A system for overriding an EMD locomotive engine protective device which includes a low water pressure sensing device in communication with the engine cooling system for shutting down the engine when low water pressure in the engine is sensed, the override system comprising a water assist pump connected to a source of water and communicating with the protective device for supplying pressurized water to the low water pressure sensing device to maintain relatively high water pressure to prevent the device from shutting down the engine; and a controller for activating the water assist pump during start up of the engine.