Engine Water Pump BMW F80 M3 F82 M4 S55 Coolant Water Unit 7846361

Engine Water Pump BMW F80 M3 F82 M4 S55 Coolant Water Unit is an original component from the Water Pumps group, designed for S55 petrol engines in BMW M-series sports models. This used OEM part ensures a factory fit, maintaining the correct coolant circulation parameters and stable engine operating conditions during dynamic driving.

Specifications and technical data

• SKU: 7846361-1
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7846361
• Substitutable numbers: 7846361, 11517846361
• Fuel type: Petrol
• Category: Water Pumps

Purpose and function in the cooling system

The water pump in the S55 engine is responsible for the forced circulation of coolant between the engine block, cylinder head, and heat exchangers. In high-performance petrol units, such as the F80 M3 and F82 M4, the proper operation of the pump is crucial for maintaining a stable operating temperature, protecting against overheating, and preserving consistent performance.

The original BMW design is optimized for flow characteristics, compatibility with the engine control system, and the specific thermal loads typical of the S55 unit. As a result, the pump works with the factory thermostat, radiator, and other cooling system components without the need for modifications.

Benefits of using an original BMW pump

Using a factory water pump in M sports models provides a number of practical technical benefits:

• Full compatibility with the S55 engine – maintaining factory flow and pressure parameters in the cooling system.
• Stable operation across a wide load range – from daily use to intensive track driving.
• Proper cooperation with electronic control systems and temperature sensors.
• Reduced risk of incorrect installation due to serial geometry and mounting points.

For high-power petrol units like the S55, using an original water pump is particularly important for engine durability and maintaining predictable thermal conditions under all operating circumstances.

Condition, origin, and fitment

The offered pump belongs to the group of used BMW OEM components, which means it is of factory origin and designed in accordance with the manufacturer's requirements. This type of part is a good choice for cooling system maintenance when you want to maintain the original specification without resorting to replacements with uncertain parameters.

To correctly select a pump for a specific F80 M3 or F82 M4, it is worth verifying compatibility by the OEM number or interchangeable numbers based on service documentation or a parts catalog. This helps avoid installation problems and ensures proper cooperation with other cooling system components.

Operation in petrol engines and service tips

In S55 petrol units, the water pump operates under high thermal load conditions, so it is worth considering checking or replacing it during any major cooling system work (e.g., replacing the radiator, hoses, or thermostat). Symptoms such as an increase in operating temperature, uneven heating, coolant leaks, or unusual noises from the pump drive area may indicate the need for service intervention.

Regular coolant replacement according to the manufacturer's recommendations and ensuring system tightness significantly extend the pump's service life. When installing a used component, it is crucial to properly bleed the system and check all connections for potential leaks.

If you are planning a comprehensive repair or upgrade of your BMW's engine area and need other elements from the same group, such as auxiliary pumps, fluid circulation elements, or cooling support components, check the available parts in the BMW Water Pumps category.

For a better understanding of the relationship between the cooling system and engine power supply, as well as the impact of operating temperature on engine durability, it is worth reading the guide on our blog: Fuel system – injectors, pumps, and fuel tank: maintenance and regeneration. In the article, you will find practical tips on diagnostics, selecting parts by OEM numbers, and proper operating principles.

If you are interested in the broader context of using specialized components in M models and the differences between M-series components and standard versions, the following post may also be helpful: BMW M Performance: how do BMW M components differ from standard ones?. This will make it easier for you to assess when it is worth choosing original, used parts dedicated to BMW sports variants.