Yamaha Outboard Thermostats

The thermostat in your Yamaha outboard does more than regulate temperature, it protects the engine from the two most common causes of internal damage: overheating and running too cold. A failed thermostat that sticks closed causes overheating within minutes. One that sticks open prevents the engine from reaching operating temperature, causing increased fuel consumption, oil dilution, and accelerated ring and cylinder wear.

Yamaha recommends thermostat replacement as a scheduled maintenance item, typically every 2-3 seasons or 300 hours. Genuine Yamaha OEM thermostats are calibrated to the precise opening temperature required for each F series engine family, not generic automotive thermostats adapted for marine use. The temperature calibration matters: a few degrees difference in opening temperature can affect engine performance and longevity.

Boat Max Online stocks OEM Yamaha thermostats for F and T series outboards across the full power range. Our catalog is organized by engine model to simplify finding the correct part for your specific Yamaha.