elanman

I am trying to understand what exactly the oil filler/separator is on a 944.This is specific to the NA but the same part appear s to be used on the turbo
The big diameter black moulding appears to suggest a cyclone for separating out the oil entrained in the blow by gas. The returned blow by (the top exit in the centre of the moulding to which the rubber hose attaches) is fed in pre the throttle, the separated oil drops back into the block via the drain hole at the bottom of the large diameter black moulding (this is the one where that requires the new O rings when reinstalling) The top port (the other O ring)that enters the engine supplies the blow by gas into the cyclone (separator)
What I am trying to understand is what else is in the black moulding? There must be a check valve to stop the cyclone pressuring directly from the block. It would only let oil separated into the block when the engine is keyed off. Is this facilitated by an umbrella valve? Also is there a PCV valve at the top of the moulding to control the flow rate into the cyclone from the engine chamber at the top of the engine

John_AZ

Not specific to the 944 but the concept is the same.

I have not heard of a check valve inside.

http://www.pelicanparts.com/techarti..._Separator.htm

If you have oil in the throttle body, the AOS seals are bad/leaking. Oil will also show on the drivers side below the AOS black body.

John

elanman

Great thanks for confirmation and link to Pelican but I would stil like to know whether there are any valves or control venturior chokes in it.

I am getting oil in the intake but O rings seals were replaced and separator flush out .Still oil after overun and then high revs with load

There should be a valve to stop crancase pressurising and it only opens when keyed off

John_AZ

The design is very basic.
http://www.callasrennsport.com/porsc...eparators-101/

You might have a vacuum check valve problem.

John

elanman

Vacuum check valve ?? Where might that be ?

I can't see how this AOS separator can work without a control valve of some kind.Also looking at other posts there appears to be nothing in it (it is not a cyclone?)

Really would be a great help to confirm that this is working or not, before I start tearing the head of a looking at valve stem seals etc

V2Rocket

Here is an extremely detailed engineering-quality drawing of the AOS function.

Oil vapor (green) comes in the top port and sinks down to the bottom. The central tube has a vacuum drawing on it from the J-boot of the intake system. As the vapor settles down some of the less-dense vapor (yellow/green) gets sucked out into the intake. The heavier vapors (olive) condense as they fall down and drain back into the pan.

John_AZ

WOW !

Nice Spencer!

Even vapor!

John

MAGK944

Is that Brad Penn (the green oil) that's good stuff

That is exactly how it works. FYI when you go dry sump on these engines that AOS is removed and the vapors are normally directed to some sort of catch can instead of directly into the intake. They are still drawn off by vacuum but caught in the can instead of being fed as fumes into the intake.

V2Rocket

Yup. Catch can design is pretty much the same as the AOS, just with no "outlet"...

elanman

Thank you for the engineering drawing may be we should be using 3D modelling (CATIA prefered!)

So it is a cyclone! No check valves in the moulding I guess you (someone) has cut one of these apart
,any upstream in the J tube or downstrean in the block? I can't see how this can work if it is a PCV system it must have a control of some kind! The sizing of the apertures must work as chokes to limit flows(Clever as Porsche didn't have CFD when developing this cyclone)

Looks like it is the valve stem seals in my case(or even worse the rings) !

V2Rocket

IIRC there is a restrictor inside the tube that the vacuum is drawn on.

elanman

Now we are getting somewhere!

Controlled choke !

John_AZ

I think you need the AOS delete ....

John_AZ

and more

http://forums.pelicanparts.com/porsc...ap-o-ring.html