Coolant Hoses - Centre Section

Breather Line.
Renew the ventilation path on your Porsche 911 (996-series) with these genuine breather / vent hoses. Designed for 1998-2005 911 (996) models (including Carrera, Turbo variants) these hoses ensure your engine’s breather or cooling-vent line operates correctly—preventing vapour or pressure buildup, supporting correct engine ventilation and maintaining system reliability.

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 996 TURBO 2000-05

Diagram Ref No 21 And 22

What This Product Does:

• In the context of the engine / cooling / ventilation system, a “breather line” or “vent hose / vent line” allows controlled venting of crankcase or cooling system gases, or supports the cooling/overflow/expansion system to relieve pressure, direct vapour, or provide required venting.
• These hoses ensure air or vapour that builds up is not trapped in the engine/cooling system, allow system pressure to stabilise, and maintain correct service behaviour of the engine’s ventilation or cooling circuits.
• They also help prevent buildup of pressure/vapour that could otherwise lead to malfunction, leaks or driveability issues.

Symptoms Of Wear, Damage Or When To Replace:

• Hose visible damage, cracking, brittleness or detachment — Over time, heat and age degrade rubber/hose materials.
  
• Engine or cooling system venting issues — for example, if you smell vapour/odour, see coolant or oil vapour escaping in unusual places, or lid caps popping off unexpectedly.
  
• Unusual noise or hissing from the engine bay or venting hose areas—possibly indicating a leak or damaged hose.
  
• Performance degradation in the ventilation/cooling system—such as elevated temperatures, pressure spikes in cooling, or increased oil consumption if the hose is a crankcase breather.
  
• Poor condition hoses in older vehicles—since these parts are often overlooked in maintenance, especially with older 996 models, they may be degraded and benefit from preventive replacement.
  
  

Why Replacement Matters:

• Maintains correct system function: A properly functioning breather line ensures your engine’s ventilation/cooling systems are working as intended — preventing pressure buildup, vapour trapping or system inefficiencies.
• Prevents secondary damage: A failing hose might lead to undue pressure or vapour escaping in unwanted places, which can damage hoses, connectors, engine seals or other vulnerable parts.
• Helps reliability and longevity: Especially in older 996 models, replacing old, brittle, cracked hoses with fresh OEM-spec units avoids failures that can strand the vehicle or lead to more expensive repair.
• Peace of mind & maintenance value: Ensuring the ventilation path is intact supports the overall health of the engine and cooling system, which can matter for resale or restoration quality.

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

99610676

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Cooling water pipe, feed.



Fits:
Porsche 996 C4 3.4L / 3.6L 1998-05
Porsche 996 Turbo 2001-05

Click 'Zoom in' for large parts diagram.
Diagram ref no 12

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99610675203

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HVAC Heater Hose - Feed

Maintain the efficiency and reliability of your Porsche's heating and cooling system with this HVAC Heater Hose (Feed)

Fits:

• Porsche 996 C2 3.6L 09/01-2005 (Tiptronic only)                 
• Porsche 996 C4 3.6L 09/01-2005 (Tiptronic only)     
• Porsche 996 C4S 3.6L 09/01-2005 (Tiptronic only)     
• Porsche 996 TURBO 2000-05
• 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
• Porsche 997 MK1 TURBO 2007-09
• Porsche 997 MK1 GT2 2007-09
• Porsche 997 MKII GT3 / GT3 RS 2010-11

Diagram ref no 17 

This genuine Porsche coolant hose forms an important part of the vehicle's HVAC (Heating, Ventilation and Air Conditioning) system by carrying hot engine coolant from the engine to the heater matrix (heater core). As coolant flows through the heater matrix, warm air is produced and directed into the cabin, providing rapid demisting, comfortable interior temperatures and helping the climate control system operate as designed.

Manufactured to Porsche's exact specifications, this Genuine Porsche heater feed hose offers the correct internal diameter, moulded shape and heat-resistant construction to ensure perfect fitment, unrestricted coolant flow and long-term reliability.

Whether replacing a leaking hose or carrying out preventative maintenance during cooling system repairs, choosing Genuine Porsche components ensures the quality and durability expected from the original factory installation.

What Does the HVAC Heater Feed Hose Do?

The heater feed hose transports hot coolant from the engine's cooling system to the heater matrix located inside the dashboard.

As engine coolant passes through the heater matrix, air is blown across it by the HVAC system, providing:

• Warm cabin heating
• Rapid windscreen demisting and defrosting
• Stable interior temperature control
• Efficient operation of the Porsche climate control system

The hose must withstand constant exposure to high coolant temperatures and system pressure while remaining flexible enough to accommodate engine movement and thermal expansion.

Why Do Heater Hoses Fail?

Like all rubber coolant hoses, heater hoses gradually deteriorate through age and continual exposure to heat, pressure and coolant chemicals.

Common causes of failure include:

• Rubber hardening with age
• Internal deterioration from coolant additives
• Heat cycling causing loss of flexibility
• Surface cracking and perishing
• Abrasion against surrounding components
• Swelling from oil or coolant contamination
• Corrosion around hose connections

As the hose ages, it becomes more susceptible to splitting or developing leaks, which can lead to coolant loss, reduced heater performance and, if ignored, engine overheating.

When Should the Heater Hose Be Replaced?

The HVAC heater feed hose should be inspected during every major service or whenever the cooling system is being maintained.

Replacement is recommended if you notice:

• Coolant leaks
• Dampness around the hose connections
• Cracked or perished rubber
• Bulging or swollen sections
• Soft or excessively hard hose material
• Sweet coolant smell from the engine bay
• Poor cabin heating caused by coolant loss
• During cooling system overhauls or engine-out servicing

Replacing ageing coolant hoses as preventative maintenance greatly reduces the risk of unexpected coolant loss and helps maintain the reliability of the engine and heating system.

Genuine Porsche Cooling & HVAC Components

The cooling and heating systems on your Porsche are designed to work together to regulate both engine temperature and cabin comfort. Every hose within the system plays an essential role in maintaining efficient coolant circulation and ensuring reliable operation under all driving conditions.

Because rubber coolant hoses naturally age over time, replacing them before failure is one of the most effective forms of preventative maintenance. A genuine Porsche hose guarantees the correct fit, material specification and durability required to withstand the demanding operating conditions of a high-performance engine.

Whether you're refreshing an ageing cooling system or undertaking a complete engine rebuild, fitting Genuine Porsche hoses provides peace of mind and helps preserve the long-term reliability of your vehicle.

Benefits of Replacing the Heater Feed Hose

• Restores reliable coolant circulation
• Improves cabin heating performance
• Supports rapid windscreen demisting
• Reduces the risk of coolant leaks
• Helps protect against engine overheating
• Direct Genuine Porsche replacement
• Ideal during cooling system servicing or preventative maintenance        

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

99610621275

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HVAC Heater Feed Hose – Feed

Restore the reliability of your Porsche's cooling and heating system with this OE Heater Feed Hose.

Fits:

• Porsche 996 C2 3.6L 09/01-2005 (Tiptronic only)          
• Porsche 996 C4 3.6L 09/01-2005 (Tiptronic only)     
• Porsche 996 C4S 3.6L 09/01-2005 (Tiptronic only)     
• Porsche 996 TURBO 2000-05
• 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
• Porsche 997 MK1 TURBO 2007-09
• Porsche 997 MK1 GT2 2007-09
• Porsche 997 MKII GT3 / GT3 RS 2010-11

Diagram ref no 17 

Designed to meet or exceed original equipment specifications, this high-quality replacement hose carries hot engine coolant from the engine to the heater matrix (heater core), enabling the HVAC system to provide efficient cabin heating, rapid windscreen demisting and consistent climate control performance.

Manufactured from premium automotive-grade rubber with reinforced construction, this OE Match hose is engineered to withstand the high temperatures, pressures and continual thermal cycling experienced within the Porsche cooling system. Offering excellent fitment and long-term durability, it provides an ideal replacement for ageing or deteriorated original hoses at a competitive price.

Whether you're repairing a coolant leak, refreshing the cooling system or carrying out preventative maintenance, replacing worn heater hoses helps maintain the reliability and efficiency of your Porsche.

What Does the Heater Feed Hose Do?

The heater feed hose forms part of the engine's coolant circuit, carrying heated coolant from the engine to the heater matrix located within the dashboard.

As warm coolant flows through the heater matrix, the vehicle's blower motor forces air across it before directing the heated air into the cabin. This allows the system to provide:

• Efficient interior heating
• Rapid windscreen demisting and defrosting
• Consistent climate control performance
• Comfortable cabin temperatures throughout colder months

Although relatively simple in design, the heater feed hose plays a vital role in both passenger comfort and the overall operation of the cooling system.

Why Do Heater Feed Hoses Fail?

Heater hoses operate in one of the harshest environments on the vehicle, continually exposed to high coolant temperatures, pressure fluctuations and engine vibration.

Over many years of service, the rubber gradually deteriorates due to:

• Constant heating and cooling cycles
• Age-related hardening and loss of flexibility
• Internal degradation caused by coolant additives
• Surface cracking and perishing
• Swelling from contamination
• Fatigue around hose ends and retaining clips
• Abrasion against surrounding engine components

As deterioration progresses, small coolant leaks can develop before eventually leading to hose failure and rapid coolant loss.

When Should the Heater Feed Hose Be Replaced?

Because coolant hoses naturally age over time, Porsche specialists often recommend inspecting them during every major service and replacing them whenever significant cooling system work is undertaken.

Replacement is advised if you notice:

• Visible coolant leaks or staining
• Cracked, brittle or hardened rubber
• Bulging or swollen sections
• Dampness around hose connections
• A sweet coolant smell after driving
• Reduced cabin heating performance
• During engine-out repairs or cooling system refurbishment
• As preventative maintenance on older vehicles

Replacing ageing heater hoses before they fail can help prevent unexpected coolant loss, reduce the risk of engine overheating and avoid costly roadside breakdowns.

Porsche Cooling System & Heater Hoses

The cooling system on your Porsche does far more than regulate engine temperature. It also supplies heated coolant to the HVAC system, ensuring efficient cabin heating, effective windscreen demisting and year-round driving comfort.

As rubber hoses age, they gradually lose their elasticity and structural integrity, making them increasingly susceptible to leaks and sudden failure. Replacing heater hoses as part of routine maintenance is a sensible investment that helps maintain the integrity of the entire cooling system while reducing the risk of overheating caused by coolant loss.

OE Match replacement hoses are manufactured to provide factory-style fitment, dependable performance and excellent value, making them ideal for both routine servicing and complete cooling system overhauls.

Benefits of Replacing the Heater Feed Hose

Restores reliable coolant circulation Maintains efficient cabin heating Improves windscreen demisting performance Reduces the risk of coolant leaks Helps protect against engine overheating OE Match quality with factory-style fitment Ideal for preventative maintenance on ageing vehicles

Whether you're carrying out a routine service, repairing a coolant leak or restoring your Porsche to its original condition, Design911 supplies the trusted parts you need to keep your vehicle performing at its best.

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

99610621275

The product you are viewing cross references to these numbers

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

The product you are viewing cross references to these numbers

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

The product you are viewing cross references to these numbers

Water coolant pipe FEED. 

Fits:
Porsche 986 Boxster S - 1999 to 2004

Porsche 996 - 1997 to 2005
Porsche 996 turbo - 2001 to 2005
Porsche 996 GT3 - 2000 to 2004

Diagram ref no 1

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99610661153

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