Audi A8 S8 D3 Coolant Expansion Reservoir Water Tank Bracket 5.2 FSI 4E0121424B

Audi A8 S8 D3 Coolant Expansion Reservoir Water Tank Bracket is an original mounting component designed for the cooling system in gasoline-powered vehicles. It ensures stable seating of the expansion reservoir, which translates into safe cooling system operation and proper fluid circulation under demanding operating conditions. This is a practical solution for users who want to maintain the factory mounting geometry and avoid makeshift repairs.

Specifications and technical data

• SKU: 4E0121424B
• Mark: Audi
• Condition: Used
• OEM Part Number: 4E0121424B
• Substitutable numbers: 4E0121424B, 4E0 121 424 B
• Fuel type: Petrol
• Part type: Coolant Expansion Tank
• Category: Expansion & Overflow Tanks

Purpose and function in the cooling system

The presented bracket is a component from the Expansion Reservoirs group and is responsible for the precise mounting of the reservoir in the engine bay. In Audi A8 / S8 D3 class vehicles with the 5.2 FSI unit, the stable position of the reservoir is important for:

• maintaining the correct coolant level during acceleration and braking,
• reducing vibrations and stress acting on the connectors and hoses,
• maintaining connection tightness during long-term operation,
• easy service access to the reservoir during inspection and fluid refilling.

Thanks to its factory design, the bracket works with the original expansion reservoir, maintaining the position designed by the manufacturer relative to other cooling system components.

Compatibility with the 5.2 FSI (gasoline) unit

The bracket has been designed for Audi cars with a high-displacement FSI gasoline engine, where the cooling system operates under significant thermal load. The mounting design takes into account:

• the layout of components in the engine bay typical for the 5.2 FSI version,
• routing of cooling hoses and their stress relief in the reservoir area,
• appropriate rigidity to limit reservoir movement at high speeds and during dynamic driving.

Selecting the correct bracket for a specific engine version is crucial to avoid stress on the reservoir connectors and potential leaks in the cooling system.

Characteristics of the original Audi part

As an Audi brand component, the expansion reservoir bracket has been manufactured in accordance with the vehicle manufacturer's requirements regarding durability and fitment. This means that:

• the mounting geometry corresponds to the factory mounting points on the body,
• the material has been selected for resistance to temperature in the engine bay and exposure to operating fluids,
• there is no need for modifications or adaptations – the component works with original bolts and hardware.

This type of solution is particularly beneficial for repairs of premium class vehicles, where maintaining structural and service consistency is essential.

Condition, application, and benefits of installation

The offered bracket comes from the used parts group, which allows for economical repair without giving up the original Audi design. Replacing a damaged or deformed mount with a functional element of this type helps to:

• restore the correct position of the expansion reservoir relative to the engine and body,
• reduce the risk of connector cracks and hose leaks,
• maintain stable cooling system operation in both city and highway conditions.

This is a practical solution for both post-accident repairs and for addressing the effects of material fatigue after years of operation.

Expanding the Audi cooling system – selecting related components

If you are planning a comprehensive repair or upgrade of the engine area in your Audi and need other elements from the same group, such as additional brackets, mounts, or supports for the cooling system, check the available parts in the Audi Expansion Reservoirs category.

To better plan your repair budget and make informed choices when selecting original recycled parts, it is worth reading practical tips on choosing used components – the article Brake calipers under the microscope: How to effectively reduce repair costs by choosing proven recycled parts will be helpful, as it shows how to safely use recycled parts in other vehicle systems as well.