Coolant Hoses - Radiator Section

Centre Radiator Coolant Hose
These coolant hoses are designed for the centre radiator on the Porsche 991 Turbo, forming an important part of the high-performance cooling system used in Porsche’s twin-turbocharged flat-six engines.

Fits:

• Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
• Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
• Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
• Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19

Diagram Ref No 7 

The hoses ensure coolant flows correctly between the engine and the centre radiator, allowing excess heat to be dissipated efficiently. Maintaining proper coolant circulation is essential for protecting the engine from overheating and ensuring reliable performance under demanding driving conditions.

What These Coolant Hoses Do

The Porsche 991 Turbo cooling system uses multiple radiators positioned at the front of the vehicle to manage the large amount of heat generated by the turbocharged engine.

The centre radiator hoses perform several key functions:

• Carry coolant to and from the centre radiator
• Support proper coolant circulation through the cooling system
• Help regulate engine temperature under high load conditions
• Maintain efficient heat dissipation during spirited driving

Without these hoses functioning correctly, coolant flow may be restricted, reducing cooling efficiency and increasing the risk of overheating.

Why Coolant Hoses Fail

Cooling system hoses are constantly exposed to high temperatures, pressure and vibration. Over time these stresses can lead to deterioration.

Common causes of coolant hose failure include:

Heat ageing
Continuous heat cycles cause rubber hoses to harden and lose flexibility.

Pressure fatigue
Cooling systems operate under pressure, which can cause weakened hoses to swell or crack.

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

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

Symptoms of Worn or Failing Coolant Hoses

• Coolant leaks from the front of the vehicle
• Low coolant warning messages
• Sweet coolant smell near the front bumper area
• Rising engine temperatures
• Visible cracking, swelling or deterioration in the hose material

Replacing worn hoses helps prevent unexpected coolant loss and ensures the cooling system operates correctly.

Why You May Need to Replace These Hoses

Protect Engine Performance
The Porsche 991 Turbo engine generates significant heat, making reliable cooling system components essential.

Prevent Coolant Leaks
Replacing ageing hoses helps maintain system pressure and prevent leaks.

Maintain Cooling Efficiency
Healthy hoses ensure proper coolant flow through the centre radiator and the rest of the cooling system.

Prevent Costly Engine Damage
Overheating caused by coolant loss can lead to severe engine damage if not addressed quickly.

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99110664801

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Centre Radiator Coolant Hose
These coolant hoses are designed for the centre radiator on the Porsche 991 Turbo, forming an important part of the high-performance cooling system used in Porsche’s twin-turbocharged flat-six engines.

Fits:

• Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
• Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
• Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
• Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19

Diagram Ref No 6

The hoses ensure coolant flows correctly between the engine and the centre radiator, allowing excess heat to be dissipated efficiently. Maintaining proper coolant circulation is essential for protecting the engine from overheating and ensuring reliable performance under demanding driving conditions.

What These Coolant Hoses Do

The Porsche 991 Turbo cooling system uses multiple radiators positioned at the front of the vehicle to manage the large amount of heat generated by the turbocharged engine.

The centre radiator hoses perform several key functions:

• Carry coolant to and from the centre radiator
• Support proper coolant circulation through the cooling system
• Help regulate engine temperature under high load conditions
• Maintain efficient heat dissipation during spirited driving

Without these hoses functioning correctly, coolant flow may be restricted, reducing cooling efficiency and increasing the risk of overheating.

Why Coolant Hoses Fail

Cooling system hoses are constantly exposed to high temperatures, pressure and vibration. Over time these stresses can lead to deterioration.

Common causes of coolant hose failure include:

Heat ageing
Continuous heat cycles cause rubber hoses to harden and lose flexibility.

Pressure fatigue
Cooling systems operate under pressure, which can cause weakened hoses to swell or crack.

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

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

Symptoms of Worn or Failing Coolant Hoses

• Coolant leaks from the front of the vehicle
• Low coolant warning messages
• Sweet coolant smell near the front bumper area
• Rising engine temperatures
• Visible cracking, swelling or deterioration in the hose material

Replacing worn hoses helps prevent unexpected coolant loss and ensures the cooling system operates correctly.

Why You May Need to Replace These Hoses

Protect Engine Performance
The Porsche 991 Turbo engine generates significant heat, making reliable cooling system components essential.

Prevent Coolant Leaks
Replacing ageing hoses helps maintain system pressure and prevent leaks.

Maintain Cooling Efficiency
Healthy hoses ensure proper coolant flow through the centre radiator and the rest of the cooling system.

Prevent Costly Engine Damage
Overheating caused by coolant loss can lead to severe engine damage if not addressed quickly.

Related reference numbers
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99110664901

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Replacement coolant hose - connects to centre radiator
This radiator coolant hose forms part of the high-performance engine cooling system, helping circulate coolant through the front centre radiator to maintain stable engine operating temperatures. Designed for the first-generation 991 GT cooling arrangement, it provides a replacement for cracked, leaking or deteriorated original radiator hoses. Available separately for the left or right side.

Fits:
Porsche 991.1 GT3 / GT3 RS / R 2014-18

*Please be advised, this part is only compatible with first generation GT3 / GT3 RS models. If you have a second generation GT3 or GT3 RS, or a 991 GT3 Touring or Speedster, you must order 99110664991 and/or (LEFT) 99110664891 (RIGHT).

Diagram ref no 6 and 7

What This Part Does

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99110664

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Lower Feed and Return Coolant Hoses

These lower coolant hoses are designed for the side radiators on the Porsche 991 Turbo and form an essential part of the vehicle’s high-performance cooling system. The hoses carry coolant between the engine cooling circuit and the left and right radiators, ensuring that excess heat is efficiently dissipated during operation.

Fits:

• Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
• Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
• Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
• Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
• Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19

Diagram Ref No 9
 
Turbocharged Porsche engines generate significant heat under acceleration and high load conditions. Maintaining proper coolant circulation through all radiators is critical for protecting the engine and maintaining consistent performance.

What These Coolant Hoses Do

The Porsche 991 Turbo uses multiple front-mounted radiators to manage engine temperatures. The side radiators assist in removing heat from the coolant as it flows through the cooling system.

The lower feed and return hoses help:

• Deliver coolant from the engine to the side radiators
• Return cooled coolant back into the engine’s cooling circuit
• Maintain proper coolant circulation throughout the system
• Support stable operating temperatures during high performance driving

Without reliable coolant hoses, the system cannot properly transport coolant, reducing the efficiency of the radiators.

Why Coolant Hoses Fail

Cooling system hoses operate in harsh conditions and are exposed to continuous heat, pressure and vibration. Over time the materials degrade and can eventually fail.

Common causes include:

Heat degradation
Constant temperature cycling can cause the rubber to harden or crack.

Pressure fatigue
Cooling systems run under pressure which can weaken ageing hoses.

Coolant contamination
Old coolant or debris can damage the hose material internally.

Mechanical wear
Movement and vibration from the engine and chassis can stress the hose over time.

Symptoms of a Failing Coolant Hose

• Coolant leaks from the front of the vehicle
• Low coolant warning lights on the dashboard
• Sweet coolant smell from the front bumper area
• Visible swelling, cracking or deterioration in the hose
• Engine temperature fluctuations or overheating warnings

Replacing worn coolant hoses early prevents sudden coolant loss and protects the engine from overheating.

Why You May Need to Replace These Hoses

Maintain Cooling System Performance
Efficient coolant circulation ensures the radiators can properly remove heat from the engine.

Prevent Coolant Leaks
New hoses restore system integrity and maintain correct coolant pressure.

Protect the Turbocharged Engine
The Porsche 991 Turbo engine produces high heat levels, making cooling system reliability essential.

Prevent Costly Engine Damage
Overheating caused by coolant leaks can lead to serious mechanical damage if not addressed.

Related reference numbers
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99110663

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Engine coolant overflow / breather line.

Fits:
Porsche 991 Turbo / S 2014-20 - Excludes GT2 RS models
Porsche 991-1 GT3 / RS 2014-17

Diagram ref. 20.

NOTE: Our product image shows 99110686501, which is for the left side. 

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99110686

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Coolant radiator bottom hose, short.

Fits:
Porsche 991.1 Carrera 2012-16
Porsche 981 Boxster 2012-16
Porsche 981SP Boxster Spyder 2016
Porsche 981C Cayman 2014-16
Porsche 981 Cayman GT4 2016

Click 'Zoom in' for large parts diagram.
Diagram ref no 9

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99110662

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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

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99610680103

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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

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99610680103

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OE Match short radiator bottom return hose, left- and right-hand references identify the corresponding hose positions.

Fits

Porsche 991.1 Carrera 2012-16
Porsche 981 Boxster 2012-16
Porsche 981SP Boxster Spyder 2016
Porsche 981C Cayman 2014-16
Porsche 981 Cayman GT4 2016

Check fitment for your specific vehicle (model, year, engine) before ordering.

Diagram ref no 9

What This Product Does

This short hose forms the radiator's lower return connection within the coolant circuit. It carries returning coolant through the radiator-section pipework; it is distinct from the longer supply hoses shown in the assembly diagrams.

Functions

• Provides a passage for returning coolant.
• Connects the radiator return section to adjoining coolant pipework.
• Accommodates movement at the hose connection.
  
  

Technical Details

• Component: short coolant radiator bottom return hose.
• Left-hand reference: 99110662502.
• Right-hand reference: 99110662602.
• Brand: OE Match.
• Diagram positions vary by application; match the reference to the required side.
  
  

Symptoms of Fault

• Coolant pooling beneath the front or collecting on the undertray.
• Damp connections, staining or dried deposits around hose ends.
• A sweet odour accompanied by falling coolant level.
• Cracked, swollen or softened hose sections.
• Low-coolant warnings, gurgling or increased engine temperature.
  
  

Why Replacement Matters

Renewing a deteriorated or leaking return hose addresses coolant loss at that connection. Inspect adjoining fittings, seals and retaining hardware during the repair, since an unresolved connection fault can cause further seepage. OE Match's Porsche-focused replacement programme uses application and original-reference checks to identify suitable components.

FAQs

How do I select the correct side?
Match the original reference and diagram position: 99110662502 identifies the left hose; 99110662602 identifies the right hose.

Does front-end coolant leakage confirm hose failure?
No. Inspect the radiator and neighbouring joints too; a cooling-system pressure test can help locate the source.

Why might a leak appear intermittently?
Seepage can become apparent only as coolant temperature and system pressure increase.

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99110662

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Radiator coolant top hose, feed, long.

Fits:
Porsche 991 Carrera 2012-16
Porsche 981 Boxster 2012-16
Porsche 981 Boxster Spyder 2016
Porsche 981C Cayman 2014-16
Porsche 981C Cayman GT4 2016

Click 'Zoom in' for large parts diagram.
Diagram ref no 10

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99110662

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Radiator Coolant Vent Line, LEFT.

Ensure proper cooling system operation with the Radiator Coolant Vent Line, LEFT. This OE MATCH vent line is designed to help remove trapped air from the radiator cooling circuit, supporting consistent coolant circulation and stable engine temperature control.

Fits:

• Porsche Boxster 981 2.7L 2012-16
• Porsche Boxster 981 S / GTS 3.4L 2012-16
• Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
• Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
• Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
• Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
• Porsche Cayman 2.7L 981 2013-16
• Porsche Cayman S / GTS 3.4L 981 2013-16
• Porsche Cayman GT4 3.8L 2015-16  

Diagram Ref No 30

What This Product Does:

• Vents air from the radiator cooling system
• Prevents air pockets that can restrict coolant flow
• Supports consistent coolant circulation
• Helps maintain stable engine operating temperature
• Reduces the risk of overheating

Symptoms Of Wear Or Failure:

• Coolant leaks near the radiator or along the vent line
  
• Low coolant warning light or frequent coolant top-offs
  
• Sweet coolant smell from the front of the vehicle
  
• Coolant residue or staining around fittings or connections
  
• Cracked, brittle, or leaking vent line material
• Air trapped in the cooling system, causing gurgling sounds
  
• Fluctuating engine temperature or inconsistent gauge readings
  
• Overheating, especially after coolant service or refilling
  
• Steam from under the hood in severe cases
  
  

Why Replacement Matters:

• The radiator coolant vent line plays an important role in allowing trapped air to escape from the cooling system. If the line becomes cracked, brittle, or blocked, air pockets can form in the radiator circuit, reducing coolant flow and cooling efficiency.
• Failure to replace a damaged vent line may lead to coolant leaks, unstable system pressure, fluctuating engine temperatures, and an increased risk of overheating. Even small leaks can gradually reduce coolant levels and compromise performance.
• Replacing the vent line helps ensure proper system bleeding, maintains consistent coolant circulation, and protects the engine from heat-related damage.

Related reference numbers
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99110676502

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Radiator coolant vent line.

Fits:
Porsche 991.1 Carrera 2012-16
Porsche 981 Boxster 2012-16 incl. Boxster Spyder
Porsche 981C Cayman 2012-16 incl. Cayman GT4

Click 'Zoom in' for large parts diagram.
Diagram ref no 30

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99110676

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Radiator coolant vent line.

Fits:
Porsche 991.1 Carrera - 2012 to 2016
Porsche 981 Boxster - 2012 to 2016 incl. Boxster Spyder
Porsche 981C Cayman - 2012 to 2016 incl. Cayman GT4

Diagram ref no 30

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99110676602

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OE Match long-feed radiator top coolant hose, confirm the required side before ordering.

Fits

• Porsche 991 Carrera 2012-16
• Porsche 981 Boxster 2012-16
• Boxster 981 2.7L 2012–16
  
• Porsche 981 Boxster Spyder 2016
  
• Porsche 981C Cayman 2014-16
  
• Porsche 981C Cayman GT4 2016
  
  

Check fitment for your specific vehicle (model, year, engine) before ordering.

Diagram ref no 10

What This Product Does

This hose carries coolant along the radiator supply connection. It forms part of the circuit linking the radiator with the vehicle’s cooling pipework; it is the long feed version, rather than the short return hose.

Functions

• Provides a passage for coolant at the radiator feed connection.
• Connects the relevant radiator inlet to the adjoining coolant pipework.
• Accommodates movement at the flexible connection.
  
  

Technical Details

• Brand: OE Match.
• Configuration: long radiator supply hose, top connection.
• Left version reference: 99110662102.
• Right version reference: 99110662202.
• Diagram positions vary by application; match the reference and side rather than relying on the item number alone.
  
  

Symptoms of Fault

• Coolant collecting beneath the vehicle’s front end.
• Moisture or dried deposits at hose connections.
• A falling coolant level or dashboard level alert.
• A sweet odour near the radiator pipework.
• Cracks, bulging or unusually soft hose sections.
• Higher temperature readings or escaping steam.
  
  

Why Replacement Matters

A leaking or deteriorated feed hose can allow coolant to escape. Renewing a confirmed faulty hose addresses that source of fluid loss. Check adjacent fittings, clips and sealing surfaces during the repair, since damage elsewhere can cause leakage to recur. OE Match develops replacement components around Porsche applications, with reference matching and fitment assessment forming part of its product evaluation.

FAQs

How can I distinguish a hose leak from a radiator leak?
Inspect the hose ends alongside the radiator joints and end tanks. A cooling-system pressure test can help locate the source.

Why does leakage sometimes appear only after a journey?
A marginal connection may seep only while the cooling circuit is hot and pressurised.

Should the retaining hardware also be checked?
Yes. Inspect clips, clamps and adjoining fittings, replacing damaged or unsuitable components as required.

Related reference numbers
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99110662

The product you are viewing cross references to these numbers

Upper radiator hose. 

Fits:
Porsche 991 Turbo / S 2014-20 - Excludes GT2 RS
Porsche 991-1 GT3 / RS 2014-17

Diagram ref. 10.

NOTE: Our product image shows 99110663201, which is for the right-side radiator. 

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99110663

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Water coolant radiator top  hose, inlet.

Fits:
For cars with centre radiator (option code: 153)
Porsche 991.1 Carrera 2012-16
Porsche 981 Boxster 2012-16
Porsche 981C Cayman 2014-16

Click 'Zoom in' for large parts diagram.
Diagram ref no 6

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99110663802

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