OEM Outboard Motor Thermostats

The thermostat is a small, inexpensive part with an outsized job: it regulates coolant flow so your outboard reaches and holds its correct operating temperature. A thermostat that fails closed causes rapid overheating and potential engine damage; one that fails open keeps the engine running too cold, increasing wear and fuel consumption. Because thermostats are a wear item that fail without warning, most manufacturers recommend replacing them on a schedule rather than waiting for symptoms.

Boat Max Online stocks genuine OEM thermostats across all three brands we carry: Honda BF, Suzuki DF, and Yamaha F series outboards. Each brand uses its own thermostat design, opening temperature, and housing gasket, so thermostats are not interchangeable between brands. This page serves as the central hub for outboard thermostats; use the brand-specific collections linked below to find the exact OEM part for your engine family.

As an authorized dealer for Honda, Suzuki, and Yamaha, every thermostat we sell is a genuine OEM component, not a generic aftermarket substitute. Free shipping on orders over $499 to the lower 48 states.

Thermostat Replacement Interval by Brand