Finally getting ready to receive final components to put together the aftermarket Air Oil Separator, should be ready in the next few days, the initial run is quite small (16 pz) and perhaps we can get a few more done in the future, 5 are already spoken for and one is for my 99 as I will replace the non-professional made prototype with one of these. so there will be 10 of these available if anyone is interested.
the prototype is been running great for over 5500 miles so far and it eliminated AOS issues for good, it is keeping the intake and throttle body oil free.
Here is a basic description of the functions and benefits of it
Case Study on 986 AOS / PCV (Air Oil Separator / Positive Crankcase Ventilation)
The AOS/PCV system does several tasks (or is supposed to)
A) Recirculates/evacuates oil vapors/fumes produced by blowby, piston bottom compression and oil breakdown from the crankcase to the throttle body (intake) to be burned and avoiding such gases from reaching the environment.
B) Avoids high pressure build up (positive crankcase pressure) preventing pressure from blowing seals off (rear main seal, spark plug seals and most importantly Intermediate Shaft Bearing Seal (IMS).
C) Close (or restricts) flow under low idle conditions to avoid un-metered air/gasses from entering the throttle body and avoid a CEL (check engine light), rough idle and a lean operating condition.
D) Open (or de-restrict) flow under non-idle conditions to accomplish the burning and recirculation of gasses as described in A) above. the engine management system adjusts for this condition to avoid a CEL (check engine light)
E) Separate fumes, oil vapor, blow by and oil decomposition gasses into oil and air
returning oil into the crankcase and letting only air into the throttle body (intake).
When AOS/PCV system fails it causes the following problems:
A) Does not open when is supposed to open and excessive crankcase pressure produces oil leaks thru the weakest exit points of the engine like spark plug seals, main seals including IMS, once a seal is broken an oil leak will be produced, in the case of the IMS the factory bearing seal can fail, engine oil washes the bearing and the bearing fails, engine can self destroy due to de-syncronization of mechanical components.
B) Opens when is supposed to close, allows un-metered air and fumes into throttle body (intake) producing a lean condition in engine producing a CEL (check engine light) in severe cases causing pre-ignition and ping destroying pistons and rings, it also allows lots of fumes and oil particles to be ingested into the throttle body (intake) and causing oil to be burned into the cylinders (smoke clouds), hydrolock (destruction of engine by mechanical components like rods to bend or brake by forces trying to compress oil instead of fuel/air gasses inside combustion chambers) foul spark plugs and possible damaging catalytic converters and Oxigen sensors.
OEM AOS DESCRIPTION AND PROBLEMS:
OEM AOS system is an empty plastic reservoir with a non repleaceble (buit in) pcv valve on top to provide the closing and opening functions under possitive/negative pressure (vacuum/pressure) conditions, it is supposed to separate air from oil by centrifugal forces produced by the conical spyral shape of the container and returning the separated oil back into the engine crankcase by a drain fitting about 1/4" in diameter. there is a plastic fin or gate that is supposed to prevent oil from going back into the two main AOS intakes, once the return of oil into the small drain compartment gets overwhelmed that portion of AOS container becomes full of oil ready to be ingested by the engine. The PCV on top (valve that opens and closes) is a flexible diaphragm
that functions as long as is not ruptured or hardened, oil and specially acidic decomposed oil affects this diaphragm so as long as the AOS is new and not too much oil has touched this diaphragm it functions as designed. when the diaphragm starts to fail it will cease to function as designed loosing it's flexibility or by developing cracks and leaks.
Note: some new OEM AOS are known to fail out of the box
Additional problems with OEM AOS:
The system is connected to the engine to 4 points:
1) A flexible bellow rubber hose (intake point #1)
2) An accordion plastic hose to the top of drivers side engine head (Left Drivers Side version, this is intake point #2)
3) Oil return fitting (Drain) a plastic fitting at the bottom/side of the AOS with o ring seal.
4) An plastic tube (J tube) from the top of the AOS/PCV to the throttle body.
Accordion/plastic hoses and their ends fatigue and crack with engine heat leaking oil and air, these ends are pressure clips that rely on thin rubber o-rings for sealing, these ends are very prone to fail as engine ages.
The brittle plastic tubes/hoses are ridged (accordion) and retain lots of oil instead of letting it drain to the engine crankcase.
OEM AOS is a complete unit and it needs to be replaced as a whole when fails, it is a tedius and expensive task to be replaced.
Stelan AOS system:
The Stelan AOS system is comprised of the following components:
Separator Can
Manifold
Rubber hoses to replace all accordion plastic hoses
Drivers side engine head fitting to replace plastic fitting
Clamps to replace all plastic pressure clips and o-rings
VW 1.8 Turbo PCV valve to replace OEM integrated PCV
Advantages
Drivers side head fitting
This fitting replaces the OEM plastic fitting that has a spring loaded blow off valve, this plastic fitting cracks as other plastic components, the new fitting allows the use of larger diameter rubber hose with better flow with better oil/air separation properties and more secure hose/clamp sealing.
Separator Can
The Stelan Air/Oil separator it is a metallic maintenance-free reservoir, filled with stainless steel media, thousands of metallic swirls and spyrals that condense fumes (condensation is the change from gas to liquid) separating air from oil returning oil to the crankcase via the largest block opening preventing the system from ever filling up with liquid oil, the bottom of the container has a conical shape to facilitate a positive drain of fresh liquid oil that will decay and decompose less by being airated (foamed) as the AOS does and allowing fresh clean air to the the PCV valve, the PCV valve sees less liquid oil thus increasing it's longevity and actually preventing liquid oil from being ingested by the engine, this can is a part that will never need replacing.
PCV VALVE
The PCV valve is a component taken from a VW/AUDI 1.8 Turbo engine, it is superior than the OEM valve due to the following facts:
Affordable to replace ($6.00-$35.00 depending on where you purchase it) versus OEM $125.00 - $250.00.
Easy to replace, it takes 2-5 minutes to replace versus OEM 1-3 hours, you can even have an additional one in the glove box and change it on the side of the road with only a screwdriver.
Longevity, the 1.8T valve is made of a stronger material internally as it is designed to sudden pressure changes natural of a tubocharged engine.
This part will need to be replaced if ever needed.
Hoses and Clamps
Rubber hoses that will last decades that are significantly larger in ID (inside diameter) for better flow, smooth inside for positive oil return to the crankcase versus the accordion ridges in OEM plastic tubes that accumulate oil ready to be ingested into the engine, the PCV-to-throttle body rubber hose and clamp fit over throttle body fitting to eliminate pressure clip for positive sealing.
These hoses are
1) Hose from drivers side engine head to manifold.
2) Hose from PCV valve to throttle body
3) hose from AOS manifold to engine block (silicon)
OIL RETURN PLUG
this is a mall rubber hose and screw to block the tiny OEM engine block oil return, this small engine block opening is not longer used and it is blocked with the Stelan AOS system.
it is a part that will never need replacing.
MANIFOLD
The Stelan AOS system manifold connects rubber hose from drivers side vent and main intake/drain and separator, it mounts where OEM resided and aids in the draining/cooling and distribution of oil/air, it is a part that will never need replacing.
It includes everything you need to replace OEM with instructions (no tools included).
Also would like to thank all of the forum members that participated in the research / ideas / tech info, etc.
Linear Mode
