Yamaha - Thermostat - Cooling System - 6E5-12411-02-00

Overview

On these smaller Yamaha outboards, the thermostat plays a big role in how the engine warms up and runs. When it’s working right, the motor reaches temperature and stays there without running too cold or too hot. I’ve seen engines run rough or even overheat just because the thermostat stuck open or closed. Swapping it out is a simple fix that helps keep everything running steady.

Key Features

• Controlled Engine Temperature – Regulates water flow to maintain proper operating temperature.
• Reliable Opening Response – Designed to open and close consistently based on engine heat.
• Corrosion-Resistant Build – Built to handle constant exposure to water and marine conditions.
• Direct OEM Fitment – Matches original specifications for proper installation and function.

Engine & Boat Compatibility

Designed for Yamaha 2-stroke outboard engines using thermostat-controlled cooling systems. Commonly used on small horsepower motors found on skiffs, dinghies, and lightweight fishing boats.

FAQ

Q: What are signs of a bad thermostat?
A: Overheating, engine running too cold, or inconsistent temperature are common signs.

Q: Can a stuck thermostat affect performance?
A: Yes, it can cause rough running or reduced efficiency if the engine isn’t at the right temperature.

Q: Is this something I should replace regularly?
A: It’s a good idea to check it during cooling system service and replace if there’s any doubt.

Q: Does saltwater use impact the thermostat?
A: Over time, yes—corrosion and buildup can affect how it opens and closes.

Q: Is installation difficult?
A: Not at all—just make sure surfaces are clean and everything is seated properly.

• Supersessions
  6E5-12411-01-00, 6E5-12411-00-00