Oil Coolers / Radiators / Heat Exchangers
Breather Hose. Porsche 996 / 997.1 1998-08
- 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
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.
- 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
The product you are viewing cross references to these numbers
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Engine oil cooler / heat exchanger tester for Porsche 996 / 997
- 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
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12

Some M96/M97 engines are experiencing oil-to-coolant intermixing. While there are potentially several sources of intermixing, faulty engine mounted oil-to-coolant heat exchangers are a major source. Now, with STOMSKI RACING's M96 Heat Exchanger Tester, you can confirm if your exchanger is faulty and needs replacing, or whether the source of the contamination is elsewhere. This high-quality tool is CNC machined from 6061 aluminum, anodized for years of service, and comes complete with all gauges, seals and hardware.
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Heat exchanger adapter for Porsche 996 / 997
- 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
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12

The compact, efficient design of the M96/M97 oil-to-coolant heat exchangers has proven itself useful for other than engine cooling. By remotely mounting M96/M97 exchangers, gearbox and/or steering rack temperatures can be reduced and the life of those components significantly extended.
STOMSKI RACING's M96 Heat Exchanger Adapter allows for convenient remote mounting and includes your choice of -6 or -8 AN fittings. This high-quality adapter plate is CNC machined from 6061 aluminum, anodized for years of service, and includes seals and hardware.
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Radiator oil cooler on engine. Porsche 996 / 997 / 986S
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- 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
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08

Fits:
Porsche 996 1998-05
Porsche 997 3.6L
Porsche 986 Boxster S 3.2L
Porsche 987 Boxster S 3.4L
Click 'Zoom in' for large parts diagram.
Diagram Ref No 18.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610702559
The product you are viewing cross references to these numbers
Shop Securely
12 Month Warranty
Worldwide Delivery
Radiator oil cooler on engine. Porsche 996 / 997 / 986S
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- 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
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08

Fits:
Porsche 996 1998-05
Porsche 997 3.6L
Porsche 986 Boxster S 3.2L
Porsche 987 Boxster S 3.4L
Click 'Zoom in' for large parts diagram.
Diagram Ref No 18.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610702559
The product you are viewing cross references to these numbers
Shop Securely
12 Month Warranty
Worldwide Delivery
Radiator oil cooler on engine. Porsche 996 / 997 / 986S
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- 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
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08

Fits:
Porsche 996 1998-05
Porsche 997 3.6L
Porsche 986 Boxster S 3.2L
Porsche 987 Boxster S 3.4L
Click 'Zoom in' for large parts diagram.
Diagram Ref No 18.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99610702559
The product you are viewing cross references to these numbers
Shop Securely
12 Month Warranty
Worldwide Delivery
Engine Oil Coolers, Radiators & Heat Exchangers – Precision Cooling for Porsche Performance
The engine oil cooler and heat exchanger system plays a critical role in managing temperature within your Porsche’s engine. By transferring excess heat away from the oil and other fluids, these components ensure stable operating temperatures, consistent lubrication, and maximum engine longevity — especially under demanding performance conditions.
At Design911, we offer a full range of engine oil coolers, radiators, and heat exchangers for Porsche models old and new. Built from high-efficiency aluminium or reinforced composite materials, these components are designed to deliver superior cooling performance, durability, and perfect fitment — ensuring your Porsche performs at its best, on road or track.
Whether replacing a worn-out unit or upgrading for improved thermal efficiency, our oil cooling components provide reliable temperature control and enhanced performance.
What Do Engine Oil Coolers, Radiators & Heat Exchangers Do?
These components regulate oil and engine temperatures to maintain optimal performance and prevent overheating.
Core Functions:
- Dissipate
excess heat from the engine oil, coolant, or transmission fluid.
- Maintain
consistent oil viscosity and prevent breakdown under load.
- Protect
internal engine components from heat-related wear and failure.
- Improve overall performance efficiency during extended drives or track sessions.
Together, the oil cooler, radiator, and heat exchanger form an essential thermal management system, helping your Porsche run at peak performance while protecting vital components.
Why Do Oil Coolers & Heat Exchangers Fail?
Over time, exposure to heat cycles, vibration, and contaminants can lead to efficiency loss or complete failure.
Common Causes of Failure Include:
- Corrosion
or cracking from age or road debris impact.
- Internal
clogging caused by sludge or contaminated oil.
- Leaking
seals or fittings, reducing pressure and fluid efficiency.
- Thermal
fatigue, leading to reduced cooling capacity.
- Poor maintenance or coolant neglect, accelerating deterioration.
Symptoms of failure can include high oil temperatures, oil leaks, coolant contamination, or reduced engine performance, all of which signal the need for inspection or replacement.
Why Replace Oil Cooling Components?
Replacing a worn or leaking oil cooler, radiator, or heat exchanger is essential to preserve lubrication quality and prevent costly overheating damage. Our precision-fit, high-durability components restore proper cooling balance and reliability under all conditions.
Key Benefits:
- Restores efficient oil and fluid temperature regulation.
- Prevents overheating and engine wear.
- Improves reliability under heavy load or track use.
- Constructed from corrosion-resistant, high-performance materials.
- Direct-fit compatibility for classic and modern Porsche engines.
- Ideal for rebuilds, maintenance, and performance upgrades.
Upgrading or replacing your cooling system components helps ensure your Porsche’s engine stays efficient, durable, and ready for spirited driving.
Highlights:
- Comprehensive range of Porsche oil coolers, radiators, and heat exchangers.
- Precision-engineered for consistent temperature control.
- Constructed from lightweight, corrosion-resistant materials.
- Designed for reliability in both road and motorsport conditions.
- Improves lubrication and protects engine performance.
- Perfect for maintenance, rebuilds, or performance enhancements.