Porsche 718 Boxster Cayman 982 Coolant Expansion Tank 982121407B

Porsche 718 Boxster Cayman 982 Coolant Expansion Tank is an original cooling system component designed for the 718 Boxster and Cayman model series. It ensures stable engine operation by monitoring coolant levels and compensating for volume changes, which is particularly important in sports cars such as Porsche. Thanks to its factory origin, the expansion tank maintains the correct connection geometry and compatibility with the stock installation.

Specifications and technical data

• SKU: 982121407B
• Mark: Porsche
• Condition: Used
• OEM Part Number: 982121407B
• Substitutable numbers: 982121407B, 982 121 407 B
• Part type: Reservoir
• Category: Washer Pumps, Reservoirs & Nozzles

Purpose and function in the cooling system

The expansion tank in the Porsche 718 Boxster and Cayman is responsible for the safe discharge of excess coolant and its return to the circuit after the temperature drops. A properly selected component:

• stabilizes pressure in the cooling system during dynamic driving,
• allows for visual inspection of the fluid level,
• reduces the risk of engine overheating,
• ensures proper cooperation with the pressure cap and hoses.

By maintaining factory design parameters, the expansion tank works seamlessly with the stock coolant pump, hoses, and sensors, which translates into predictable system behavior across the full load range.

Original origin and Porsche compatibility

The presented tank comes from the Porsche product range, which means it adheres to the vehicle manufacturer's quality standards. The original component:

• is matched to the factory mounting points in the engine bay,
• has the correct shape of connection ports,
• ensures compatibility with stock clamps and coolant hoses.

As a result, installation is predictable, without the need for system modifications, and the cooling system retains parameters close to the factory configuration, which is essential for both road and track use.

Performance characteristics of the used component

The item is offered in a used condition, which allows for an economical repair of the cooling system while maintaining the manufacturer's original specifications. In practice, this means the possibility of:

• restoring system tightness in the event of damage to the existing tank,
• maintaining factory fitment without the risk of dimensional differences typical for non-OEM replacement parts,
• reducing service costs while maintaining high build quality.

Choosing a used expansion tank is particularly beneficial in situations where the existing component has cracked, suffered thermal deformation, or shows leaks at the connection ports.

Technical support, part number selection, and service knowledge

The offered expansion tank has an assigned OEM part number and interchangeable numbers, which facilitates precise identification and selection for a specific version of the Porsche 718 Boxster or Cayman. In case of doubt, it is worth consulting service documentation or a mechanic specializing in the brand to confirm compatibility with the model year and engine variant.

For users interested in a broader context of selecting and operating fluid system components, an article describing the principles of diagnostics, identification by OEM numbers, and proper component maintenance may be helpful – detailed information can be found in the material Fuel system – injectors, pumps, and fuel tank: maintenance and regeneration, which discusses, among other things, good service practices and the approach to part numbering.

Comprehensive service for Porsche fluid systems

If you are planning a comprehensive repair or upgrade of the fluid system area in your Porsche and need other elements from the same group, such as additional tanks, pumps, or fluid nozzles, check out the available parts in the category Porsche washer fluid tanks, pumps, and nozzles.

When deciding to use a used part, it is also worth analyzing the differences between new and aftermarket components in terms of cost and durability – a helpful comparison can be found in the article Car parts – new or used? We compare costs, quality, and durability, which discusses the practical aspects of choosing service solutions.