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Oil Separators & Vent lines
By OE Match
- 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
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
This AOS oil / air separator by OE Match is listed for Porsche 996 and 997.1 3.6L applications, including the Carrera variants detailed in the fitment section.
Fits
- Porsche 996 (911) 1997–2005
- Porsche 996 Carrera 2 3.6L 09/2001–2005
- Porsche 996 Carrera 4 3.6L 09/2001–2005
- Porsche 996 Carrera 4S 3.6L 09/2001–2005
- Porsche 996 Turbo 2000–05
- Porsche 997 (911) Mk1 2005–08
- Porsche 997 Mk1 Carrera 2 3.6L 2005–08
- Porsche 997 Mk1 Carrera 4 3.6L 2005–08
Check fitment for your specific vehicle (model, year, engine) before ordering.
Diagram Ref No 1.
What This Product Does
The air/oil separator forms part of the engine crankcase ventilation system. It removes suspended oil droplets from blow-by gases before the gases are directed towards the intake. Separated oil can return to the crankcase, helping to limit the amount of liquid oil reaching the intake tract.
Functions
- Separates oil mist from crankcase gases.
- Supports controlled crankcase ventilation.
- Returns separated oil towards the engine crankcase.
- Routes treated blow-by gases into the intake system.
- Helps prevent excessive oil contamination within the intake.
Technical Details
- Part number: 99610702652.
- Related earlier reference: 99610702651.
- Component type: air/oil separator for the crankcase ventilation system.
- Diagram application: Porsche 996 Carrera 2, Carrera 4 and Carrera 4S with M96.03 engine from 2002.
- Diagram application: Porsche 997.1 3.6L Coupé and Cabriolet with M96.05 engine, 2005–08.
Symptoms of Fault
- Heavy white or blue exhaust smoke, particularly after starting or idling.
- Increased engine oil consumption.
- Rough, unstable or hunting idle.
- Whistling or honking sounds from the crankcase ventilation system.
- An oil filler cap that is unusually difficult to remove because of excessive vacuum.
- Oil deposits around the throttle body or intake pipework.
- Misfire or mixture-related faults where oil or unmetered air enters the intake.
- Cracked, brittle or leaking associated breather lines.
Why Replacement Matters
A deteriorated separator may allow liquid oil to pass into the intake or create abnormal crankcase vacuum. Replacing the faulty component helps restore the intended ventilation path and may address smoke, oil consumption or idle problems caused by the AOS. The adjoining vent lines, seals and connections should also be inspected because age-hardened pipes can crack when disturbed. Occasional brief smoke from a flat-six engine does not by itself confirm separator failure, so oil level, breather integrity and other possible causes should be checked before replacement.
FAQs
- Does exhaust smoke always indicate AOS failure?
No. Oil overfilling and other engine faults can produce similar symptoms, so diagnosis is recommended. - Can a faulty separator cause misfires?
Yes. Oil entering the intake or a vacuum leak within the breather system may affect combustion and foul spark plugs. - What else should be inspected?
Check the oil level and examine the vent lines, connections, seals and intake pipework for oil residue, cracks or leaks. - Is this the same separator used on a Boxster?
AOS problems are also discussed in relation to Boxster models, but this part is listed for the Porsche 996 and 997.1 applications shown above.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610702652
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.
