Mercedes W208 W209 W220 Water Pump Thermostat Housing A1122030275

Mercedes W208 W209 W220 Water Pump Thermostat Housing is an original cooling system component from the Thermostats and housings group, designed for M112 series engines. The use of a factory design ensures proper coolant circulation and stable thermostat operation, which translates into safe operating conditions for the power unit. This is a solution for users looking for a proven component with preserved mounting geometry and correct functionality.

Specifications and technical data

• SKU: A1122030275
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A1122030275
• Substitutable numbers: A1122030275, A 112 203 02 75
• Category: Thermostats & Housings

Function and application in the cooling system

The water pump integrated with the thermostat housing in M112 engines is responsible for forced coolant circulation and operating temperature control. A properly selected component helps maintain stable thermal conditions, reduces the risk of overheating, and supports even heating of the entire engine block. For E24, E26, and E28 units, the proper cooperation of the pump with the thermostat is crucial for the durability of seals, cylinder heads, and accessories.

Construction and fitment for M112 engines

The thermostat housing connected to the water pump body is designed to precisely fit the cooling system of M112 engines. Properly shaped flow channels direct coolant to critical areas of the block and heads, while the integrated thermostat seat allows for its correct seating and tight closure of the system. Thanks to the preservation of factory mounting points, installation is predictable, without the need for modifications or adjustments.

Benefits of using an original water pump with thermostat housing

Using an original component instead of a worn or leaking part brings measurable operational benefits. The most important include:

• maintaining the proper engine operating temperature across a wide range of loads,
• stable coolant flow at high engine speeds,
• reducing the risk of local overheating and cavitation in the system,
• preserving the factory thermostat opening characteristics,
• proper fitment with other cooling system components.

For the user, this means more predictable power unit operation, less stress on other components, and the possibility of continued operation without costly engine interventions.

Component condition and installation aspects

The offered water pump with thermostat housing is an aftermarket component, which allows for optimizing repair costs while maintaining the factory design. Before installation, standard workshop procedures are recommended: checking mating surfaces, verifying seal seats, and checking the free rotation of the impeller. Replacement should be combined with the use of new gaskets and the addition of fresh coolant in accordance with the vehicle manufacturer's specifications.

Technical support and part selection

The component should be selected based on vehicle data and information contained in the specification, such as engine designation and catalog parameters. In case of doubt, it is worth comparing the shape of the body, the arrangement of the connectors, and the mounting points with the currently installed unit. This minimizes the risk of error and shortens the vehicle's downtime in the workshop.

If you are planning a comprehensive repair or upgrade of the engine area in your Mercedes and need other elements from the same group, such as thermostat housings, water pump bodies, or related cooling system components, check the available parts in the Mercedes Thermostats and housings category.

To compare service costs and the impact of power unit design on durability and repair profitability, you can read an article describing the evolution of Volkswagen engines – Volkswagen 1.9 TDI vs 1.4 TSI – evolution of VW engines and repair costs. This will allow you to better assess the importance of proper selection of used components in long-term vehicle operation.