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I purchased a boat with twin Yamaha 150, 1989. One of the motors kept having the alarm/buzzer go off for over heating. I had the motor worked on in Feb at boat yard. They replaced the impeller etc. The motor seems to be running cool but at speed the buzzer sounds and the motor stops. It will restart in a few minutes. I am open for help and suggestions. The guy who worked on my boat, does not work at the yard anymore.
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The engine shouldn't shut off the overheat warning will put it in rpm reduction it will slow down to 2000 rpm's. Check compression on engine, thermstat's and bypass valve. -
Gulfstream,
Like the boats.net mechanic says, the overheat condition should not completely shut down the motor - just put it into an rpm reduction mode and sound the alarm.
You might want to check the thermo switches - you have two, one in each head assy. They are fairly easy to remove and test. You can put them in heated water with a thermometer and monitor the two leads for closure with a voltmeter - they should close around 185 degrees f. - I have seen them close around 130 degrees, giving a false overheat condition signal to the ignition control electronics.
Get yourself a Yamaha shop manual if you are going to be doing your own maintenance - it will pay for itself. Go to www.yamahapubs.com and they will deliver to your door. Get your parts at boats.net - good service and parts at good prices.
Good luck,
Ken KComment
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Thanks for the advice!Comment
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