KNS

Perhaps enough time and mileage haven't accumulated yet but I hear of few AOS failures (maybe a couple..?) compared to the 996. On my 188,000 mile BMW daily I"m still on the original CCV (AOS by another name). Maybe Porsche figured it out with the 997.

WindyCityC2S

I believe the part number on the 997.1 AOS is a 996 part. SO I doubt there was any big improvement there. Not sure about 997.2s.

WindyCityC2S

I believe I am mistaken...looks like a 997 part.

LexVan

If you want a more robust part for the 997 buy the Motorsport version.

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KNS

The AOS design (and its placement) changed in late 2005/2006 so I'm wondering if it is better design as well.

alexb76

If you don't track, it doesn't matter. If you track, it's perfectly fine on stree tires, but if you are really fast, have track tires, it'd then may not be sufficient. For street use it's way more than adecuate.

997_rich

I track ~5 times a year on street tires and I cooked my AOS ~4 years into ownership at ~100k miles.

I had an '05 AOS in the car originally and the replacement AOS part was exactly the same (I installed myself).

If it fails again I'll go for the motorsports version (which is twice the cost).

alexb76

You should have checked if the 06+ part# is different, I believe it is, as they changed it along with IMS upgrade. I haven't had any problem apart from ONCE when I over-filled with oil.

997_rich

I pulled my old parts fiche from '05 and there was never any update that I can see for the 997 (with M96 engine) or 997 (with m97 engine). Same part numbers today. Perhaps there was an older part on the 996(with M96 engine) but it doesn't look like it was ever on the 997.

Here are the parts we're talking about:

M97
http://www.pelicanparts.com/cgi-bin/...g_description=

M96
http://www.pelicanparts.com/cgi-bin/...g_description=

motorsports version
http://www.pelicanparts.com/cgi-bin/...07-926-00-M100

NOT this one.. this is another air oil separator that is also on the engine in a different place but it is not the one that commonly fails.
http://www.pelicanparts.com/cgi-bin/...107-080-54-OEM

997_rich

By the way here are some pics of the failed part. I agree 100% that oil overfill is going to contribute to this failure. You can see the rubber bellows are browned and finally cracked due to oil foam/mist attacking the elastomeric.

I had a warning that the failure was coming in the form of a loud whistle that sounded like a slipping belt. It was the air passing though the cracked bellows like the reed on a clarinet.

Macster

Be sure the Motorsports version is compatible with your car's MY. I'm under the impression is it not a bolt on for 997 MY's, but some have adapted it.

BTW, 100K miles out of an AOS is pretty good. My 2002 Boxster is on its 3rd replacement AOS and they have all lasted anywhere from 80K to 100K miles, oh with street use only. No track time.

Based on my experience I have to say the AOS is a wear item, like brakes or plugs, and one just has to accept that after while the thing will just wear out and have to be replaced.

I do not know about any overfilling the engine with oil affecting AOS life. I'd not overfill the engine with oil regardless but I do try to run the oil level up near the max level to ensure the engine has a good supply of oil at all times.

IslandS52

My AOS went on my 06 at 71k miles.