Water Hose. Porsche 986 / 987 Boxster 1997-08

Water Hose.
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

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