I have twin Yamaha 2010 150hp Engines (4 Stroke) and was out running my boat today for about 3 hours. Outbound trip (90 minutes) no problems. Return trip, I was running at 3900 RPMs (my normal cruise speed) and everything was fine for most of the trip. With about 5 minutes to go I slowed the boat down to 2000 RPMs and then got an "Overheat Alarm" warning on my port engine (I didn't notice engine temperature was high or any other problems such as the engine not peeing). I immediately shut down that engine, and restarted 10 seconds later. Alarm was cleared, engine ran perfectly, and temperature was normal. Engine was peeing fine.
The only thing I can think of was that most of my trip was through very big swells and so the boat was surfing quite a bit (and although RPMs stayed constant, speed went from 25mph down to 18mph depending how I was riding the swells). I've had this before without any issues.
The engines have about 900 hours on them. They are maintained by the dealership that I bought the boat from who has Yamaha Master Technicians. Water pumps, thermostats, etc. are all replaced on a regular basis.
I ran engine for about 15 minutes after alarm went off and stayed at the correct temperature and no more alarms or other issues.
Any ideas?
The only thing I can think of was that most of my trip was through very big swells and so the boat was surfing quite a bit (and although RPMs stayed constant, speed went from 25mph down to 18mph depending how I was riding the swells). I've had this before without any issues.
The engines have about 900 hours on them. They are maintained by the dealership that I bought the boat from who has Yamaha Master Technicians. Water pumps, thermostats, etc. are all replaced on a regular basis.
I ran engine for about 15 minutes after alarm went off and stayed at the correct temperature and no more alarms or other issues.
Any ideas?