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Coolant Hoses - Engine Bay
Genuine Porsche 98710650107 (replaces 98710650106) coolant hose for 987 Boxster and Cayman models. OEM-grade multi-layer hose with factory-moulded routing and Porsche-specific connectors for perfect fit, leak-free sealing and reliable cooling performance.
Fits:
Porsche 987.1 Boxster 2.7L / 3.2L / 3.4L 2005 - 2008
Porsche 987C.1 Cayman 2.7L / 3.4L 2006 - 2008
Diagram ref no 1
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
98710650107
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 Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08

Fits:
Porsche 987 Boxster / Boxster S 2005-08 (I480 / I481)
Porsche 987c Cayman / Cayman S 2006-08 (I480)
Porsche 986 All manual 1997-2004 (I480) / (I481)
* I480 - 6-speed manual transmission
* I481 - 5th-speed manual transmission
This product supersedes Porsche's old part numbers:
- 996 106 222 15
Click "Zoom in" to see the diagram.
Diagram ref no 10.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610622217
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 Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
Renew the coolant overflow connection on your Porsche Boxster with this genuine OEM overflow hose. Designed for the Boxster 1997-2008, this main fill/overflow hose links the cooling system to the expansion reservoir, ensuring proper coolant expansion, return flow and system pressure stability.
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 Boxster 987 2.7L 2005 -08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
Diagram Ref No 29
What This Product Does:
- This hose functions as the connection between the cooling system (likely radiator or coolant header) and the overflow/expansion reservoir. When coolant expands under heat or pressure, surplus fluid flows into the reservoir; conversely when the system cools, fluid returns.
- Ensures that cooling system overflow is safely directed, that the reservoir receives the fluid, and that the cooling circuit maintains correct pressure, volume and recirculation.
- Proper operation helps avoid coolant loss, maintain correct cooling system levels, and helps prevent boil-over or overheating due to un-controlled coolant expansion.
Symptoms Of Wear Or When To Replace:
- Coolant leakage around the reservoir, hose clamps, or along the path of the overflow hose — e.g., dripping coolant, crusty residue near joints.
- Overheating or low coolant, where the expansion reservoir remains dry, suggesting the hose isn’t delivering returning fluid or has collapsed.
- Burst, cracked or hardened hose— rubber hoses degrade with heat/age, causing soft spots, bulges, cracks or collapse under pressure.
- Hose slack or loose clamps— if the hose is long out of service it might sag, the ends may be brittle, or clamps may be corroded leading to poor seal.
- If the vehicle is running very hot or the coolant level drops unexpectedly, and checks show the overflow system not functioning properly.
- On older Boxsters many cooling-system hoses are aged and replacement is preventive maintenance.
Why Replacement Matters:
- Maintains cooling system integrity: A faulty overflow hose can lead to coolant loss, pressure escape or improper reservoir return—affecting system performance and engine cooling.
- Prevents overheating or coolant loss: Since the hose handles expansion flows, failure can result in overflow at wrong points or low reservoir levels, which may lead to engine overheating or damage.
- Reliability and longevity: Rubber coolant hoses degrade over time due to heat, vibration and pressure cycles — replacing them restores system reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610626703
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

Fits:
Porsche 986 Boxster Tiptronic M249
Click 'Zoom in' to see the diagram.
Diagram ref no 10.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610622216
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 Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08

Fits:
Porsche 986 Boxster Tiptronic M249
Click 'Zoom in' to see the diagram.
Diagram ref no 10.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610622216
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 Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
Coolant Hoses – Engine Bay | Reliable Cooling for Peak Porsche Performance
Coolant hoses in the engine bay are critical components that circulate coolant between the radiator, water pump, and engine block — maintaining consistent operating temperatures and preventing overheating. These hoses carry coolant through high-pressure, high-temperature zones within the engine bay, ensuring your Porsche performs at its best, even under demanding conditions.
At Design911, we stock a wide range of genuine and manufacturer-quality engine bay coolant hoses for Porsche models including 911, Boxster, Cayman. Each hose is designed to fit perfectly, resist extreme temperatures, and deliver long-lasting performance — matching the quality, precision and reliability.
What Do Engine Bay Coolant Hoses Do?
Coolant hoses form part of your Porsche’s closed-loop
cooling system. Their job is to:
- Circulate
coolant between the engine, radiator, and water pump.
- Maintain
engine temperature for optimal performance and emissions.
- Support
consistent coolant pressure during operation.
- Prevent engine overheating and protect internal components from heat damage.
In high-performance engines, such as those found in Porsche vehicles, properly functioning hoses are essential for ensuring precise temperature control and long-term mechanical integrity.
Why Do Engine Bay Coolant Hoses Fail?
Over time, coolant hoses endure constant exposure to heat,
vibration, and pressure, which can cause wear and eventual failure. Common
causes include:
- Rubber
deterioration from heat cycling and coolant chemicals.
- Cracking
or hardening due to age and environmental factors.
- Swelling
or soft spots from internal coolant corrosion.
- Leaks
at connections caused by weakened hose ends or clamps.
- Abrasion or rubbing against other engine components.
Symptoms of failure include coolant leaks, overheating, fluctuating temperature readings, or a noticeable smell of coolant in the engine bay.
Why Replace Faulty Coolant Hoses?
A damaged or leaking hose can cause rapid coolant loss and severe engine overheating. Replacing worn hoses ensures your Porsche’s cooling system functions reliably and efficiently.
Benefits of replacement include:
- Restored coolant circulation and temperature control.
- Prevention of leaks, overheating, and potential engine damage.
- Improved reliability and performance under all driving conditions.
- Manufacturer-quality construction and perfect fitment.
All hoses in this range are built using reinforced, high-grade rubber compounds designed to withstand extreme heat, pressure, and vibration — ensuring lasting durability and peace of mind.