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Coolant Hoses - Radiator Section
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 Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- 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 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 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 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

It's a common problem with 987 & 997 models that front coolant and cross over pipes behind the front wheels start weeping and become badly corroded, this kit replaces the ones you might need.
Fits:
Porsche 997 Gen 1
Porsche 997 Gen 2
Porsche 987 Boxster Gen 1
Porsche 987 Boxster Gen 2
Porsche 987C Cayman Gen 1
Porsche 987C Cayman Gen 2
Manual & Tiptronic cars.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
WATERPIPEKIT05
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- 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 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 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 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
This OE Match radiator and coolant pipe replacement kit is an all-in-one set of high-quality hoses and pipes engineered to replace the most common radiator and coolant delivery lines on Porsche 987 Boxster / Cayman and 997 Carrera models. Designed to match the factory routing and fitment, the kit includes radiator feed and return hoses, upper intake pipes, bypass lines, and related OE Match connectors required for a thorough cooling system service or overhaul.
Fits:
Porsche 997 Gen 1
Porsche 997 Gen 2
Porsche 987 Boxster Gen 1
Porsche 987 Boxster Gen 2
Porsche 987C Cayman Gen 1
Porsche 987C Cayman Gen 2
Manual & Tiptronic cars.
As engines age and operate under heat cycles and pressure, rubber hoses and coolant pipes can become soft, cracked, swollen, or restricted, leading to leaks, overheating, and reduced cooling performance. This comprehensive OE Match kit provides direct-fit replacements for the critical coolant lines between the radiator cores, coolant pump, thermostat housing, heater core, and engine block. Each component in the kit is manufactured to meet or exceed the original Porsche specification in hose inner diameter, bend geometry, wall thickness, and connection profile so that it installs cleanly into factory brackets and ports without modification. OE Match materials are chosen for long-term resistance to heat, coolant chemical exposure, and mechanical stress, ensuring durable performance throughout the life of the engine. This kit simplifies maintenance and repair by grouping all key radiator and coolant pipe replacements into one convenient solution, reducing parts hunting and ensuring that worn or deteriorated hoses do not compromise the cooling system’s integrity after other components (such as radiators or pumps) are serviced.
What This Kit Does:
The coolant and radiator pipes in this kit work together to:
- Carry coolant flow between the engine, thermostat, heater core, coolant pump, and radiator
- Maintain correct pressure and temperature balance across the cooling system
- Support reliable heat rejection through the radiator cores
- Prevent coolant loss and overheating due to brittle or collapsed hoses
- By matching OE geometry and fitment, these hoses help maintain efficient coolant circulation and stable operating temperatures during normal driving as well as spirited use.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
RADANDPIPEKIT997.OEM
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- 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 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII GT3 / GT3 RS 2010-11
- 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
Right Hand Radiator Feed Pipe
This right-hand radiator feed pipe is designed for Porsche
997 and 987 Boxster / Cayman models. It forms a vital part of the front-mounted
cooling system, carrying coolant from the engine towards the radiator to ensure
efficient heat dissipation.
Fits:
- 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 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 GT3 2007-09
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII GT3 2010-11
- 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
Diagram ref no 10
With Porsche’s mid- and rear-engine layouts, coolant must travel long distances between the engine and front radiators. This makes the condition of coolant pipes critical to maintaining stable engine temperatures and preventing overheating.
What This Radiator Feed Pipe Does
The radiator feed pipe transports coolant from the engine to the front radiator on the right-hand side of the vehicle.
It helps:
• Maintain continuous coolant flow through the cooling
system
• Transfer heat away from the engine to the radiator
• Support stable engine operating temperatures
• Ensure efficient cooling under all driving conditions
• Maintain proper pressure within the cooling circuit
Without a properly functioning feed pipe, coolant flow can be restricted or lost entirely.
Why Radiator Feed Pipes Fail
Over time, coolant pipes are exposed to heat, pressure and environmental conditions that lead to wear and failure.
Common causes include:
Corrosion (on metal sections)
Exposure to moisture and road debris can lead to corrosion over time.
Cracking or splitting
Plastic or rubber sections can become brittle and fail.
Seal and joint deterioration
Connections can weaken, leading to leaks.
Age-related wear
Long-term exposure to heat cycles reduces material strength.
Symptoms of a Failing Radiator Feed Pipe
• Coolant leaks under the vehicle
• Low coolant warning messages
• Engine running hotter than normal
• Visible corrosion or damage on the pipe
• Sweet coolant smell after driving
Replacing a worn or leaking pipe is essential to prevent overheating and engine damage.
Why You May Need to Replace This Pipe
Prevent Engine Overheating
A properly functioning feed pipe ensures reliable coolant circulation.
Fix Coolant Leaks
Replacing damaged pipes restores system pressure and eliminates leaks.
Maintain Cooling System Efficiency
Ensures optimal heat transfer and engine performance.
Essential Preventative Maintenance
Cooling system components should be inspected and replaced as they age.
Direct Fit Replacement
Designed to match original Porsche specifications for correct fitment.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99710662204
The product you are viewing cross references to these numbers
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16

Fits:
Porsche 991.1 Carrera 2012-16
Porsche 981 Boxster 2012-16
Porsche 981SP Boxster Spyder 2016
Porsche 981C Cayman 2014-16
Porsche 981 Cayman GT4 2016
Click 'Zoom in' for large parts diagram.
Diagram ref no 9
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99110662
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 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII GT3 / GT3 RS 2010-11
- 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 / S MKI & MKII 2005>>
Porsche 987C Cayman / S MKI & MKII 2006>>
Porsche 997 GT3 2007-2010
Porsche 997 Carrera 2/2S MKI & MKII 2005>> CABRIO/COUPE
This product supersedes Porsche's old part numbers:
- 99710662603
- 99710662604
Click "Zoom in" to see the diagram.
Diagram ref no 10.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99710662605
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 Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- Porsche Boxster 718 2.0L Manual (300 Bhp) 2017>>
- Porsche Boxster 718 2.0L PDK (300 Bhp) 2017>>
- Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
- Porsche Boxster S 718 2.5L PDK (350 Bhp) 05/2017>>
- Porsche Boxster T 718 2.0L Manual (300 Bhp) 01/2019>>
- Porsche Boxster T 718 2.0L PDK (300 Bhp) 01/2019>>
- Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
- Porsche Boxster GTS 718 4.0L Manual (400 Bhp) 01/2019>>
- Porsche Boxster GTS 718 4.0L PDK (400 Bhp) 01/2019>>
- Porsche Boxster Spyder / Spyder RS 718 4.0L 01/2019>>
- Porsche Boxster 25 Years 718 4.0L Manual (400 Bhp) 01/2020>>
- Porsche Boxster 25 Years 718 4.0L PDK (400 Bhp) 01/2020>>
- 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 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12
- Porsche 997 MKII GT3 / GT3 RS 2010-11
- Porsche 997 MKII Turbo 2010-13
- Porsche 997 MKII GT2 RS 2011-13
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.1 GT3 3.8L (475 Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500 Bhp) 2015-16
- Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Targa 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Speedster 4.0L (510Bhp) 2019
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
- Porsche 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19
- 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
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
- Porsche Cayman 718 2.0L Manual (300 Bhp)
- Porsche Cayman 718 2.0L PDK (300 Bhp)
- Porsche Cayman S 718 2.5L Manual (350 Bhp)
- Porsche Cayman S 718 2.5L PDK (350 Bhp)
- Porsche Cayman T 718 2.0L Manual (300 Bhp)
- Porsche Cayman T 718 2.0L PDK (300 Bhp)
- Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
- Porsche Cayman GTS 718 2.5L PDK (365 Bhp)
- Porsche Cayman GTS 718 4.0L Manual (400 Bhp)
- Porsche Cayman GTS 718 4.0L PDK (400 Bhp)
- Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L
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
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 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
Left Hand Coolant Radiator Breather Hose
High-quality breather hose designed for the left-hand coolant radiator on Porsche 986 Boxster, Boxster S, 996 Carrera 2, Carrera 4, and 996 GT3 models. This component plays a vital role in maintaining proper coolant system ventilation and pressure balance.
The breather hose allows trapped air to escape from the
cooling system, ensuring efficient coolant circulation and preventing airlocks
that can lead to overheating or reduced cooling performance.
Fits:
- 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 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
Diagram ref no 11
Manufactured to OEM specifications, this hose provides precise fitment, durability, and reliable performance. Ideal for maintenance, repair, or replacement of ageing or degraded cooling system components.
Key Features
• Left-hand coolant radiator breather hose
• Designed for Porsche 986 Boxster / Boxster S
• Compatible with Porsche 996 Carrera 2 / Carrera 4 / GT3
• Maintains proper cooling system ventilation
• Helps prevent airlocks in the coolant system
• Supports efficient coolant flow and engine cooling
• OEM-quality fit and durability
• Ideal for replacement or preventative maintenance
Function and Purpose
This breather hose is essential for correct cooling system operation.
It helps to:
• Release trapped air from the coolant system
• Maintain proper pressure balance
• Ensure efficient coolant circulation
• Prevent overheating caused by airlocks
• Support stable engine operating temperatures
Why Replace Coolant Breather Hoses
Cooling system hoses are exposed to heat, pressure, and ageing.
Common issues include:
• Cracking or hardening of hoses
• Coolant leaks
• Reduced cooling efficiency
• Air entering the system
• Risk of overheating
Replacing worn hoses ensures optimal cooling system performance and engine reliability.
Diagram ref no 11
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610613753
The product you are viewing cross references to these numbers
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16

Fits:
Porsche 991 Carrera 2012-16
Porsche 981 Boxster 2012-16
Porsche 981 Boxster Spyder 2016
Porsche 981C Cayman 2014-16
Porsche 981C Cayman GT4 2016
Click 'Zoom in' for large parts diagram.
Diagram ref no 10
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99110662
The product you are viewing cross references to these numbers
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
Ensure proper cooling system operation with the Radiator Coolant Vent Line, LEFT. This OE MATCH vent line is designed to help remove trapped air from the radiator cooling circuit, supporting consistent coolant circulation and stable engine temperature control.
Fits:
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
Diagram Ref No 30
What This Product Does:
- Vents air from the radiator cooling system
- Prevents air pockets that can restrict coolant flow
- Supports consistent coolant circulation
- Helps maintain stable engine operating temperature
- Reduces the risk of overheating
Symptoms Of Wear Or Failure:
- Coolant leaks near the radiator or along the vent line
- Low coolant warning light or frequent coolant top-offs
- Sweet coolant smell from the front of the vehicle
- Coolant residue or staining around fittings or connections
- Cracked, brittle, or leaking vent line material
- Air trapped in the cooling system, causing gurgling sounds
- Fluctuating engine temperature or inconsistent gauge readings
- Overheating, especially after coolant service or refilling
- Steam from under the hood in severe cases
- The radiator coolant vent line plays an important role in allowing trapped air to escape from the cooling system. If the line becomes cracked, brittle, or blocked, air pockets can form in the radiator circuit, reducing coolant flow and cooling efficiency.
- Failure to replace a damaged vent line may lead to coolant leaks, unstable system pressure, fluctuating engine temperatures, and an increased risk of overheating. Even small leaks can gradually reduce coolant levels and compromise performance.
- Replacing the vent line helps ensure proper system bleeding, maintains consistent coolant circulation, and protects the engine from heat-related damage.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99110676502
The product you are viewing cross references to these numbers
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
Fits:
Porsche 991.1 Carrera - 2012 to 2016
Porsche 981 Boxster - 2012 to 2016 incl. Boxster Spyder
Porsche 981C Cayman - 2012 to 2016 incl. Cayman GT4
Diagram ref no 30
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99110676602
The product you are viewing cross references to these numbers
- Porsche Boxster S 986 3.2L 1999-02
- 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
This hose serves as the lower radiator return hose (left side) in the engine cooling system of the Porsche 996 Carrera / Carrera 4 and 986 Boxster S 3.2L. It replaces older hose numbers such as 99610662554 and 99610662557, offering a faithful reproduction of the original hose in terms of shape, diameter, and fitment.
Fits:
Porsche 996 C2 / C4 1998 - 2005
Porsche 986 Boxster S 3.2L 1997 - 2004
Diagram Ref No 9.
The radiator coolant hose circulates engine coolant between the radiator and engine blocks or cooling passages. As a key part of the cooling system, it helps transfer heated fluid away from the engine and into the radiator to be cooled, then back into the engine - maintaining stable operating temperatures and preventing overheating under normal driving conditions. A robust and properly functioning coolant hose ensures efficient heat dissipation and preserves engine performance.
Function:
• Transfers coolant between the radiator and engine cooling system
• Helps maintain optimal engine temperatures
• Reduces the risk of overheating and coolant leaks
• Made from heat- and fluid-resistant materials to endure typical engine bay conditions
Radiator hoses are constantly exposed to engine heat, pressure cycles, and coolant chemicals. Over time, hoses can dry out, crack, soften, or swell, leading to leaks or cooling system failure. A compromised hose can quickly result in engine overheating, potential head gasket damage, and costly repairs. Replacing a worn or aged hose restores secure coolant flow, enhances system integrity, and helps maintain original-style engine temperature management.
Replace this radiator hose if:
• The hose shows cracks, swelling, or brittleness
• Coolant is visible leaking around hose connections or surface
• The hose feels soft or mushy under pressure
• You notice engine overheating or rapid temperature fluctuations
• Routine cooling system maintenance or belt/thermostat replacement
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610662558
The product you are viewing cross references to these numbers
- Porsche Boxster S 986 3.2L 1999-02
- 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 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>

Fits:
Porsche 996 C2 / C4 1998-05 TIPTRONIC
Porsche 996 C4S 1998-05 TIPTRONIC
Porsche 996 GT3 1998-05
Porsche 986 Boxster S 3.2L 1997-04
This product supersedes Porsche's old part numbers:
- 99610666651
- 99610666652
- 99610666655
Click 'Zoom in' for large parts diagram.
Diagram Ref No 9.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610666656
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 986 2.7L 2003-04

Fits:
Porsche 986 Boxster 2.5L / 2.7L 1997-04 (NOT 3.2L S)
This product supersedes Porsche's old part numbers:
- 99610662600
- 99610662601
Click 'Zoom in' for large parts diagram.
Diagram ref no 9.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610662603
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 986 2.7L 2003-04

Fits:
Porsche 986 Boxster 2.5L / 2.7L 1997-04 (NOT 3.2L S) MANUAL
This product supersedes Porsche's old part numbers:
- 99610662101
Click 'Zoom in' for large parts diagram.
Diagram Ref No 8.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610662102
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

Fits:
Porsche 996 C2 / C4 1998-05 MANUAL (NOT C4S)
This product supersedes Porsche's old part numbers:
- 99610662157
Click 'Zoom in' for large parts diagram.
Diagram ref no 8.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610662158
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
OE Match upper-left radiator coolant hose (intake/top hose) designed to replicate the factory hose routing and connections on Tiptronic-equipped 996 and 986 models.
Fits:
Porsche 996 C2 / C4 1998 - 2005 TIPTRONIC
Porsche 986 Boxster 2.5L / 2.7L 1997 - 2004 TIPTRONIC
Porsche 986 Boxster S 3.2L 2000 – 2004
This product supersedes Porsche's old part numbers:
- 99610666555
- 99610666557
Diagram Ref No 8.
This hose transports coolant through the upper (intake) side of the left radiator circuit, supporting efficient heat rejection and stable engine operating temperature.
Function: This hose links the radiator coolant plumbing on the upper-left side and is shaped to maintain correct flow while clearing bodywork, brackets, and neighbouring hoses. Correct fitment is important to prevent restriction, rubbing, and leak paths at the hose ends as the system expands and contracts with temperature.
Cooling hoses are wear items. A weakened upper hose can split or leak under pressure, leading to coolant loss and overheating risk. Replacing with an OE Match hose restores secure sealing and correct routing, helping protect the engine and keep the cooling system operating as intended.
When to replace:
• Visible coolant seepage at hose ends or along the hose body
• Hose feels overly soft, swollen, brittle, or cracked
• Coolant smell/steam from the front of the car
• Cooling system refresh (radiators/thermostat/water pump service)
• Preventatively on higher-mileage 996/986 models
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610666558
The product you are viewing cross references to these numbers
-
water cooling - 3 - for 986 Boxster 1997-04 105-15
-
water cooling - 2 - For 987 Boxster / Boxster S 2005-08 105-10
-
water cooling - 3 - for 987 Boxster / Boxster S 2005-08 105-15
-
radiator centre 986 Boxster S (M96.26/21/22) I249 Tiptronic Transmission 2005-08 105-17
-
Water cooling 2 (Model: A120,A121) 987.2 Boxster/ Boxster 2009-12 105-010
-
Water cooling 3 (Model: A120,A121) 987.2 Boxster / Boxster S 2009-12 105-015
-
Water cooling 981 Boxster / Boxster S 2012-16 105-010
-
Water cooling / Radiator / Fan 982 Boxster / Boxster S 2012-16 105-015
-
Water cooling 981.SP Boxster Spyder 2016 105-010
-
Water cooling / Radiator / Fan 981.SP Boxster Spyder 2016 105-015
Radiator Section Coolant Hoses – Mid & Rear-Engine Porsche Models
Radiator section coolant hoses are essential for managing engine temperature in mid and rear-engine Porsche models. These hoses circulate coolant between the engine and the radiator, ensuring consistent temperature control and preventing overheating under high-performance conditions.
At Design911, we stock a full range of genuine and manufacturer-quality radiator section coolant hoses specifically designed for mid- and rear-engine Porsche models such as the 911, Boxster, and Cayman. Each hose is built to factory specifications for perfect fitment, superior pressure tolerance, and reliable cooling system performance — ensuring your Porsche operates safely and efficiently on road or track.
What Do Radiator Section Coolant Hoses Do?
In Porsche’s mid- and rear-engine designs, coolant must
travel a greater distance between the engine (located at the rear or middle)
and the radiator (at the front). The radiator section hoses form part of
this vital network, helping to:
- Transport
coolant efficiently from the engine to the front radiator.
- Maintain
optimal engine operating temperature for performance and longevity.
- Regulate
coolant flow through the entire system under varying loads.
- Ensure consistent pressure and leak-free circulation.
These hoses are engineered to handle high thermal and mechanical stress, ensuring reliability even in extreme driving conditions.
Why Do Radiator Coolant Hoses Fail?
Due to their exposure to heat, pressure, and constant
coolant flow, radiator section hoses can wear out over time. Common causes of
failure include:
- Material
fatigue from heat cycles and pressure changes.
- Cracks
or splits in aging rubber or plastic connectors.
- Corrosion
or leaks around hose clamps and fittings.
- Swelling
or softening from prolonged coolant exposure.
- Abrasion damage from rubbing against engine or chassis parts.
Symptoms of a failing coolant hose may include coolant leaks under the car, overheating, fluctuating temperature readings, or a low coolant warning light.
Why Replace Faulty Radiator Section Hoses?
A worn or leaking hose can cause coolant loss, overheating, and potential engine damage. Replacing aging hoses is an essential part of preventative maintenance — especially in mid- and rear-engine Porsche models, where efficient cooling is critical.
Benefits of replacement include:
- Restored, leak-free coolant circulation.
- Improved temperature control and system pressure.
- Prevention of costly overheating and engine damage.
- Manufacturer-quality materials for long-term reliability.
All replacement hoses in this range are constructed using reinforced, high-performance rubber compounds and precision-moulded fittings, ensuring durability, flexibility, and perfect compatibility with Porsche cooling systems.