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Coolant Bottles / Expansion Tanks
By OE Match
- 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 Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- 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
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MK1 GT2 2007-09
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
This coolant bleed valve cap restore proper sealing and pressure control at the coolant bleed valve on Porsche 996, 997 , Boxster and Cayman models. Its mounts to the coolant distribution housing and provides a secure, leak-free closure for the system's air-bleed point. The cap is supplied complete with 8 mounting screws and the required sealing ring, ensuring a precise fit and reliable installation.
Fits:
Porsche 996 1998 - 2005
Porsche 997.1 2005 - 2008
Porsche 986 Boxster 1997 - 2004
Porsche 987.1 Boxster 2005 - 2008
Porsche 987.1C Cayman 2005 - 2008
Diagram ref no: 3, 4, 11, 12
This product supersedes Porsche's old part numbers:
- 99610634700
- 99610634701
Manufactured to match Porsche’s original materials and dimensions, this cap resists heat, coolant exposure, and pressure fluctuations. It maintains correct system sealing during coolant expansion and contraction cycles, helping prevent air pockets, coolant leaks, or pressure loss that can compromise engine cooling performance.
A worn or damaged bleed valve cap can cause:
• Coolant leaks at the bleed housing
• Loss of system pressure, leading to overheating
• Difficulty bleeding the cooling system properly
• Air pockets that reduce coolant circulation and cooling efficiency
Replacing the cap ensures proper cooling-system sealing and prevents costly overheating issues.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610634702
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 Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- 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
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MK1 GT2 2007-09
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
This coolant expansion tank cap is a direct replacement for Porsche 996 (1998–2005) and also fits Boxster (986/987), Cayman, and 997 models, upgrading earlier versions with improved sealing and pressure control.
Fits:
Porsche 996 1998 - 2005
Porsche 997.1 2005 - 2008
Porsche 986 Boxster 1997 - 2004
Porsche 987.1 Boxster 2005 - 2008
Porsche 987C.1 Cayman 2005 - 2008
Diagram ref no 5
This cap serves as the pressure seal for the coolant expansion tank, keeping the cooling system at the correct pressure. It regulates venting to the overflow reservoir, preventing blowback, leaks, and overpressure while helping avoid coolant loss, boiling, and overheating.
It replaces earlier versions: 99610644700, 99610644701, 99610644702, 99610644703
Why replacement matters:
• An old or worn cap may fail to hold pressure, causing coolant to boil, vaporize, or overflow
• A bad cap can allow air to enter the cooling system, leading to overheating, hot spots, or poor cooling performance
• A leaking or weak cap can lead to gradual coolant loss, requiring refills and risking engine damage
Installing an OE-Match version restores proper pressure control, reliable sealing, and helps maintain engine temperature stability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610644704
The product you are viewing cross references to these numbers
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
Fits:
Porsche 987 Boxster 2.7L Boxster S 3.4L 2007-08 Chassis no F988U7 02382>> and F988U7 22205>>
Porsche 987 Boxster 2.9L / Boxster S 3.4L 2009-12
Porsche 987C Cayman 2.7L / Cayman S 3.4L 2006-08 Chassis no F988U7 52756>> and F988U7 72799>>
Porsche 987C Cayman 2.9L / Cayman S 3.4L 2009-12
Click 'Zoom in' for large parts diagram.
Diagram ref no 1
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
98710604703
The product you are viewing cross references to these numbers
OEMatch Coolant Bottles and Expansion Tanks — Durability, Sealing, Performance
Coolant bottles and expansion tanks store excess coolant and manage pressure as the engine heats and cools, maintaining system volume on Porsche models. Many owners search for genuine or OEM coolant bottles and expansion tanks; these are direct-fit alternatives designed to match the original form, fit and function. Replacing a degraded tank reduces the risk of coolant loss and overheating.
- Replacement plastic reservoirs for standard cooling systems
- Pressurised expansion tanks with integrated sensor mounting
- Pressure caps and remote overflow tanks
OEM (Original Equipment Manufacturer) parts are made by the same company that produced your Porsche's original coolant bottles and expansion tanks. OE (Original Equipment) refers to parts matching original specifications for the coolant bottles and expansion tanks and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM coolant bottles and expansion tanks engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models. OEMatch supplies a wide range of Porsche parts, from gaskets to suspension hardware, engine items and interior trim. The company has catalogued over 4,000 part numbers and more than 8,700 OE cross-references, and continues to expand its Porsche-focused range.
- Restored coolant capacity and stable system pressure
- Reduced risk of leaks and overheating
- Improved reliability and easier level monitoring
- Plastic fatigue or cracking from thermal cycling
- Leaks at seams, hose connections or caps
- Faulty pressure caps or contamination within the cooling system
A compromised expansion tank can cause rapid coolant loss, pressure instability and overheating, which in turn may lead to engine damage. Timely replacement restores system integrity, helps maintain correct pressure and coolant level, and supports consistent engine operating temperatures on Porsche vehicles.
- Direct replacement options made to original-spec dimensions and tolerances
- Compatible mounting points and sensor interfaces where applicable
- Material choices intended to resist heat, pressure and vibration
Support & Advice
These items affect safety-critical systems. Installation should be carried out by a qualified technician following model-specific procedures and torque settings. Use calibrated tools and new fasteners where specified.
