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Oil Separators & Vent lines
By OE Match
.jpg?width=197 "AOS Oil / air separator & hose kit Porsche Boxster 986 2003>> 99610702602 - 99610702601, 99610702600, 99610702602, 996-107-026-01, 98710714502, 98710724601, 99610717550, 98710714602")
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
One of the most common failures in the Boxster or 996 is the Air/Oil Separator, also referred to as the AOS.
Fits:
Porsche Boxster 986 2003 - 2004
Porsche Boxster 987.1 2005 - 2008
Porsche Cayman 987C.1 2005 - 2008
Diagram Ref No 1, 4, 5, 10
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.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
OILSEPARATOR.986S.2.OEM
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
AOS Oil / Air Separator
Maintain the performance and reliability of your Porsche
Boxster 986 with this OE Match Oil / Air Separator (AOS). A
critical component of the M96 engine crankcase ventilation system, the Air Oil
Separator helps separate oil vapour from crankcase gases before they are
returned to the engine intake system.
Fits:
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
Diagram ref no 1
During normal engine operation, pressure builds inside the crankcase and oil vapour becomes suspended within the circulating gases. The AOS removes this oil mist, allowing the oil to return to the engine while directing cleaned gases back into the intake system for emissions control and efficient combustion.
The Air Oil Separator is a well-known service item on Porsche M96 engines. As the internal diaphragm ages and deteriorates, the separator can lose its ability to regulate crankcase vacuum correctly, leading to a variety of drivability and engine performance issues.
Manufactured to OE Match specifications, this replacement unit provides the correct fitment and performance needed to restore proper crankcase ventilation and engine operation.
What Does the Oil / Air Separator Do?
The AOS forms part of the Positive Crankcase Ventilation (PCV) system and performs several important functions.
Its primary roles include:
- Separating oil from crankcase vapours
- Returning oil to the engine
- Regulating crankcase vacuum
- Reducing oil consumption
- Supporting emissions control
- Maintaining engine efficiency
- Preventing excessive oil contamination of the intake system
Without a functioning AOS, excess oil can be drawn into the intake system and combustion chambers.
Why Do Air Oil Separators Fail?
The Air Oil Separator contains an internal diaphragm and valve assembly that is constantly exposed to heat, vacuum and engine oil vapours.
Common causes of failure include:
- Diaphragm deterioration
- Age-related wear
- Heat cycling
- Oil contamination
- Internal valve failure
- High engine mileage
- Crankcase pressure fluctuations
- Long-term exposure to engine vapours
Over time, the separator loses its ability to regulate crankcase pressure correctly.
Symptoms of a Failing AOS
A failing Air Oil Separator often produces noticeable warning signs.
Common symptoms include:
- Excessive white smoke from the exhaust
- Increased oil consumption
- Rough idle
- Vacuum leaks
- Whistling or squealing noises
- Check engine warning lights
- Oil residue in the intake system
- Excessive crankcase vacuum
- Difficulty removing the oil filler cap while the engine is running
These symptoms are common indicators that the separator requires replacement.
When Should the AOS Be Replaced?
Replacement is recommended whenever symptoms of failure appear.
The AOS should also be considered during:
- High-mileage maintenance
- Engine rebuilds Intake system servicing
- Preventative maintenance programmes
- Crankcase ventilation system repairs
Many Porsche specialists regard the Air Oil Separator as a preventative maintenance item on ageing M96 engines.
Why Replacement Matters
A failing AOS can affect engine performance, emissions and long-term reliability.
Benefits of replacement include:
- Improved idle quality
- Reduced exhaust smoke
- Lower oil consumption
- Correct crankcase pressure regulation
- Improved engine efficiency
- Reduced intake contamination
- Enhanced reliability
- Restoration of factory engine operation
Replacing a failing separator early can help prevent additional maintenance costs and drivability concerns.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610702602
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
Fits:
Porsche 986 Boxster - 1997 to 2004
Porsche 996 C2 / C4 3.4ltr - 1998 to 2001
Click 'Zoom in' for large parts diagram.
Diagram ref no 9
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99951263000
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
Fits:
Porsche 996 1998-02 3.4L
Porsche Boxster 986
Click 'Zoom in' for large parts diagram.
Diagram Ref No 10.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610723752
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 996 TURBO 2000-05
Fits:
Porsche 986 Boxster - 1997 to 2004
Porsche 996 - 1997 to 2005
Porsche 996 turbo - 2000 to 2005
- Guaranteed fitment
- Helps prevent harmful fuel vapors from escaping into the atmosphere
- Failing Vapor Canister Purge Valve can create a vacuum leak and cause rough idle.
- Helps restore proper air to fuel ratio for optimal gas mileage.
Click 'Zoom in' for large parts diagram.
Diagram ref no 9
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99660521301
The product you are viewing cross references to these numbers
OEMatch Oil Separators & Vent lines — Durability, Sealing, Performance
The oil separator and vent line system manages crankcase ventilation on Porsche engines by separating oil vapour from blow-by gases and returning cleaner air to the intake. Properly functioning separators and breather hoses reduce oil contamination and help preserve throttle response, idle quality and long-term engine cleanliness. OEMatch supplies replacements and related hoses prepared for Porsche applications to support routine maintenance and rebuilds.
Available Types- Oil separators (breather housings)
- Breather hoses and vent lines
- Seals, grommets and connection fittings
OE (Original Equipment) refers to parts matching original specifications for the oil separators & vent lines and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM oil separators & vent lines engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models.
The oil separator and vent system controls crankcase pressure, removes oil vapour from circulating gases and keeps intake air free of oil droplets.
When functioning correctly the system prevents oil entering the intake tract, reduces smoke and limits carbon build-up on inlet valves and ports. OEMatch also maintains a catalogue of more than 4,000 individual part numbers and over 8,700 OE cross-references to aid correct selection for Porsche applications.
- Restores clean airflow and stable crankcase pressure
- Reduces oil leaks, blue smoke and carbon accumulation
- Supports consistent idle and throttle response
- Clogged or degraded internal membranes inside separators
- Cracked, hardened or collapsed breather hoses due to heat and age
- Worn seals, grommets or connection points causing leaks
- Vacuum leaks affecting idle and throttle response
- Sludge or condensation build-up inside vent lines
Replacing a worn or damaged separator or vent line restores correct crankcase breathing and helps avoid progressive engine issues such as oil contamination, valve deposits and inconsistent running. Fitted components specified for Porsche engines help preserve emissions performance and reduce the risk of oil reaching the intake tract. Select parts that match the original connections and materials for reliable long-term operation.
Advantages- Direct-fit replacements engineered to match original dimensions and tolerances
- Components manufactured in heat- and oil-resistant materials for longevity
- Catalogue cross-references and part numbers to support correct selection for Porsche models
Installation should be carried out by a qualified technician following model-specific procedures and torque settings. Use calibrated tools and new fasteners where specified. If you are unsure about hidden sensors or routing, seek professional installation to ensure correct sealing and operation.
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