Wyovino: The current AOS have a oil return to the sump which is located at the back of the engine, it bolts directly to this hole. If you relocate it you will most likely need to drill a new oil return hole somewhere in the lower part of the engine and pull a hose there. If you decide that this system is good for you then just replace and keep it in place. It can be done with the engine in the car (what I've read online), but a little tricky. I personally find this system a bad compromise and will replace it with a catch can solution which can be easily serviced.

 

FWIW,, the same vintage BMW's have the same issue and more with the AOS system.
Theirs is just as goofy as the Porsche one and is almost as expensive.
Theirs didn't have the hot water heating and used to freeze up in the winter, unless you
bought the 300 dollar piece of insulation that covered the AOS lines..
The lines also age badly and fail dumping oil all over the place.

 

Nick - Please start a new thread when you install this on your car. If your idea works, there will be others looking to follow your lead.

This thread has become a bit diluted from its original intent - starting a new one, for a new idea only makes sense.

Sorry - I missed the link to your other thread. It still think it makes sense to split off from that one with your AOS specific plan.

 

Sure thing. I will create the thread after I have a system that I feel is solid and fully functional.

 

The "motorsports" units are bulletproof, however I've always wondered myself if you could use a Mann/Hummel Provent instead. Granted it's big, bulky, and mounting it high enough in the engine bay in some installations won't be feasible, but I'm going to try putting one on my aircooled 911 in the spring:

https://oe-products.mann-hummel.com/...ProVent_en.pdf

 

Hi Charles, do you still sell the Motorsport AOS adapter for the 1st gen engines ?

 

Yes. We are going to be releasing a how to for making new hoses when using our motorsports aos adapter on a 5 chain engine.

 

I want to try that.

 

If the problem is too high a vacuum gradually destroying a diaphragm inside the AOS unit, would the easiest remedy be an inline check valve that when vacuum reaches a certain level then the valve closes and protects the diaphragm? That would seem to allow the factory AOS to last indefinitely.

The valve could be small and easy to mount where the AOS vacuum line connects to the throttle body, and quickly removed if needed for a visual smog check. It could be calibrated to be open most of the time to allow normal operation of the AOS, and only close under high vacuum conditions.

 

996.2: the function that you describe for the check valve is the exact function that the diaphragm is doing, closing when a certain vacuum is reached. From pictures I've seen I suspect acid oil is the culprit 'eating away' at the diaphragm. The original unit have no good way of protecting the diaphragm from the oils.

 

Correct!

 

Part of the problem is the oil return from the AOS ends in the sump and sits close or under the oil level. With a failing AOS oil gets sucked like
a straw via this return line back into the AOS and partly into the intake.

Part of the return line is integrated in the engine block, running through a small ribbon along the sump side wall. One could drill a hole through the sump wall at a height well above the oil level and ending in this block integrated oil return line to provide a sort of ’venting’ line for the oil return line from the AOS.

If high vacuum gets applied the AOS the oil will not get sucked up. The return line will draw air from the channel made. This could give some safety for the engine as the AOS will not directly be flooded with oil.

 

Can one of the experts on these things explain why running a vacuum pump or tandem pump (on the head) wouldn't produce a more consistent vacuum source without any connection to the actual intake?

 

Running an engine driven vacuum pump is less efficient and has a simple problem that would need to addressed.

Since the internal combustion engine is it's self an air pump, using it's self to evacuate/vacuum the crankcase is the most efficient way.

If running an engine driven vacuum pump, the exhaust from the vacuum pump would contain oil/vapor mist and would need to be collected/disposed of in some fashion.

This is actually what is being done with DRY-sump multistage aftermarket systems. The engine driven oil pump has several "stages", some are used to create a vacuum on the crankcase, and the exhaust is just expelled in the oil tank and recirculated.

I have an idea for correcting the misgivings of the factory AOS system. That will maintain the factory design but take care of all the misgivings and still function as designed.. Stay tuned !!!! I will make a new thread when done....

 

Interesting!

if you can place a link here so I don’t miss it.