Breather / Vent Hose. Porsche 986 / 987 Boxster 1997-06  ›  99610625703

The Genuine Porsche Breather / Vent Hose is a replacement hose used within the engine cooling and coolant expansion system on selected Porsche Boxster models.

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 2005-06
• Porsche Boxster 987 S 3.2/3.4L 2005-06

As the engine heats and cools, coolant expands and contracts while small amounts of trapped air may move through the system. The vent hose helps manage this movement between cooling-system components so that unwanted air pockets do not interfere with normal coolant flow.

With age, repeated heat cycles and prolonged exposure to coolant, the original hose can harden, crack, split or begin leaking around its connections. Replacing a deteriorated hose helps restore a sealed cooling circuit and reduces the risk of coolant loss or air entering the system.

What This Product Does:
The coolant breather hose forms part of the engine's liquid-cooling system.

It is designed to:

• Provide a vent path within the cooling circuit.
• Help move displaced air through the cooling system.
• Assist with coolant circulation between connected components.
• Help prevent unwanted air pockets forming within the cooling system.
• Maintain a sealed coolant circuit.
• Carry coolant where required during expansion and contraction.
• Support correct operation of the expansion-tank and cooling-system arrangement.
• Replace a cracked, leaking or hardened original hose.
• Help maintain correct coolant level and system pressure.

• Visible coolant leakage.
• Dampness around the hose or its connections.
• Dried coolant residue around fittings.
• Gradual reduction in coolant level.
• Coolant smell around the engine compartment.
• Hose becoming hard or brittle.
• Visible cracking.
• Splits in the hose.
• Swelling or deformation.
• Leakage when the cooling system becomes hot and pressurised.
• Air repeatedly entering the cooling system.
• Coolant-level warning appearing.
• Engine temperature becoming less stable.
• Coolant collecting around nearby components.
• Steam or coolant vapour from the engine area in severe cases.

Similar symptoms can also be caused by the expansion tank, cap, water pump, radiator hoses or other cooling-system components, so the actual source of the leak should be confirmed.

Why Replacement Matters:
The cooling system needs to remain sealed to maintain the correct coolant volume, pressure and circulation.

A leaking vent hose can allow coolant to escape and may permit air to enter the system as the engine cools.

Replacing a damaged hose helps restore:

• A sealed cooling circuit.
• Correct coolant retention.
• Proper cooling-system venting.
• Stable engine temperature.
• Reliable coolant circulation.
• Reduced risk of air pockets.
• Long-term cooling-system reliability.