A bearing assembly for a downhole motor , comprising: a housing having a central axis , an upper end , a lower end , a through passage extending between the upper end and the lower end, a radially inner surface defining the through passage, and a radially outer surface ; a mandrel rotatably disposed within the through passage of the housing; an upper seal assembly radially positioned between the housing and the mandrel; a lower seal assembly radially positioned between the housing and the mandrel, wherein the lower seal assembly is axially positioned proximal the lower end of the housing; a thrust bearing assembly radially positioned between the housing and the mandrel, wherein the thrust bearing assembly is axially positioned between the upper seal assembly and the lower seal assembly; a lubricating fluid radially disposed between the housing and the mandrel and axially disposed between the upper seal assembly and the lower seal assembly; and a lubricant chamber positioned in a counterbore extending axially from the lower end of the housing and radially positioned between the radially inner surface of the housing and the radially outer surface of the housing, wherein a piston is disposed in the lubricant chamber and divides the lubricant chamber into an upper section axially above the piston and a lower section axially below the piston, and wherein the upper section is in fluid communication with the lubricating fluid; and wherein the lower end of the housing comprises a lower check valve radially positioned between the radially inner surface and the radially outer surface of the housing, wherein the lower check valve is in fluid communication with the lubricating fluid, wherein the lower check valve is adapted to allow at least a portion of the lubricant to exit the bearing assembly at a predetermined pressure differential. a housing having a central axis , an upper end , a lower end , a through passage extending between the upper end and the lower end, a radially inner surface defining the through passage, and a radially outer surface ; a mandrel rotatably disposed within the through passage of the housing; an upper seal assembly radially positioned between the housing and the mandrel; a lower seal assembly radially positioned between the housing and the mandrel, wherein the lower seal assembly is axially positioned proximal the lower end of the housing; a thrust bearing assembly radially positioned between the housing and the mandrel, wherein the thrust bearing assembly is axially positioned between the upper seal assembly and the lower seal assembly; a lubricating fluid radially disposed between the housing and the mandrel and axially disposed between the upper seal assembly and the lower seal assembly; and a lubricant chamber positioned in a counterbore extending axially from the lower end of the housing and radially positioned between the radially inner surface of the housing and the radially outer surface of the housing, wherein a piston is disposed in the lubricant chamber and divides the lubricant chamber into an upper section axially above the piston and a lower section axially below the piston, and wherein the upper section is in fluid communication with the lubricating fluid; and wherein the lower end of the housing comprises a lower check valve radially positioned between the radially inner surface and the radially outer surface of the housing, wherein the lower check valve is in fluid communication with the lubricating fluid, wherein the lower check valve is adapted to allow at least a portion of the lubricant to exit the bearing assembly at a predetermined pressure differential. <EOS>