Coolant Hoses - Centre Section

O-ring – 46.7 x 3.53 – used in various applications within the car's cooling system.

Fits:
Porsche 987 Boxster 2005-12
Porsche 987 Cayman 2006-12

Porsche 981 Boxster 2012-16 
Porsche 981 Boxster Spyder 2016 
Porsche 981 Cayman 2014-16 
Porsche 981 Cayman GT4 2016 

Porsche 718 (982) Boxster 2017>> 
Porsche 718 (982) Boxster Spyder 2019>>
Porsche 718 (982) Cayman 2017>>
Porsche 718 (982) Cayman GT4 2019>>

Porsche 996 GT3 / RS 1999-05
Porsche 996 Turbo / GT2 2001-05

Porsche 997 Carrera 2005-12
Porsche 997 Turbo / GT2 RS 2007-13
Porsche 997 GT3 / RS 2007-11

Porsche 991 Carrera 2012-19
Porsche 991 Turbo / GT2 RS 2014-20
Porsche 991 GT3 / RS 2014-21

Related reference numbers
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99610680103

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O-ring – 46.7 x 3.53 – used in various applications within the car's cooling system.

Fits:
Porsche 987 Boxster 2005-12
Porsche 987 Cayman 2006-12

Porsche 981 Boxster 2012-16 
Porsche 981 Boxster Spyder 2016 
Porsche 981 Cayman 2014-16 
Porsche 981 Cayman GT4 2016 

Porsche 718 (982) Boxster 2017>> 
Porsche 718 (982) Boxster Spyder 2019>>
Porsche 718 (982) Cayman 2017>>
Porsche 718 (982) Cayman GT4 2019>>

Porsche 996 GT3 / RS 1999-05
Porsche 996 Turbo / GT2 2001-05

Porsche 997 Carrera 2005-12
Porsche 997 Turbo / GT2 RS 2007-13
Porsche 997 GT3 / RS 2007-11

Porsche 991 Carrera 2012-19
Porsche 991 Turbo / GT2 RS 2014-20
Porsche 991 GT3 / RS 2014-21

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610680103

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O ring seal water pipe, 39.3 x 3.53 mm
This original Porsche sealing ring is used in the engine cooling system, helping seal the coolant pipe connection and prevent coolant leaks.
Sold individually, 

Fits:
Porsche 987.1 Boxster 2005 - 2008
Porsche 987.2 Boxster 2009 - 2012
Porsche 987C.1 Cayman 2005 - 2008
Porsche 987C.2 Cayman 2009 - 2012

Diagram ref no 39

This O-ring is used on selected Porsche 987 Boxster and Cayman cooling system pipework.

What This Part Does / Functions
•  Seals the water pipe / coolant pipe connection
•  Helps prevent coolant leaks
•  Maintains cooling system pressure
•  Supports correct coolant flow through the engine and radiator circuit
•  Helps prevent air entering the cooling system
•  Replaces a hardened, flattened, cut or leaking original O-ring
•  Provides correct OE Porsche size, material and fitment
•  Supports correct reassembly after coolant pipe or hose service.

Why Replace This Part?
Coolant O-rings are exposed to heat cycles, coolant pressure, vibration and age-related rubber deterioration. Over time, the seal can harden, flatten, crack or lose elasticity. A worn O-ring may allow coolant seepage from the pipe connection, leading to coolant loss, pressure loss or low coolant warnings. Replacing it with a Genuine Porsche OE water pipe O-ring helps restore the correct seal and supports reliable cooling system operation.

Common Symptoms of a Failed Water Pipe O-Ring
•  Coolant leak around the water pipe connection
•  Dried coolant residue near the pipe joint
•  Low coolant warning
•  Coolant smell from the engine bay
•  Cooling system pressure loss
•  Air entering the cooling system
•  O-ring found flattened, cut or hardened during inspection
•  Coolant seepage after previous pipe or hose work.

When to Replace This Part
•  Whenever the water pipe or coolant pipe is removed
•  During coolant hose or pipe replacement
•  If coolant is leaking from the pipe connection
•  If the O-ring is hardened, flattened, cracked or damaged
•  During cooling system overhaul or repair
•  When replacing related coolant pipes, hoses or housings
•  After separating the water pipe connection
•  Whenever Porsche workshop procedure recommends replacing the seal after removal.

Where It Fits on the Car
This O-ring fits in the engine cooling system water pipe / coolant pipe connection. It is commonly shown in Porsche cooling diagrams in the feed and return water hose / coolant hose centre section area. Correct installation is important. The sealing surface should be clean, and the O-ring should be fitted without twisting, pinching or damage.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610680107

The product you are viewing cross references to these numbers

O ring seal water pipe, 39.3 x 3.53 mm
This OE Match O-ring seal is a replacement coolant pipe sealing ring used within the engine cooling system. It is designed to match the original-style fitment and function, helping restore a secure seal at the water pipe joint.
Sold individually

Fits:
Porsche 987.1 Boxster 2005 - 2008
Porsche 987.2 Boxster 2009 - 2012
Porsche 987C.1 Cayman 2005 - 2008
Porsche 987C.2 Cayman 2009 - 2012

Diagram ref no 39

The O-ring seals the water pipe connection to prevent coolant seepage or pressure loss. A correctly fitted seal helps maintain cooling system integrity, stable coolant circulation, and reliable engine temperature control.

Functions
•  Replaces the water pipe O-ring seal
•  Seals the coolant / water pipe connection
•  Helps prevent coolant leaks and seepage
•  Supports correct cooling system pressure
•  Suitable for water pipe, thermostat, radiator hose, or coolant system service
•  Replaces hardened, flattened, cracked, swollen, or damaged
•  O-rings OE Match replacement for Porsche 987 cooling system repair

Why Replace This Part?
Coolant O-rings can harden, flatten, crack, swell, or lose sealing ability due to heat cycles, coolant exposure, pressure, age, and previous service work. A worn or damaged O-ring may cause coolant leaks, low coolant warnings, pressure loss, overheating, or residue around the pipe connection. Replacing the seal helps restore proper coolant system sealing.

When to Replace This Part
•  Coolant is leaking around the water pipe connection
•  The water pipe or related hose has been removed
•  The original O-ring is hard, flattened, cracked, swollen, or damaged
•  Cooling system pressure loss is being investigated
•  Low coolant warnings are present
•  Preventative replacement is required during cooling system service
•  The vehicle is undergoing Porsche 987 Boxster or Cayman cooling system repair

Where it fits on the car
This O-ring fits at the water pipe connection within the engine cooling system on Porsche 987 Boxster and Cayman models. Exact position can vary depending on engine type and coolant pipe layout.

Related reference numbers
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99610680107

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Water Coolant Distributor Tube. SUPPLY



Fits:
Porsche 987 Boxster MKI & MKII 2005>>
Porsche 987C Cayman MKI & MKII 2005>>
Porsche 997 Carrera 3.6L / 3.8L 2005-12
Porsche 997 Turbo MKI & MKII 2007>>
Porsche 997 GT3 2007-11

This product supersedes Porsche's old part numbers:
- 99710615203

Click 'Zoom in' for large parts diagram.
Diagram ref no 8.

Related reference numbers
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99710675204

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Water Coolant Distributor Tube. SUPPLY



Fits:
Porsche 987 Boxster MKI & MKII 2005>>
Porsche 987C Cayman MKI & MKII 2005>>
Porsche 997 Carrera 3.6L / 3.8L 2005-12
Porsche 997 Turbo MKI & MKII 2007>>
Porsche 997 GT3 2007-11

This product supersedes Porsche's old part numbers:
- 99710615203

Click 'Zoom in' for large parts diagram.
Diagram ref no 8.

Related reference numbers
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99710675204

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Water pipe. RETURN LINE.



Fits:
Porsche 987 Boxster MKI 2005-08
Porsche 987 Boxster MKII 2009-12
Porsche 987C Cayman MKI 2006-08
Porsche 987C Cayman MKII 2009-12

Porsche 997 Carrera 3.6L / 3.8L MKI 2005-08 COUPE / CABRIO
Porsche 997 Carrera 3.6L / 3.8L MKII 2009-12 COUPE / CABRIO / TARGA
Porsche 997 TURBO / TURBO S / GT2 / GT2 RS 2007>>
Porsche 997 GT3 2007-11

Click 'Zoom in' for large parts diagram.
Diagram ref no 2

Related reference numbers
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99710672003

The product you are viewing cross references to these numbers

Water pipe. RETURN LINE.



Fits:
Porsche 987 Boxster MKI 2005-08
Porsche 987 Boxster MKII 2009-12
Porsche 987C Cayman MKI 2006-08
Porsche 987C Cayman MKII 2009-12

Porsche 997 Carrera 3.6L / 3.8L MKI 2005-08 COUPE / CABRIO
Porsche 997 Carrera 3.6L / 3.8L MKII 2009-12 COUPE / CABRIO / TARGA
Porsche 997 TURBO / TURBO S / GT2 / GT2 RS 2007>>
Porsche 997 GT3 2007-11

Click 'Zoom in' for large parts diagram.
Diagram ref no 2

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99710672003

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Water Pipe, Supply Tunnel. 

The Porsche Water Pipe, Supply Tunnel 98710665104 is a genuine Porsche replacement coolant supply pipe for selected 987 Boxster and Cayman models.

Fits:

• Porsche Boxster 987 2.7L 2005-08/08
• Porsche Boxster 987 MKII 2.9L 2009-12
• Porsche Cayman 2.7L 987C 2006-08
• Porsche Cayman 2.9L 987C MKII 2009-12  

Diagram Ref No 15

Running longitudinally through the vehicle's centre tunnel, this pipe forms part of the main liquid-cooling circuit connecting the rear-mounted engine with the front-mounted radiator system.

The Porsche 987 cooling system relies on long supply and return pipes to transport coolant between the engine and radiators. A secure, unrestricted supply pipe is therefore essential for maintaining coolant circulation, system pressure and stable engine temperature.

As a Genuine Porsche component, 98710665104 provides the factory-specified routing, dimensions and connection points for the applicable vehicle.

What This Product Does:
The centre-tunnel supply pipe carries coolant through the vehicle as part of the pressurised engine cooling system.

Its main functions include:

• Carrying coolant through the centre tunnel
• Connecting the rear engine cooling circuit with the front radiator circuit
• Maintaining continuous coolant circulation
• Helping maintain correct cooling-system pressure
• Supporting stable engine operating temperature
• Helping transfer heat away from the engine
• Maintaining the original Porsche coolant routing
• Providing a leak-free connection when correctly installed and sealed

The supply pipe works together with the corresponding return tunnel pipe to create the main coolant path between the engine and front radiators.

Symptoms Of Wear Or Failure:
Coolant pipes can deteriorate through age, corrosion, vibration, road contamination and repeated heat cycles.

Common symptoms include:

• Visible coolant leakage beneath the vehicle
• Coolant dripping from the centre tunnel area
• Pink, white or crusty coolant deposits
• Falling coolant level
• Frequent need to top up the expansion tank
• Low coolant warning
• Sweet coolant smell
• Corrosion or pitting on the pipe
• Damaged or distorted pipe sections
• Leakage around pipe connections or seals
• Cooling-system pressure loss
• Fluctuating engine temperature
• Higher-than-normal coolant temperature
• Steam or coolant vapour
• Engine overheating

Small leaks may only appear when the engine is fully warm and the cooling system has reached operating pressure.

Why Replacement Matters:
A leaking coolant supply pipe can reduce both coolant quantity and system pressure.

As coolant is lost, air may enter the system and circulation can become less effective.

Continued operation with a damaged pipe can contribute to:

• Loss of coolant
• Reduced cooling efficiency
• Cooling-system pressure loss
• Air pockets within the system
• Localised hot spots
• Engine overheating
• Reduced heater performance
• Coolant warning messages
• Roadside breakdown
• Serious engine damage if overheating becomes severe

Replacing a deteriorated tunnel pipe restores the integrity of the coolant circuit and helps maintain reliable temperature control.

Related reference numbers
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98710665104

The product you are viewing cross references to these numbers

Water tube return.



Fits:
Porsche 987.1 Boxster 2.7L 2005-08 Tiptronic Transmission
Porsche 987.1 Boxster 3.2L / 3.4L 2005-08 
Porsche 987.2 Boxster 2.9L 2009-12 PDK Transmission
Porsche 987.2 Boxster 3.4L 2005-08
Porsche 987C.1 Cayman 2.7L 2006-08 Tiptronic Transmission
Porsche 987C.1 Cayman 3.4L 200-08
Porsche 987C.2 Cayman 2.9L 2009-12 PDK Transmission
Porsche 987C.2 Cayman 3.4L 2009-12

Click 'Zoom in' for large parts diagram.
Diagram ref no 16

Related reference numbers
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98710665204

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