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997.2 3.6l AOS (Air Oil / Oil Mist Separator) DIY


How to replace the AOS on 2009+ Carrera (997.2)

I replaced my AOS back in late September this year, and just haven't had a chance until now to compile the DIY.

The car was running great and consuming an average amount of oil according to Porsche guidelines, so this was purely a preventative step. 
Although the car ran great before, it did actually feel a bit better/smoother after the AOS install (particularly at idle and in the lower rev range)

At the time the car had about 72k miles on the clock.
Please excuse all the pollen & dust in the part of the engine bay where the AOS is installed (I don't think it's avoidable :)

I installed the OEM AOS with p/n 9A1 107 040 02 (note this is revision 3 of the part. I do not know what (if anything) has changed since prior versions.

The trickiest part of the job was actually replacing the plenum (air distributor pipe). It's the kind of thing that will always be easier the 2nd time around. Just pay very close attention to how the rubber sleeves are fitted when you first remove the half moon clamps, and you should be fine. This is really key as you do not want this part incorrectly installed and allowing dirty and unmetered air into the system.

Hopefully the pictures below make the steps clear. I borrowed some pics from the web in order to superimpose/highlight key areas.


Step 1: Remove the airbox (there are many posts/DIY's on this step so I won't repeat it here)

Step 2:



Step 3:



Step 4:



Step 5: 
Loosening this harness will provide a lot more flexibility when installing the AOS and also when reinstalling the half moon clamps which connect and hinge from the rear.



Step 6:



Step 7:



Step 8:



Step 9:


For the o-rings I used the following as it was the closest in specs and operating temp to what Porsche recommends and you can actually find the stuff:



Step 10:




Note the left side connector on the AOS is a real pain to get well seated. Also the design I think is flawed in that it will never sit 100% flush. This can also be seen when comparing the 2 ports on the old AOS. You can see that the left side port has some dust above the o-ring, whereas the right side port does not.
I think this really comes down to the design of the part and that the area where it seats has a conical opening.



For reassembly - mount the air distributor/plenum and secure the half moon clamps before replacing the wiring harness conduit mounting screws to ensure more wiggle room back there.

I posted my findings about the change (increase) in the vacuum level after the new AOS install in the thread linked below:

If anyone is doing this DIY or has an opportunity to add their data to the abovementioned mentioned thread on vacuum levels, that would be most appreciated.

It's been over 3 months since the new AOS install and the car still runs beautifully. It is too soon to determine if oil consumption has changed at all, but that was never a concern to start with. 

Today I changed out the air filters and took the opportunity to inspect the throttle body which I'm pleased to say was spotless inside.







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