Apparatus and methods for determining operational health of a pump. An example method may include commencing operation of a processing device to monitor operational health of a pump for pumping a fluid at a wellsite, wherein the pump may be a reciprocating pump. During pumping operations of the pump, the processing device may receive pressure measurements of the fluid at a fluid inlet manifold and/or a fluid outlet manifold of the pump, receive position measurements of fluid displacing members of the pump, detect irregular pressure measurements based on the received pressure measurements, determine operational phase of the pump based on the received position measurements, and determine which of fluid inlet and outlet valves of the pump is leaking based on operational phase during which the irregular pressure measurements are detected.