Coolant Top Hose, LEFT. Porsche 987 Boxster & Cayman / 997 › 99710662504

Coolant top hose Return, LEFT
The Genuine Porsche return hose is an original equipment cooling system component. This upper left-hand coolant hose forms part of the vehicle's water cooling system, connecting the left-side radiator to the coolant return circuit. It allows coolant to circulate efficiently, helping regulate engine temperature and maintain reliable cooling system operation.

Fits:
Porsche 987.1 Boxster / Boxster S 2005 - 2008
Porsche 987.2 Boxster / Boxster S 2009 - 2012
Porsche 987C.1 Cayman / Cayman S 2006 - 2008
Porsche 987C.2 Cayman / Cayman S 2009 - 2012
Porsche 997.1 Carrera 2 / 2S 2005 - 2008 CABRIO/COUPE 
Porsche 997.2 Carrera 2 / 2S 2009 - 2012 CABRIO/COUPE
Porsche 997 GT3 2007 - 2010

Diagram ref no 10.

This product supersedes Porsche's old part numbers: 99710662503

Manufactured to Porsche's original specifications, this genuine replacement hose provides precise fitment, durability and resistance to coolant pressure and temperature fluctuations.

Ideal for replacing cracked, leaking or deteriorated original hoses during cooling system repairs or preventative maintenance.

What Does This Part Do? – Functions

• Coolant Return: Carries coolant through the left-hand radiator return circuit.
• Temperature Regulation: Supports efficient engine cooling and stable operating temperatures.
• Leak Prevention: Maintains a secure, sealed coolant connection.
• Heat Resistance: Designed to withstand coolant temperatures and operating pressures.
• Original Fitment: Maintains Porsche factory cooling system specifications.

Why Replace This Part?
Over time, coolant hoses can become brittle, cracked or weakened due to constant heat exposure, coolant pressure and ageing. A deteriorated hose may develop leaks, leading to coolant loss, reduced cooling efficiency and potential engine overheating.

Replacing a worn or damaged hose with a genuine Porsche component helps restore reliable coolant circulation, prevent leaks and maintain the original performance of the cooling system.

When to Replace This Part?

• Coolant Leaks: Visible coolant escaping from the hose or its connections.
• Cracked Rubber: Splits, hardening or deterioration of the hose material.
• Swollen Hose: Bulging or deformation caused by ageing or pressure.
• Engine Overheating: Rising temperatures associated with coolant loss.
• Cooling System Repairs: During radiator replacement or coolant system maintenance.

Where Does It Fit on the Car?
Location: Front left-hand side – upper radiator coolant return connection.

The coolant top hose is fitted to the upper section of the left-side radiator cooling circuit, connecting the radiator to the associated coolant return pipework. It allows coolant to flow through the return circuit as part of the engine's liquid cooling system.

Fitting Position: Left-hand side (LH), upper coolant return hose.
Parts Diagram Reference: No. 10

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

99710662504

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