Yamaha 200 False Alarm?

I have a 1996 Yamaha 200 Saltwater Series (since new), 580 hours, professionally and regularly maintained. Recently, the overheating alarm has come on every time I run it up over 4000 rpm. There is a good stream of water coming out and it is cool. My mechanic is scratching his head. Is it possible the sensor and/or the alarm are the problem?<br /><br />Thanks. John

Re: Yamaha 200 False Alarm?

A professional and trained Yamaha mechanic scratching his head on a 9 year old motor with an overheating problem???? Now if it was a "carport cowboy" or a "I can fix anything" type of "mechanic" that is understandable.<br /><br />Has the motor been run using an infrared temp gun to see the exact temperature that each cylinder head is operating at?<br /><br />Were the the water pump and thermostats replaced? If so, was a complete factory water pump kit installed, or just an impeller?<br /><br /> What did the mechanic find when he serviced the poppet valve assembly? Did he install the new style valve?<br /><br />Have the temp senders been removed and tested in a pan of water?<br /><br />Are there any tranducers, or thru-hull fittings within 17" of the motor centerline that may affect clean water flow to the gearcase water inlets?<br /><br />Have the cylinder heads been taken apart and the passageways cleaned out if the motor was used in saltwater?

Re: Yamaha 200 False Alarm?

what seahorse says. <br /> and is he certain its overheat?<br /> what visual indicators are lit?

Re: Yamaha 200 False Alarm?

I see.....Will have a discussion with the mechanic and had better start going about things methodically. But are sensors and alarms known to fail over time? (it's the red temperature indicator which lights up)

Re: Yamaha 200 False Alarm?

My 1997 had similar problem.<br /><br />Did all the above [under the mechanic's shade tree who used hand rather than IR temp gun]: new water pump assembly, new therms, tested sencors, cleaned poppet. Still overheated when run over 4000 for ten min. Alarm audible, red indicator, and de-powered [limp home mode]. Run all day at 3600. <br /><br />Applied green poltice $$. Took it to dealer who took off the head and small obstruction next to stb senser. No damage.