4h0121403g Expansion Tank - Online wholesale prices

The 4H0121403G is an expansion tank for the engine coolant system, typically used in Audi and Volkswagen vehicles, especially those from the Audi A6 and A7 series. The expansion tank is crucial for the cooling system of the engine, helping to maintain pressure and accommodate the expansion of coolant as it heats up.

Key Features:

• Function: The expansion tank serves as a reservoir for coolant, maintaining the optimal pressure within the cooling system. It also provides space for the coolant to expand when the engine gets hot and contracts as it cools down.
• Material: Usually made from high-strength plastic to withstand the heat and pressure in the engine bay. Some versions may have a metal cap or a reinforced structure for added durability.
• Location: Positioned near the radiator or in the engine bay, typically at the highest point of the cooling system for easy coolant level monitoring.
• Cap and Sensor: It is usually equipped with a pressure cap and sometimes a level sensor to alert the driver if the coolant level is low or the system is experiencing issues.

Compatibility:

• Primarily designed for Audi and VW models, particularly those using 3.0L V6 or similar engines, though it may fit a range of models from the Audi A6, A7, and Q5 series, as well as certain Volkswagen vehicles.

Importance:

The expansion tank helps prevent the engine from overheating by maintaining the appropriate coolant pressure and level. A failure or crack in the expansion tank can lead to coolant loss, which can cause the engine to overheat or suffer damage.

When replacing or inspecting the expansion tank, it's important to ensure that the cap is functioning properly and that there are no leaks in the system.