Diesel engine water pump with improved water seal

A water pump of the centrifugal type adapted for use in diesel engine cooling systems, the water pump comprising:

• a housing containing a shaft rotatable on an axis extending through the housing, the shaft mounting a drive member adjacent a drive end of the housing and a fluid impeller at an opposite impeller end of the housing;
• axially spaced drive and impeller roller bearings mounted in an oil lubricated recess and supporting the shaft in the housing, each bearing having an inner race fixed on the shaft and an outer race mounted in the housing, the outer race of the drive bearing being fixed in the housing and oriented to transmit major thrust forces from the shaft to the housing and the outer race of the impeller bearing being axially slidable in the housing and oriented to transmit minor thrust forces to the housing;
• a biasing element acting between the housing and the axially slidable outer race and preloading the impeller bearing with a selected preload force maintained on the impeller bearing to maximize bearing life and concentric rotation of the shaft over all operating conditions of the pump;
• an oil control in the lubricated recess and including an oil slinger mounted on the rotatable shaft adjacent the impeller bearing and operative to centrifugally direct oil from the impeller bearing into a collector connected with an oil return passage, and a stationary oil seal including a deflector extending inward from the housing adjacent the oil slinger and operative to deflect bypassed oil into the return passage and a seal lip engaging the shaft and blocking the passage of bypassed oil along the shaft toward the fluid impeller;
• a volute connected with the impeller end of the housing for receiving pressurized water from the impeller;
• and
• a flushable water seal including a stationary water seal member having a seal surface surrounding the shaft, a rotatable water seal member mounted on the shaft and engaging the seal surface, a passage connecting the volute with a plenum, and nozzles from the plenum aimed to direct water jets against the seal surface to carry away worn particles from the seal surface and thereby increase the wear life of the water seal members.