The GEBA and Bosch water pumps do not include the rear housing (reuse the housing from the old water pump assembly). O-rings for the bypass pipe are serviced separately. It is STRONGLY recommended that these o-rings (part #90 537 379) also be replaced during water pump installation.
This Original Equipment Manufacturer part is the same part that was made & installed by the car manufacturer at the factory where the car was produced.
OE Replacement - 100% New
It is STRONGLY recommended to replace these 2 O-rings (part #90 537 379) for the pipe between the water pump and thermo. housing