A hydraulic system for a marine engine has a fluid reservoir, a bi-directional pump, a valve assembly, and a hydraulic actuator. The valve assembly includes: first and fourth apertures fluidly communicating with the pump, second and third apertures fluidly communicating with the actuator, and a fifth aperture fluidly communicating with the fluid reservoir. Operating the pump to supply hydraulic fluid to the first aperture causes hydraulic fluid to flow from the pump to the actuator and from the actuator to the fluid reservoir, and causes the actuator to move in a first actuator direction. Operating the pump to supply hydraulic fluid to the fourth aperture causes hydraulic fluid to flow from the pump to the actuator and from the actuator to the pump, and causes the actuator to move in a second actuator direction opposite the first actuator direction.