Yamaha T50TLR Overheat alarm.

[Sparkdr220]

Problem apparently solved. I removed the cooling water temperature sensor and cleaned it. the alarm is now occasional. I put an ohm meter on the sensor and the values did not match the manual. New sensor is on order.

[99yam40]

Problem apparently solved. I removed the cooling water temperature sensor and cleaned it. the alarm is now occasional. I put an ohm meter on the sensor and the values did not match the manual. New sensor is on order.

how did you clean it?
could the cleaning harm the sensor?
I hope you solved it but water flow indicator (TellTail) going away at Idle should not happen.

My brothers C60 had a overheat problem but at high RPM.
we dropped the lower unit and hooked a hose to the pipe heading into the power head.
pulled the stat and opened the water faucet wide open and then shot compressed air intermittently into the hose also while running the water.
there was a lot of crude that came out the stat opening.
the air and water turbulent flow flushed a lot of debris up and out of the cooling passages without pulling the head and cover.
might try that if the new sensor does not fix your problem

[Sparkdr220]

I had to scrape the crud off of the face with a small screwdriver, then used carb cleaner. It is possible I may have damaged it. I just keep flushing and vacuuming. I now have a telltail in idle and only an occasional alarm. If the sensor does not work I will drop the lower unit as you suggested.