Audi A4 B8 A5 8T Expansion Tank Header Coolant Reservoir Bottle 8K0121403AC

The Audi A4 B8 A5 8T Coolant Expansion Tank is an original cooling system component from the expansion tanks group, designed for use in popular mid-size Audi models. It's a practical solution for users who want to restore the proper functioning of their cooling system while maintaining the factory design and proven manufacturer solutions.

Specifications and technical data

• SKU: 8K0121403T
• Mark: Audi
• Condition: Used
• OEM Part Number: 8K0121403T
• Substitutable numbers: 8K0121403T, 8K0 121 403 T, 8K0121403AC, 8K0 121 403 AC
• Category: Expansion & Overflow Tanks

Technical Characteristics of the Audi Expansion Tank

The presented tank belongs to the Expansion Tanks category and has been specifically designed for Audi vehicle cooling systems. The tank's construction allows for stable coolant level maintenance, compensation for volume changes during heating, and safe release of excess system pressure.

Its original Audi OE origin ensures correct connector geometry, appropriate mounting points, and compatibility with factory hoses and accessories. This allows the tank to work with sensors and cooling system components as intended by the vehicle manufacturer.

Purpose and Application in Audi A4 B8 / A5 8T Models

The Audi A4 B8 A5 8T Coolant Expansion Tank has been developed for installation in the engine bay of A4 B8 and A5 8T models, where space and hose routing are strictly defined. Using an original tank allows for maintaining:

• correct positioning relative to the radiator and engine,
• proper coolant flow throughout the system,
• factory mounting points and hose routing.

Consequently, replacing the component does not require any installation modifications, and the cooling system regains stable operating conditions, which is crucial for both engine durability and driving comfort.

Benefits of Using an Original Expansion Tank

Using an original Audi OE tank to replace a worn or damaged component offers a range of practical benefits:

• Factory Fitment – maintaining the original geometry and connector positioning simplifies installation and minimizes the risk of leaks.
• System Compatibility – the tank works with factory hoses, cap, and accessories without the need for adaptations.
• Stable Engine Operation – a properly functioning expansion tank helps maintain the optimal operating temperature, contributing to the powertrain's longevity.

This solution is particularly beneficial for users who want to preserve the cooling system's design as per the manufacturer's specifications, without compromising on fit and functionality.

Product Condition and Practical Installation Aspects

The offered component comes from the used Audi parts segment, allowing for an attractive price while retaining the original construction. The tank is intended for installation as a replacement for the factory-fitted part, utilizing existing mounting points and hoses in the engine bay.

In practice, installation involves disconnecting the old tank, transferring the hoses, and refilling the system with the appropriate coolant, following the bleeding procedures specified for the particular Audi model. This approach restores correct cooling system operation without altering its structure.

More Expansion Tanks and Knowledge About Used Parts

If you are looking for other Audi expansion tanks compatible with various models of this brand, check out our offer in the Audi expansion tanks category, where you will find a wide selection of cooling system components.

Do you have doubts about choosing parts from the secondary market and want to better understand how to wisely use used components? Read the article Used Car Parts: Myths and Facts You Need to Know to make informed purchasing decisions and effectively manage your car's service costs.