On my 1994 Yamaha 115, I have had problem with buzzer going off at ~4200 rpm. No temperature or oil problem indication on panel, have moved depthfinder pick-up to avoid cavitation, replaced both temperature sensors, replaced both thermostats, replaced water pump impeller...mechanic says engine heads aren't overheating by touching them, and installed new battery. Last time alarm went off was after a run of 25 miles at 4200. Other times has gone off on run of 2-3 miles. Alarm eventually stops when engine speed is dropped to ~2000 rpm range. It didn't do this the first 5 years that I owned motor...460 total hours on engine. Pee hole flow is strong. Gradually, even before the buzzer problem started, paint on right side of engine about 2-3 inches above the lower unit bolt line began to turn hazy white in an area about size of golf ball. After above repairs, the size of the hazy white paint has grown significantly and has appeared on left side in same approximate location. Used boat for short trip this weekend, no alarm, but now on left side, I see the hazy white discoloration coming from a cover that bolts on to the leading edge of the motor shaft just above the lower unit bolt line...looks, like water stream drainage flow pattern, but this portion of motor is always below water surface...not sure where water level reaches when at high speed or in turns. What is the engine trying to tell me with the paint discoloration and timing of alarm buzzer? What should I do to fix the problem--- I'm extremely uneasy to go out in open water out of sight of land or people?
