Fluid Hoses & Pipes

Breather Line.

The Porsche Breather Line 9GT301047A is a genuine Porsche replacement ventilation line used within the PDK transmission and clutch breather system on selected Porsche 911 GT3 applications.

Fits:

• Porsche 992.1 GT3 4.0L / 992 S/T 4.0L 2021-24
• Porsche 992.1 GT3 RS 4.0L 2022-24  

Diagram Ref No 34

The line forms part of the gearbox ventilation arrangement, providing a controlled route for pressure equalisation as the transmission and clutch assembly heat up and cool down during operation.

Porsche catalogues the part for the 7-speed PDK transmission code CBG.91, where it is fitted as a single breather line within the transmission assembly.

Manufactured as a genuine Porsche component, it provides the correct dimensions, connections and routing for the original installation.

What This Product Does:
During operation, transmission components and lubricants become hot.

As temperature increases, the air and vapour inside the transmission housing expand. A properly functioning breather system allows these pressure changes to be managed without excessive internal pressure building inside the gearbox.

The breather line helps:

• Vent the PDK transmission and clutch housing correctly
• Allow internal pressure to equalise as temperatures change
• Route gearbox vapour through the intended ventilation path
• Prevent excessive pressure building inside the transmission
• Support correct operation of gearbox seals and gaskets
• Reduce the likelihood of oil being forced past sealing surfaces
• Maintain the original Porsche gearbox ventilation arrangement

Although it does not directly control gear selection or clutch engagement, it supports the environment in which these components operate.

Symptoms Of Wear Or Failure:
Breather lines can deteriorate through heat, vibration, age or physical damage.

Possible symptoms include:

• Visible cracking or splitting
• Hardened or brittle hose material
• Kinked or crushed tubing
• Loose connections
• Line becoming detached
• Oil mist around the breather connection
• Transmission oil residue around the gearbox
• Dampness around adjacent fittings
• Unusual oil seepage from gearbox seals
• Repeated transmission oil leaks with no obvious seal failure
• Contamination or debris blocking the breather line
• Damaged retaining clips or supports

Because this is a passive ventilation component, a failed line may not immediately trigger a dashboard warning.

Why Replacement Matters:
A damaged, disconnected or blocked breather line can interfere with the transmission's ability to manage internal pressure.

Continued operation with a defective breather may contribute to:

• Increased gearbox oil leakage
• Additional stress on transmission seals
• Oil contamination around surrounding components
• Loss of transmission lubricant
• Dirt or moisture entering the breather system
• Premature deterioration of associated seals
• Increased maintenance requirements

Replacing a failed line restores the intended ventilation route and helps maintain the transmission's designed operating environment.

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

9GT301047A

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