A paint sprayer includes a motor-driven multi-stage turbine for compressing air, which subsequently flows through a venturi in a paint gun to draw in paint or some other liquid from a canister. To prevent the high-pressure air from expelling lubricant from the motor's inboard bearing, a pressure responsive annular seal axially deflects and sealingly engages an axial face of the bearing. To avoid subjecting the seal and bearing to excess air pressure and temperature created by the turbine, a bypass bleed line diverts some air to atmosphere when the paint gun is closed.