Originally Posted by Mfletch

Your car has a sweet looking rear end....perhaps someone got fresh with it. http://www.youtube.com/watch?v=HvuY1nO27Go







I'm sorry...I couldn't resist.

Originally Posted by Michael Gibney

Thanks Ivan.

I can do most tech work -- but am unbearably slow! Was a pro tech on Alfa's and Fiats about 30 years ago -- that WAS interesting.

Just did a search on AOS and saw the following -- seems to cover the subject well...

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The Engine oil air separator directly affects the engine crankcase atmosphere because basically all Porsches from 1980 on including the current 986-987-996-997-Caymen & Cayenne engines are all positive crankcase type systems meaning the engine crankcase has vacuum supplied from the intake manifold to collect and burn the residual combustion by-products or blow-by in the crankcase by running it through the engine again, basically to lower the overall vehicle emissions.

On most occasions, when the oil separator fails, intake vacuum in the engine crankcase rises to an unusually or abnormal rate and more likely than not ends up drawing engine oil into the intake system usually fouling spark plugs and even possibly causing damage to the oxygen sensors (O2), catalytic convertors and even possibly various other sensitive fuel injection components.

Interestingly enough, the only way to test the oil separator is to periodically test the engine crankcase vacuum with a water filled Monometer AKA an ultrasensitive vacuum gauge. On BMW’s and Porsche’s, the engine crankcase vacuum is normally around 4-7” (Inches) of water. When these oil separators fail the crankcase vacuum can rise to 9-12” and even higher depending on the extent of the failure.

When the oil separator is starting to fail on Boxsters (986-987), generally you will start to see a substantial amount of smoke from the exhaust tailpipe. When the oil separator finally fails, the engine exhaust smoke can reach dangerous proportions that almost look like it was manufactured from an anti-mosquito smoke machine. Unusually enough, on the 999-997’s, when the oil separator fails, it hardly ever creates any exhaust tailpipe smoke, almost being like a silent killer or costly surprise.

On another note, it has been known on rare occasions, that when an oil separator fails that it is possible to cause or create a slightly rich running condition that might turn on the check engine light or CEL.

The only way to know what is/was happening is to check the fuel trim numbers on the OBD-II “Freeze Frame” data and crankcase vacuum to see exactly what’s going on, otherwise your just guessing.

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So tomorrow I will see what the vacuum is like and will get back to you -- will see if I can get a photo.

Changing the AOS will be an interesting job -- strange that I look forward to the job -- when the "proper" outcome would be for there to be no problem.

Thanks