The engine shut-off valve system includes a housing, a gate member, a rotating lever, a locking piston assembly, and a closing piston assembly. The system is installed in fluid connection with a flow line so that air flow passes through a passageway in the housing with the gate member in the locked configuration. The air flow through the passageway stops with the gate member in the closed configuration. The gate member has an asymmetry so that the forces of the spring of the closing piston assembly and the spring of the locking piston assembly are cooperative to actuate between the closed configuration and the locked configuration, while wearing on the gate member differently so as to extend the working life of the valve system. The closing piston assembly and the locking piston assembly are separately accessible for maintenance.