BMW F20 F21 F30 F31 LCI B38 B48 Petrol Engine Thermostat Water Pump 7644811

Visual condition of the part 

The product shows signs of use visible in the photos. 

BMW F20 F21 F30 F31 LCI B38 B48 Petrol Engine Thermostat Water Pump is an original component from the Water pumps group, designed for B38 and B48 petrol engines in F20, F21, F30, and F31 LCI (facelift) body versions. This solution allows for the restoration of proper coolant circulation and stable engine operating temperature, which translates into safe and reliable powertrain operation.

Specifications and technical data

• SKU: 7644811-4
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7644811
• Substitutable numbers: 7644811, 11537644811
• Fuel type: Petrol
• Category: Water Pumps

Purpose and function in the cooling system

The presented thermostat integrated with the water pump is a component of the cooling system for B38/B48 petrol engines used in compact and mid-size BMW 1 Series and 3 Series models after the LCI update. It is responsible for forcing coolant circulation and controlling the operating temperature, which is crucial for the durability of the engine, performance stability, and fuel consumption reduction.

Combining the water pump and thermostat functions into a single assembly allows for precise management of coolant temperature, thereby maintaining optimal engine operating conditions across various load ranges and engine speeds.

Benefits of using an original BMW water pump

Using an original BMW solution in the cooling system ensures:

• proper cooperation with the engine control electronics and temperature maps,
• appropriate coolant flow characteristics across the entire RPM range,
• consistency with the factory cooling system architecture in F20, F21, F30, and F31 LCI models.

As a result, the factory heating and cooling characteristics of the engine are maintained, which limits the risk of overheating, local thermal stresses, and accelerated wear of mating components.

Component condition and practical service application

The offered thermostat and water pump assembly is an aftermarket part in Used condition, making it an attractive cost-effective alternative while maintaining the original design. This type of component is particularly useful for:

• cooling system repairs following a pump or thermostat failure,
• resolving issues with unstable engine operating temperature,
• preventive maintenance in higher-mileage vehicles, where replacing components responsible for coolant circulation is recommended.

Selecting parts according to the manufacturer's markings and engine generation ensures full installation and functional compatibility with the factory system.

Significance for B38/B48 petrol engines

In modern BMW petrol units, such as the B38 and B48, stable temperature management has a direct impact on the durability of the turbocharger, lubrication system, and internal engine components. A functional thermostat with a water pump:

• maintains the correct operating temperature range in both city and highway conditions,
• supports the proper operation of the mixture and ignition control system,
• reduces the risk of overheating during high-load situations.

For users who expect predictable vehicle behavior and want to avoid costly engine repairs, a functional water pump and thermostat assembly is one of the key elements in keeping the engine in good condition.

Selection support and additional materials

When selecting powertrain and cooling system components, it is worth using the manufacturer's markings and catalog data to ensure full compatibility with the specific engine and body version. Additional information on diagnostics, selection based on manufacturer markings, and maintenance of power supply and engine control components can be found in the article Fuel system – injectors, pumps, and fuel tank: maintenance and regeneration, which organizes service knowledge in one place.

If you are planning a comprehensive repair or upgrade of your BMW engine area and need other components from the same group, such as housings, connectors, or additional modules related to the coolant circuit, check the available parts in the BMW Water pumps category.