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Porsche Cayman 718C (982C) 2017>> Cayman GT4 RS Clubsport 2020-2024 Engine Cooling

Coolant Bottles / Expansion Tanks

Coolant Bottles / Expansion Tanks

DISPLAYING 1 to 1 (of 1 products)
Engine coolant filler neck lid. Porsche 981 / 982 Boxster / Cayman - 98110604406, 98110604405, 98110604404, 98110604403 - 981.106.044.06
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Engine coolant filler neck lid. Porsche 981 / 982 Boxster / Cayman
98110604406/1
Product Information
Product Information

Engine coolant filler neck lid
OE Match engine coolant filler neck lid for Porsche 981 and 982 Boxster and Cayman, including the specified Spyder, GT4 and Clubsport applications. This replacement closes the coolant filling access point.

Fits

  • Porsche 981 Boxster 2012 - 2016
  • Porsche 981SP Boxster Spyder 2016
  • Porsche 981C Cayman 2014 - 2016
  • Porsche 981 Cayman GT4 2016
  • Porsche 982 Boxster 2017 - 2024
  • Porsche 982C Cayman 2017 - 2024
  • Porsche 982 Spyder 2019 - 2024
  • Porsche 982 Cayman GT4 2019 - 2024

Diagram ref no 2

What This Product Does

The lid forms the closure at the coolant filling neck, covering the opening between servicing operations. It helps exclude debris and keeps the access area properly closed after coolant maintenance.


Functions

  • Closes the coolant filling opening.
  • Shields the access point against dirt.
  • Restores the closure when the previous lid is damaged or absent.
  • Allows the filling area to be closed again following service work.


Technical Details

  • Brand: OE Match.
  • Supplied part reference: 98110604406.
  • Identified in the supplied diagrams as a coolant end cap or water closure cap.
  • Located within the coolant reservoir and filling-neck assembly.


Symptoms of Fault

  • Visible cracks, distortion or broken sections.
  • A closure that sits loosely or cannot be refitted correctly.
  • An uncovered filling opening following loss of the lid.
  • Residue or debris around the access point requiring inspection.
  • Brittleness or damage discovered during reservoir maintenance.


Why Replacement Matters

Repeated handling, ageing and exposure to heat can leave the closure damaged or poorly seated. Renewing an unsuitable lid restores the intended closure of the filling access point. OE Match develops replacement components around Porsche applications, using original references and fitment checks to guide specification.

Inspect the adjoining neck before installation. Coolant loss or temperature warnings require diagnosis of the cooling system rather than assuming this access lid is responsible.


Reference Numbers

98110604406; 98110604405; 98110604404; 98110604403. Compare the vehicle's original reference and application details when selecting a replacement.


FAQs

Is it the expansion-tank pressure cap?
No. The supplied assembly diagrams distinguish this filling-neck closure from the separate reservoir pressure cap.

When should the lid be renewed?
Replace it if damaged, absent, distorted or unable to seat securely. Check the neck for related damage at the same time.



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

98110604406
98110604406
98110604405
98110604404
98110604403

The product you are viewing cross references to these numbers
DISPLAYING 1 to 1 (of 1 products)
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About Coolant Bottles / Expansion Tanks

Coolant Bottles / Expansion Tanks – Reliable Cooling Performance for Porsche Vehicles

Coolant bottles (also known as expansion tanks) are a vital part of your Porsche’s cooling system. They store excess coolant and manage pressure fluctuations as the engine heats up and cools down. By maintaining proper coolant levels and system pressure, they help prevent overheating, engine damage, and coolant loss - ensuring optimal performance and reliability.

At Design911, we offer a complete range of genuine and quality coolant bottles and expansion tanks for Porsche models including 911, Boxster, Cayman, Cayenne, Macan, and Panamera. Each tank is designed to deliver exact fitment, superior material strength, and long-term resistance to heat and pressure - matching the quality and precision of factory components.

What Do Coolant Bottles / Expansion Tanks Do?

The coolant bottle or expansion tank works as part of a sealed cooling system to:

  • Store and regulate excess coolant as temperatures and pressure fluctuate.
  • Maintain consistent pressure to prevent overheating or boiling.
  • Allow coolant recovery as the system cools, keeping the radiator full.
  • Provide a visible level indicator to monitor coolant condition and volume.

A properly functioning expansion tank ensures your engine operates at a stable temperature, improving efficiency and extending engine life.

Why Do Coolant Bottles Fail?

Coolant bottles are constantly exposed to heat, vibration, and pressure, which can cause degradation over time. Common causes of failure include:

  • Plastic fatigue or cracking from thermal cycling.
  • Coolant leaks around seams, caps, or hose connections.
  • Discolouration or brittleness from age and coolant exposure.
  • Faulty pressure caps leading to loss of system pressure.
  • Corrosion or contamination inside the tank.

Symptoms of a failing coolant bottle include visible coolant leaks, low coolant warnings, overheating, or pressure loss within the cooling system.

Why Replace Faulty Coolant Bottles / Expansion Tanks?

A damaged or leaking expansion tank can quickly lead to overheating, engine damage, or complete cooling system failure. Replacing it ensures safe, efficient operation and protects vital engine components.

Benefits of replacement include:

  • Restored coolant capacity and pressure stability.
  • Prevention of leaks and overheating.
  • Enhanced cooling system reliability and engine protection.
  • Factory-spec construction with manufacturer-level durability.

All replacement tanks are designed to meet or exceed factory standards using high-grade materials that resist cracking, corrosion, and deformation under extreme conditions

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