Mercedes W221 Coolant Expansion Tank Reservoir Bottle Fluid Tank A2215000349

Mercedes W221 Expansion Tank A2215000349 is an original cooling system component from the expansion tank group, designed for use in S-Class W221 models. This used OEM component ensures proper pressure and a stable coolant level, contributing to safe engine operation across a wide range of loads.

Specifications and technical data

• SKU: A2215000349
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A2215000349
• Substitutable numbers: A2215000349, A 221 500 03 49
• Category: Expansion & Overflow Tanks

Function and Role in the Cooling System

The expansion tank in the Mercedes W221 is responsible for compensating for changes in coolant volume due to temperature fluctuations. A properly selected component:

• stabilizes pressure in the cooling system,
• allows for easy coolant level monitoring,
• reduces the risk of engine overheating,
• supports even fluid distribution throughout the circuit.

By using an original expansion tank, the factory characteristics of the cooling system are maintained, which is particularly important for premium vehicles like the Mercedes S-Class.

Compatibility and Identification Parameters

The presented expansion tank has been specifically designed for the W221 platform, retaining factory mounting points and hose connections. Appropriate manufacturer markings, including the dedicated OEM part number and available replacement numbers, facilitate unambiguous identification and selection of the correct component for a specific engine version.

Additionally, the product has an assigned SKU, allowing for efficient searching and order processing in warehouse systems and parts configurators.

Product Condition and Service Application

The component is offered as a used part, which is a cost-effective solution for routine repairs and restoring the cooling system's functionality in vehicles with higher mileage. Replacing the expansion tank is recommended in cases of:

• visible cracks or leaks in the housing,
• problems maintaining the coolant level,
• damage to the connection spigots,
• corrosion or wear of cooperating elements (e.g., cap, spigots, clamps).

Choosing an original expansion tank for the Mercedes W221 helps minimize the risk of incompatibility, typical of universal aftermarket replacements, and simplifies installation in factory mounting points.

Benefits of Using an Original Expansion Tank

Using a dedicated expansion tank for the Mercedes W221 offers a range of practical service and operational benefits:

• Factory Fitment – maintains original geometry, spigot diameters, and mounting locations.
• Cooling System Cohesion – compatible with hoses, sensors, and other system components.
• Hassle-Free Installation – no need for modifications to the system or custom bracket fabrication.
• Stable Engine Operation – ensures proper coolant circulation and maintenance of correct operating pressure.

For workshops and individual users, this translates to shorter repair times, reduced risk of complaints, and maintenance of operating parameters consistent with the vehicle manufacturer's specifications.

Selecting Other Mercedes Expansion Tanks

If, during cooling system service, you are considering replacing other components and are interested in additional solutions dedicated to this brand, check the available parts in the Mercedes Expansion Tanks category.

To compare the characteristics of sports powertrains with solutions used in standard versions, and to better understand the construction differences within a single brand, it is worth reading the material discussing powertrains and chassis in RS models – details can be found in the article Audi RS vs. Other Models – What's Under the Hood and Chassis?.