Opposer

Hi guys.

I've heard the hypothesis that catalytic converters are prone to decay on old cars (mine is 987 mk2 2.9 2009), which can cause bore scoring because of engine inhaling ceramic 'crumbs' from cats when changing gears. My russian pals persuaded me to buy decatted headers (not from them, just an ebay), so that I can avoid this.

How realistic is this theory? Should I decat 10-year old Cayman to avoid bore scoring?
my car has 30k miles on odometer.

Marine Blue

On the direct injection 987’s I’ve heard the bore scoring is caused by faulty leaky injectors which dilute the oil when the car is turned off. The cylinders don’t have proper lubrication on startup and scoring occurs.

As far as I know the best solution to this is having an oil analysis done with every oil change to monitor the fuel levels in the oil and if you see an increase have the injectors checked.

Denny Swift

Huh?

How could the engine inhale anything from the downstream cat? Maybe if you connected a powerful shop vac to the heads and banged on the cats with a mallet to shake some stuff loose you could get some crumbs to go upstream😏 Plus if the cats were not working properly, you’d get a dash light and an error code. Sure cats can wear out, but they are not going to send “crumb” upstream to the engine. And the engine would probably start misfiring and running poorly if the cats failed. Oh, and I just saw that you said the car has 30k miles. No way in hell could the cats be worn out. Maybe with 130k...

As far as the injectors scoring the cylinders and leading to gas entering the oil... I think you’d get serious blow-by, by that time, and you’d be engulfed in a cloud of blue smoke if the scoring ever got bad enough to where the gas was getting into the oil. I’d expect you to also get serious misfires and engine stumbles long before the cylinders were scored. And again, no chance at 30k miles.

Opposer

Mine is 2.9, it's non-DFI 9A1.

badabing

Never heard of this

It's fairly easy to drop the mufflers and have a peek inside the cats (may need a borescope).

I have a run a number exhaust configurations on my 987.2CS including fabspeed catless race headers with mini cats and stock exhaust.

Nice sound.

Bought them used right here in the classifieds.

okie981

Bogus theory.

deilenberger

But entertaining..

okie981

The Russians strike again. I like a good conspiracy theory.

Boiler Inspector

I do recall a thread on Planet 9, about 5 or 6 years ago, where a 987.1 owner experienced a blown motor due to failed cats. It seems like in his case he was running aftermarket 200 cell cats, and the cat material was sucked back into the combustion chamber. IIRC he also had metal and oil in the intake. It was very bizarre.

okie981

Internet folklore makes for stories like the front page of the National Enquirer in the 1980’s. I’d like to see Jake Raby’s post-mortem analysis of that engine and the actual failure mode determined.

shus2006croc

Wrong forum.

You should post this in Politics and Controversy Forum.

Thats where all the bogus theories reside.

Boiler Inspector

Post #19 on this thread: https://www.planet-9.com/threads/my-...-killed.89288/

Seems failed AOS was the root cause; failed Eurosport headers caused some damage too.

Denny Swift

rileyracing1

This is a witch hunt - Fake News !!

Boiler Inspector

https://www.planet-9.com/threads/my-...-killed.89288/