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Porsche specialists based in the UK
Porsche Boxster 986/987/981 (1997-2016) Boxster S 986 3.2L 1999-02 Gearbox / Transmission Transmission Cooling

Pipes

Pipes

DISPLAYING 1 to 4 (of 4 products)
Coolant pipe, return. Porsche 986 Boxster 2000>> - 98630707721
3
Coolant pipe, return. Porsche 986 Boxster 2000>>
Special Order item
98630707721
Product Information
Product Information
Coolant pipe, return.

Fits:
Porsche 986 Boxster / Boxster S 2000>>
Tiptronic transmission

Click 'Zoom in' for large parts diagram.
Diagram ref no 21

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98630707721
98630707721

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Return line gearbox cooler. Porsche 986 Boxster / 987.1 Boxster / 987C.1 Cayman - 98630708505, 98630708504
3
Return line gearbox cooler. Porsche 986 Boxster / 987.1 Boxster / 987C.1 Cayman
Special Order item
98630708505
Product Information
Product Information
Return line gearbox cooler.

Fits:
For tiptronic transmission cars
Porsche 986 Boxster 1997-04
Porsche 987.1 Boxster 2006-08
Porsche 987C.1 Cayman 2006-08

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Diagram ref no 17

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Related, superseded, cross reference or alternative numbers for comparison.

98630708505
98630708505
98630708504

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Supply line gearbox oil cooler. Porsche 986 Boxster / 987.1 Boxster / 987C.1 Cayman - 98630708205, 98630708204
4
Supply line gearbox oil cooler. Porsche 986 Boxster / 987.1 Boxster / 987C.1 Cayman
Special Order item
98630708205
Product Information
Product Information
Supply line gearbox oil cooler

Fits:
For tiptronic transmission cars
Porsche 986 Boxster 1997-04
Porsche 987.1 Boxster 2006-08
Porsche 987C.1 Cayman 2006-08

Click 'Zoom in' for large parts diagram.
Diagram ref no 18

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Related, superseded, cross reference or alternative numbers for comparison.

98630708205
98630708205
98630708204

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Water Hose, 18 X 3,5 X 50. Porsche 986 Boxster / 987 Boxster / 987C Cayman - 90018106250, 90018106050
2
Water Hose, 18 X 3,5 X 50. Porsche 986 Boxster / 987 Boxster / 987C Cayman
Special Order item
90018106250
Product Information
Product Information

Water Hose, 18 X 3,5 X 50.
The Genuine Porsche Water Hose 90018106250 is a short coolant connector hose used within the water-cooling circuit associated with the Tiptronic automatic-transmission heat exchanger on selected Porsche Boxster and Cayman models.
Sold Each.
x2 Required Per Car.

Fits:

  • Porsche Boxster 986 2.5L 1997-99
  • Porsche Boxster 986 2.7L 1999-02
  • Porsche Boxster S 986 3.2L 1999-02
  • Porsche Boxster 986 2.7L 2003-04
  • Porsche Boxster S 986 3.2L 2003-04
  • Porsche Boxster 987 2.7L 2005-08/08
  • Porsche Boxster 987 S 3.2/3.4L 2005-08/08
  • Porsche Cayman 2.7L 987C 2006-08
  • Porsche Cayman S 3.4L 987C 2005-08  
Cars With Option Codes:
249 - Tiptronic Transmission

Diagram Ref No 11

Although positioned within the transmission-cooling system, this hose carries engine coolant rather than automatic transmission fluid.

Coolant circulating through the ATF heat exchanger transfers heat between the engine cooling system and the automatic transmission fluid, helping the transmission reach and maintain an appropriate operating temperature.

Because the hose operates as part of the pressurised engine cooling system, it must remain flexible, securely clamped and completely leak-free.

Age, heat, coolant exposure and repeated pressure cycles can eventually cause the rubber to harden, swell, crack or lose its ability to seal correctly.

Replacing a deteriorated hose helps restore coolant-system integrity and reduces the risk of coolant loss, transmission heat-exchanger problems and engine overheating.

What This Product Does:
This hose provides a short flexible coolant connection within the Tiptronic transmission oil-cooling circuit.

Its functions include:

  • Carrying engine coolant through the transmission heat-exchanger circuit.
  • Maintaining coolant circulation around the ATF cooler.
  • Helping regulate automatic-transmission fluid temperature.
  • Maintaining a sealed and pressurised cooling circuit.
  • Providing flexibility between adjoining rigid coolant components.
  • Accommodating vibration and thermal movement.
  • Preventing coolant loss at the connection.

Symptoms Of Wear Or Failure:
Common symptoms include:

  • Visible coolant leakage.
  • Coolant residue around the hose.
  • Damp hose connections.
  • Gradual loss of coolant.
  • Low-coolant warning.
  • Sweet coolant smell.
  • Drips beneath the vehicle.
  • Cracked rubber.
  • Hardened hose material.
  • Soft or swollen rubber.
  • Bulging.
  • Leakage around the hose clamps.
  • Engine temperature rising above normal.
  • Steam following a major coolant leak.

Why Replacement Matters:
Replacing a worn or leaking water hose helps restore:

  • Cooling-system sealing.
  • Correct coolant circulation.
  • Proper system pressure.
  • Reliable ATF heat-exchanger cooling.
  • Stable engine operating temperature.
  • Reduced risk of coolant loss.
  • Long-term cooling-system reliability.

A small coolant hose is inexpensive compared with the potential consequences of major coolant loss or overheating.



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

90018106250
90018106250
90018106050

The product you are viewing cross references to these numbers
DISPLAYING 1 to 4 (of 4 products)
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About Pipes

Porsche Transmission Coolant Pipes - Essential Gearbox Cooling Flow Components

Porsche transmission coolant pipes carry coolant between the gearbox, coolant control valves, and transmission oil coolers, ensuring consistent temperature regulation under all driving conditions. By maintaining correct coolant flow, these pipes protect transmission oil, seals, and internal components from overheating and premature wear.

Available from Design911, transmission coolant pipes are supplied to OEM specifications, making them suitable for maintenance, repairs, and complete cooling system refurbishments.

What Do Porsche Transmission Coolant Pipes Do?

Transmission coolant pipes form the physical flow network of the gearbox cooling system.

Core Functions:

  • Transport coolant to and from the transmission oil cooler
  • Maintain stable gearbox operating temperatures
  • Support efficient transmission oil cooling
  • Prevent thermal stress on internal gearbox components
  • Enable correct operation of coolant control and change over valves

Healthy coolant pipes are essential for reliable transmission thermal management.

Why Do Transmission Coolant Pipes Fail?

Transmission coolant pipes are exposed to heat, pressure, vibration, and environmental conditions.

Common Causes of Failure:

  • Corrosion in metal pipes from age or coolant degradation
  • Cracking or hardening of plastic and rubber sections
  • Heat cycling causing material fatigue
  • Leaks at pipe joints or O-ring connections
  • Physical damage from road debris or incorrect installation

Failure can result in coolant loss, overheating, and transmission damage.

When Should Transmission Coolant Pipes Be Replaced?

Porsche transmission coolant pipes should be inspected and replaced when signs of deterioration appear.

Replacement Indicators:

  • Visible coolant leaks or staining
  • Cracked, swollen, or brittle pipe sections
  • Repeated low coolant warnings
  • Overheating or inconsistent transmission temperatures
  • During transmission or cooling system servicing

Preventative replacement helps avoid sudden coolant loss and expensive gearbox repairs.

Highlights

  • Essential Porsche gearbox cooling system components
  • Maintains reliable coolant flow and temperature control
  • OEM-spec fitment and durability
  • Suitable for road, fast-road, and performance applications
  • Helps prevent overheating and premature gearbox wear       

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