My Yamaha 40 T&T unit seems to have air in it. When you run the trim motor you can hear the tone change like there is cavitation in the pump, the motor goes up and down (slowly) but will "leak" down over time. I have attempted to purge the air by raising the motor and then rotating the lift screw (not sure of the official name) on the port side of the engine which lets the motor down and is mentioned in the manual as a way to purge air from the system. The only place I can find to add fluid is the screw in the center of the pump assembly. How do you tell when it is full? And, how do you bleed the system to get the air out?
