Yamaha 90 150 175 200 25 30 40 50 Outboard Thermostat 688-12411-11-00Yamaha Thermostat Cooling System Component 688 12411 11 00 Overview Thermostats are one of those parts I always keep an eye on, especially when an engine starts running too hot or not warming up properly. When they stick or fail, it throws off the whole cooling system. This one helps regulate engine temperature so everything runs where it should, whether youre idling or running hard. If youve been chasing temperature issues, this is usually one of the