Abstract: A protector for liquid-filled, submersible electric motors is provided. The protector has a resiliently deformable, liquid-filled reservoir which is attached to the housing of the electric motor. The motor liquid and the reservoir liquid are communicated at the attachment. The protector compensates for volume changes of the motor liquid, due to heating or cooling thereof, by expansion or contraction of the deformable reservoir. By compensating for motor liquid volume changes, internal motor parts are protected and isolated from external fluids.