200 yamaha overheat horn

[grsmnkyal]

I have twin 1990 200hp yamaha's on my boat. Yesterday, when throttling up to get on plane, my port motor overheat alarm sounded, and the light was flashing. When I got back to the dock, I cleaned out the poppet, and the tattle tale line. The motor has a strong stream at idle. Today, I took the boat out again, but the same thing happened. My Temp gauge was not in the red, and the stream of water coming out was strong. Any ideas? These have always been good motors, this is the first time there has been any trouble. Thanks for any help. Al

 

[JUSTINTIME]

Re: 200 yamaha overheat horn

sounds like a bad sensor
u need to get a temp gun or those temp sticks to find out the problem

 

[rodbolt]

Re: 200 yamaha overheat horn

bad sensor or scale inside the block and water jackets, are you positive the flashing indictor was temp and not oil ? could be a bad T-stat as well. a temp gun or melt stick will aide in testing what is going on. the 90 200 yamaha should run around 145 degrees or so.

 

[grsmnkyal]

Re: 200 yamaha overheat horn

I'm pretty sure it was overheat, horn stopped going off when the temp gauge dropped a little bit. Then I was able to restart the motor and idle back home.

 

[rodbolt]

Re: 200 yamaha overheat horn

pretty sure aint sure. a clogged remote oil tank filter will give similar alarms. pay careful attention to the visual indicators on the tach. thats why they are there. the horn is the sme for all alarms.

 

[Ray Neudecker]

Re: 200 yamaha overheat horn

Engines of that age,much more so when run in salt wate, are due for a complete going through of the cooling system from the water pump, poppet valve and heads.