The water pump has a big job to do. It has to use the engine torque from the drive belt to circulate huge amounts of coolant throughout the motor and radiator. With so many internal forces at play, the bearings can fail with almost no notice at all, creating leaks. The other main weakness is that the original factory BMW water pumps use a plastic impeller, which can degrade over time, resulting in bits of debris running through the motor. Manufactured by HEPU, this water pump has a lightweight metal impeller for greater longevity and reduced resistance. Made in Germany, and complete with rubber o-ring. 

OEM Part Number: 11517527910
Alternative Part Number: 11517527799
Alternative Part Number: 11511433828
Alternative Part Number: 11511740241
Alternative Part Number: 11517509985
HEPU Part Number: P472