Breather Hose. Porsche 996 / 997.1 1998-08

Breather Hose.
Restore the engine ventilation routing on your Porsche 911 (996 / 997 series) with this genuine breather hose. This hose is located at the top of the oil cooler and connects the breather or ventilation circuit, ensuring proper air/oil vapour flow and system integrity.

Fits:

• 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 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

Diagram Ref No 30

What This Product Does:

• The breather hose is part of the engine’s ventilation or crankcase/air-oil management system. In this case, it's described as being located at the top of the oil-cooler, which may mean it connects the crankcase ventilation or engine breather output back into the intake or another system.
• Its main function: to provide a path for gases (blow-by, vapor, pressure) from the engine or oil-cooler area back into the intake system or safe discharge path.
• The hose must withstand engine heat, pressure/vacuum cycles, vibrations, and exposure to oil or vapour, and provide a leak-free connection.
• Proper functioning helps maintain correct crankcase pressure, prevents undue pressure build-up or vacuum, helps control emissions, keeps the oil cooler circuit operating correctly, and ensures the engine’s ventilation system does not allow unintended air or oil vapour to escape or enter in the wrong way.

Symptoms Of Wear Or Failure:

• Oil vapour or smell around the engine compartment, especially near the oil cooler area or hose routing, indicating leakage of crankcase gases.
  
• Visible cracks, splits, brittleness, or hose collapse — old hoses can harden, crack or collapse internally causing blockage or leakage.
  
• Unusual engine behaviour: e.g., increased oil consumption, engine smoking slightly, or unusual intake/vacuum behaviour — if ventilation is compromised.
  
• Check engine or emission warnings: A compromised breather hose may lead to induction of unmetered air or vapours, affecting engine management.
  
• Oil cooler area contamination: Because the hose is described as located at the top of the oil cooler, if oil or vapour-contaminated deposits are visible there, the hose may be failing.
  
  

Why Replacement Matters:

• Maintains correct engine ventilation: A good breather hose ensures proper crankcase/ventilation flow, and prevents pressure build-up or vacuum conditions that can lead to leaks or part failures (seals, gaskets).
  
• Protects the oil-cooler circuit and engine components: Because this hose is located at the oil-cooler top, replacing it helps ensure the oil cooler and associated hoses remain uncontaminated by vapour or oil mist escaping via degraded hoses.
  
• Improves reliability: Since these hoses are subject to heat, pressure and ageing, replacing them proactively avoids sudden failure, which could leave the car stranded or cause engine issues.

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

99610623053

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