my stock headers at 15k miles, good amount of track use (20+). It failed on the track, sounded like a tractor very obvious it was leaking. Same deal, melted a ton of stuff (vaccum lines, wiring harness etc). Car was at Porsche for 3 months, all covered under CPO. I'm sure it would of cost minimum $10k. If your going to track a lot I recommend replacing the headers if your out of warranty.
I had one of my headers crack with fairly consistent track use at about 15k miles. The shop I use to prep my car, happens to support a large number of GT4 and clubsports. They say almost every GT4 with consistent track use will have the drivers side manifold crack.
I had my car at my favorite Indy shop for pre-season inspection and service. Took a good look at the O2 sensor bungs and saw no evidence of cracking/failure. But we saw longitudinal crack along the flange seam weld of the Bank 2 (left) header/cat housing. Appears to be consistent with the report from Five12Free. I had the crack weld repaired. We had to cut the heat shield to follow the crack to the end, then weld it back together. I'm at 24k miles with about 10 track days/season. Thankfully, caught it before any damage was done. Before & after photos attached.
01-11-2023, 07:25 PM
Catalytic Converter failures?
