AOS Oil / air separator with breather pipe kit Porsche 996 3.4L

Crankcase Breather System (Air/Oil Separator)

The crankcase breather system, also known as the air/oil separator (AOS), is a critical engine component that should be replaced every 30,000 miles—or sooner if signs of failure appear.

When the system fails, it can cause:

• Vacuum leaks due to cracked hoses or a damaged air/oil separator
• Oil consumption and fouled spark plugs, as oil is drawn into the intake
• Increased crankcase pressure, which can lead to gasket leaks and other engine issues

Preventative Maintenance

Preventative maintenance is always the best approach. Our comprehensive Crankcase Breather Hose Kit includes all the components you need to replace the system properly. We also recommend performing an engine oil change at the same time to ensure peak performance and longevity.

The AOS is basically a small diaphragm distillery which distills the minute amounts of oil mist in the crankcase, liquifies it and sends it back to the crankcase. The "clean" air is now sent into the air intake (after the throttle body) to be burned off by the engine.

When the AOS starts to fail it cannot separate all of the oil out of the mist and some liquid oil is sent to the air intake.

A few drops of oil is enough to generate the GREAT SMOKE BOMB for which our cars are famous for.

A big smoke bomb once in a while is completely normal, due to the architecture of the flat-6 engine, which may let a drop of oil flow into one of the combustion chambers sporadically.

Fits:
Porsche 996 C2 3.4L 1997-08/01

Porsche 996 C4 3.4L 1997-08/01

Parts included are: 

• 1 x AOS Oil / air separator. Porsche 996 3.4L (ref 99610702355)
• 1 x Oil separator breather hose. Porsche 996 3.4L >>2001 (ref 99610714555)
• 1 x Crankcase breather hose. Porsche Boxster 986 >>2002 / 996 (ref 99610714755)
• 1 x Oil / Air Separator Boot Clamp. Porsche 986 Boxster / 996 >>2001 (ref 99951263000)
• 1 x Oil / Air Separator Boot for Porsche 996 3.4L 1998-02 / Boxster 986 - (ref 99610723752)

Click pictures for large parts diagram.
Diagram Ref No 1, 4 , 5 

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99610702355

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