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Porsche > 991 (911) MK2 2016-2019 > 991.2 Speedster 4.0L (510Bhp) 2019 > Engine Cooling > Coolant Hoses and Pipes (Rear engine cars) >

Coolant Hoses - Radiator Section

Coolant Hoses - Radiator Section

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DISPLAYING 1 to 5 (of 5 products)
Breather Line, Cooler For Coolant. Porsche 982 / 982C / 991.2 2017>> - 9P1121465, 9P1121466
3
Breather Line, Cooler For Coolant. Porsche 982 / 982C / 991.2 2017>>
Special Order item
9P11214
Product Information
Product Information
Breather Line, Cooler For Coolant.
Ensure proper cooling system ventilation and pressure control with the Breather Line, Cooler for Coolant. This breather line is designed to route air and vapor from the coolant cooler system, helping maintain stable pressure and efficient coolant circulation under varying engine temperatures.  

Fits:
  • Porsche Boxster 718 2.0L Manual (300 Bhp) 2017>>
  • Porsche Boxster 718 2.0L PDK (300 Bhp) 2017>>
  • Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
  • Porsche Boxster S 718 2.5L PDK (350 Bhp) 05/2017>>
  • Porsche Boxster T 718 2.0L Manual (300 Bhp) 01/2019>>
  • Porsche Boxster T 718 2.0L PDK (300 Bhp) 01/2019>>
  • Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
  • Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
  • Porsche Boxster GTS 718 4.0L Manual (400 Bhp) 01/2019>>
  • Porsche Boxster GTS 718 4.0L PDK (400 Bhp) 01/2019>>
  • Porsche Boxster Spyder / Sypder RS 718 4.0L 01/2019>>
  • Porsche Boxster 25 Years 718 4.0L Manual (400 Bhp) 01/2020>>
  • Porsche Boxster 25 Years 718 4.0L PDK (400 Bhp) 01/2020>>
  • Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Carrera 2S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Carrera 4S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 2S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 4S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Targa 4S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Speedster 4.0L (510Bhp) 2019
  • Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
  • Porsche 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19
  • Porsche Cayman 718 2.0L Manual (300 Bhp)
  • Porsche Cayman 718 2.0L PDK (300 Bhp)
  • Porsche Cayman S 718 2.5L Manual (350 Bhp)
  • Porsche Cayman S 718 2.5L PDK (350 Bhp)
  • Porsche Cayman T 718 2.0L Manual (300 Bhp)
  • Porsche Cayman T 718 2.0L PDK (300 Bhp)
  • Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
  • Porsche Cayman GTS 718 2.5L PDK (365 Bhp)
  • Porsche Cayman GTS 718 4.0L Manual (400 Bhp)
  • Porsche Cayman GTS 718 4.0L PDK (400 Bhp)
  • Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L  

Diagram Ref No 20

What This Product Does:

  • Vents air and vapor from the coolant cooler system
  • Helps regulate cooling system pressure
  • Supports consistent coolant circulation
  • Reduces strain on hoses, seals, and cooling components

Symptoms Of Wear Or Failure:
  • Coolant leaks near the coolant cooler or hose connections
  • Sweet coolant smell from the engine bay
  • Coolant residue or staining around fittings and clamps
  • Cracked, brittle, or collapsed hose material
  • Loose or leaking hose connections
  • Gradual coolant loss requiring frequent top-offs
  • Pressure buildup in the cooling system (may cause swelling hoses)
  • Steam from under the hood in more severe cases
  • Engine temperature running higher than normal if coolant flow is affected

Why Replacement Matters:
  • Replacing a worn or damaged coolant cooler breather line is important because it helps the cooling system properly vent air and regulate pressure during normal engine operation. Over time, heat and constant exposure to coolant can cause the line to become brittle, cracked, or leak.
  • If the breather line fails, it can lead to coolant loss, pressure buildup, and added strain on surrounding hoses and seals. This may reduce cooling system efficiency and increase the risk of overheating or costly component damage.
  • Installing a new breather line helps prevent leaks, supports stable cooling performance, and protects the engine by maintaining proper system pressure and ventilation.



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

9P11214
9P1121465
9P1121466

The product you are viewing cross references to these numbers
Breather Line, Cooler For Coolant. Porsche 982 / 982C / 991.2 2017>> - 9P1121465, 9P1121466
3
Breather Line, Cooler For Coolant. Porsche 982 / 982C / 991.2 2017>>
9P11214
Product Information
Product Information
Breather Line, Cooler For Coolant.
Ensure proper cooling system ventilation and pressure control with the OE MATCH Breather Line, Cooler for Coolant. This breather line is designed to route air and vapor from the coolant cooler system, helping maintain stable pressure and efficient coolant circulation under varying engine temperatures.  

Fits:
  • Porsche Boxster 718 2.0L Manual (300 Bhp) 2017>>
  • Porsche Boxster 718 2.0L PDK (300 Bhp) 2017>>
  • Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
  • Porsche Boxster S 718 2.5L PDK (350 Bhp) 05/2017>>
  • Porsche Boxster T 718 2.0L Manual (300 Bhp) 01/2019>>
  • Porsche Boxster T 718 2.0L PDK (300 Bhp) 01/2019>>
  • Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
  • Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
  • Porsche Boxster GTS 718 4.0L Manual (400 Bhp) 01/2019>>
  • Porsche Boxster GTS 718 4.0L PDK (400 Bhp) 01/2019>>
  • Porsche Boxster Spyder / Sypder RS 718 4.0L 01/2019>>
  • Porsche Boxster 25 Years 718 4.0L Manual (400 Bhp) 01/2020>>
  • Porsche Boxster 25 Years 718 4.0L PDK (400 Bhp) 01/2020>>
  • Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Carrera 2S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Carrera 4S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 2S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Cabriolet 4S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
  • Porsche 991.2 Targa 4S / GTS 3.0L (420/450 Bhp) 2016-19
  • Porsche 991.2 Speedster 4.0L (510Bhp) 2019
  • Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
  • Porsche 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19
  • Porsche Cayman 718 2.0L Manual (300 Bhp)
  • Porsche Cayman 718 2.0L PDK (300 Bhp)
  • Porsche Cayman S 718 2.5L Manual (350 Bhp)
  • Porsche Cayman S 718 2.5L PDK (350 Bhp)
  • Porsche Cayman T 718 2.0L Manual (300 Bhp)
  • Porsche Cayman T 718 2.0L PDK (300 Bhp)
  • Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
  • Porsche Cayman GTS 718 2.5L PDK (365 Bhp)
  • Porsche Cayman GTS 718 4.0L Manual (400 Bhp)
  • Porsche Cayman GTS 718 4.0L PDK (400 Bhp)
  • Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L  

Diagram Ref No 20

What This Product Does:

  • Vents air and vapor from the coolant cooler system
  • Helps regulate cooling system pressure
  • Supports consistent coolant circulation
  • Reduces strain on hoses, seals, and cooling components

Symptoms Of Wear Or Failure:
  • Coolant leaks near the coolant cooler or hose connections
  • Sweet coolant smell from the engine bay
  • Coolant residue or staining around fittings and clamps
  • Cracked, brittle, or collapsed hose material
  • Loose or leaking hose connections
  • Gradual coolant loss requiring frequent top-offs
  • Pressure buildup in the cooling system (may cause swelling hoses)
  • Steam from under the hood in more severe cases
  • Engine temperature running higher than normal if coolant flow is affected

Why Replacement Matters:
  • Replacing a worn or damaged coolant cooler breather line is important because it helps the cooling system properly vent air and regulate pressure during normal engine operation. Over time, heat and constant exposure to coolant can cause the line to become brittle, cracked, or leak.
  • If the breather line fails, it can lead to coolant loss, pressure buildup, and added strain on surrounding hoses and seals. This may reduce cooling system efficiency and increase the risk of overheating or costly component damage.
  • Installing a new breather line helps prevent leaks, supports stable cooling performance, and protects the engine by maintaining proper system pressure and ventilation.



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

9P11214
9P1121465
9P1121466

The product you are viewing cross references to these numbers
Coolant Hose for Centre Radiator. Porsche 991.2 GT3 / GT3 RS / Speedster - 99110664991, 99110664891
3
Coolant Hose for Centre Radiator. Porsche 991.2 GT3 / GT3 RS / Speedster
Special Order item
99110664
Product Information
Product Information

Centre Radiator Coolant Hoses

These coolant hoses are designed for the centre radiator on the Porsche 991.2 GT3, GT3 RS and 991 Speedster. They form part of the high-performance cooling system used in Porsche’s naturally aspirated GT engines, ensuring coolant flows efficiently between the engine and the centre radiator.

Fits:

  • Porsche 991.2 Speedster 4.0L (510Bhp) 2019
  • Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19

Diagram Ref No 6 and 7 

High-revving GT models generate substantial heat, particularly during spirited driving and track use. Proper coolant circulation through the centre radiator helps maintain stable engine temperatures and supports consistent performance under demanding conditions.

What These Coolant Hoses Do

The Porsche 991.2 GT3 cooling system uses multiple radiators mounted at the front of the vehicle to manage engine temperatures. The centre radiator increases the system’s cooling capacity and helps remove excess heat from the coolant.

The hoses perform several important functions:

• Carry coolant to and from the centre radiator
• Maintain proper coolant circulation through the cooling system
• Help regulate engine temperature during high performance driving
• Support efficient heat transfer through the radiator core

Without properly functioning hoses, coolant flow may be restricted, reducing the effectiveness of the cooling system.

Why Coolant Hoses Fail

Cooling hoses operate under extreme conditions and are exposed to heat, pressure and vibration throughout their service life.

Common causes of failure include:

Heat ageing
 Continuous temperature cycles can cause rubber hoses to harden, crack or lose flexibility.

Pressure fatigue
 Cooling systems operate under pressure, which can weaken hoses over time.

Chemical degradation
 Coolant additives and contaminants can gradually break down rubber compounds.

Mechanical wear
 Engine movement and vibration may cause stress or abrasion on hose connections.

Symptoms of Failing Coolant Hoses

• Coolant leaks near the front of the vehicle
• Low coolant level warning messages
• Sweet coolant smell around the front bumper area
• Visible cracking or swelling of the hose
• Engine temperature fluctuations during driving

Replacing worn hoses helps maintain proper coolant flow and prevents sudden coolant loss.

Why You May Need to Replace These Hoses

Maintain Cooling System Efficiency
 Healthy hoses ensure coolant can circulate freely through the centre radiator and engine.

Prevent Coolant Leaks
 Replacing ageing hoses helps maintain the cooling system’s pressure and prevents leaks.

Protect the High-Performance GT Engine
 The GT3 and GT3 RS engines operate at high temperatures and require a fully functional cooling system.

Avoid Costly Engine Damage
 Loss of coolant can lead to overheating and significant mechanical damage if not addressed quickly.



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

99110664
99110664991
99110664891

The product you are viewing cross references to these numbers
O-Ring for Cooling System (46.7x3.53) - Several Applications. Porsche 987 / 981 / 718 / 996 / 997 / 991 - 99610680103
9
O-Ring for Cooling System (46.7x3.53) - Several Applications. Porsche 987 / 981 / 718 / 996 / 997 / 991
Special Order item
99610680103
Product Information
Product Information
O-ring – 46.7 x 3.53 – used in various applications within the car's cooling system.

Fits:
Porsche 987 Boxster 2005-12
Porsche 987 Cayman 2006-12

Porsche 981 Boxster 2012-16 
Porsche 981 Boxster Spyder 2016 
Porsche 981 Cayman 2014-16 
Porsche 981 Cayman GT4 2016 

Porsche 718 (982) Boxster 2017>> 
Porsche 718 (982) Boxster Spyder 2019>>
Porsche 718 (982) Cayman 2017>>
Porsche 718 (982) Cayman GT4 2019>>

Porsche 996 GT3 / RS 1999-05
Porsche 996 Turbo / GT2 2001-05

Porsche 997 Carrera 2005-12
Porsche 997 Turbo / GT2 RS 2007-13
Porsche 997 GT3 / RS 2007-11

Porsche 991 Carrera 2012-19
Porsche 991 Turbo / GT2 RS 2014-20
Porsche 991 GT3 / RS 2014-21

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

99610680103
99610680103

The product you are viewing cross references to these numbers
O-Ring for Cooling System (46.7x3.53) - Several Applications. Porsche 987 / 981 / 718 / 996 / 997 / 991 - 99610680103 - ORS161125
9
O-Ring for Cooling System (46.7x3.53) - Several Applications. Porsche 987 / 981 / 718 / 996 / 997 / 991
99610680103/1
Product Information
Product Information
O-ring – 46.7 x 3.53 – used in various applications within the car's cooling system.

Fits:
Porsche 987 Boxster 2005-12
Porsche 987 Cayman 2006-12

Porsche 981 Boxster 2012-16 
Porsche 981 Boxster Spyder 2016 
Porsche 981 Cayman 2014-16 
Porsche 981 Cayman GT4 2016 

Porsche 718 (982) Boxster 2017>> 
Porsche 718 (982) Boxster Spyder 2019>>
Porsche 718 (982) Cayman 2017>>
Porsche 718 (982) Cayman GT4 2019>>

Porsche 996 GT3 / RS 1999-05
Porsche 996 Turbo / GT2 2001-05

Porsche 997 Carrera 2005-12
Porsche 997 Turbo / GT2 RS 2007-13
Porsche 997 GT3 / RS 2007-11

Porsche 991 Carrera 2012-19
Porsche 991 Turbo / GT2 RS 2014-20
Porsche 991 GT3 / RS 2014-21

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

99610680103
99610680103

The product you are viewing cross references to these numbers
DISPLAYING 1 to 5 (of 5 products)
Also found on these pages
About Coolant Hoses - Radiator Section

Radiator Section Coolant Hoses – Mid & Rear-Engine Porsche Models

Radiator section coolant hoses are essential for managing engine temperature in mid and rear-engine Porsche models. These hoses circulate coolant between the engine and the radiator, ensuring consistent temperature control and preventing overheating under high-performance conditions.

At Design911, we stock a full range of genuine and manufacturer-quality radiator section coolant hoses specifically designed for mid- and rear-engine Porsche models such as the 911, Boxster, and Cayman. Each hose is built to factory specifications for perfect fitment, superior pressure tolerance, and reliable cooling system performance — ensuring your Porsche operates safely and efficiently on road or track.

What Do Radiator Section Coolant Hoses Do?

In Porsche’s mid- and rear-engine designs, coolant must travel a greater distance between the engine (located at the rear or middle) and the radiator (at the front). The radiator section hoses form part of this vital network, helping to:

  • Transport coolant efficiently from the engine to the front radiator.
  • Maintain optimal engine operating temperature for performance and longevity.
  • Regulate coolant flow through the entire system under varying loads.
  • Ensure consistent pressure and leak-free circulation.

These hoses are engineered to handle high thermal and mechanical stress, ensuring reliability even in extreme driving conditions.

Why Do Radiator Coolant Hoses Fail?

Due to their exposure to heat, pressure, and constant coolant flow, radiator section hoses can wear out over time. Common causes of failure include:

  • Material fatigue from heat cycles and pressure changes.
  • Cracks or splits in aging rubber or plastic connectors.
  • Corrosion or leaks around hose clamps and fittings.
  • Swelling or softening from prolonged coolant exposure.
  • Abrasion damage from rubbing against engine or chassis parts.

Symptoms of a failing coolant hose may include coolant leaks under the car, overheating, fluctuating temperature readings, or a low coolant warning light.

Why Replace Faulty Radiator Section Hoses?

A worn or leaking hose can cause coolant loss, overheating, and potential engine damage. Replacing aging hoses is an essential part of preventative maintenance — especially in mid- and rear-engine Porsche models, where efficient cooling is critical.

Benefits of replacement include:

  • Restored, leak-free coolant circulation.
  • Improved temperature control and system pressure.
  • Prevention of costly overheating and engine damage.
  • Manufacturer-quality materials for long-term reliability.

All replacement hoses in this range are constructed using reinforced, high-performance rubber compounds and precision-moulded fittings, ensuring durability, flexibility, and perfect compatibility with Porsche cooling systems.

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