Yamaha - Thermostat - Cooling System Temperature Control - 9.9, 15, C25, C30, C40, C55 - 6F5-12411-03-00

Overview

The Yamaha Thermostat | 6F5-12411-03-00 is one of those parts that keeps your engine running at the right temperature without you thinking about it. When it starts sticking or wearing out, you’ll notice it with overheating, running too cool, or inconsistent performance. It controls when water flows through the engine, so everything depends on it opening at the right time. If your motor isn’t holding a steady temp, this is one of the first things to check.

Key Features

• Accurate Temperature Control – Regulates water flow to maintain proper engine operating temperature.

• OEM Fit Precision – Built to Yamaha specifications for correct function and proper sealing.

• Supports Engine Efficiency – Helps maintain optimal combustion and consistent performance.

• Heat-Resistant Construction – Designed to handle continuous temperature cycles and marine use.

Engine & Boat Compatibility

• 9.9 Current
• 15 Current
• C25 Current
• C30 Current
• C40 Current
• C55 Current

FAQs

Q1: What are signs the thermostat is failing?
A: Overheating, engine running too cool, or fluctuating temperatures.

Q2: Can a bad thermostat cause overheating?
A: Yes, especially if it sticks closed and restricts water flow.

Q3: Should I replace this during routine maintenance?
A: Yes, it’s a common service item when working on the cooling system.

Q4: Does this require a gasket?
A: Yes, proper sealing is important to prevent leaks and ensure correct operation.

Q5: Is installation difficult?
A: It’s usually straightforward with basic tools and proper cleaning of surfaces.

• Supersessions
  6F5-12411-02-00, 6F5-12411-01-00
• Engine Application
  • 9.9 - Current
  • 15 - Current
  • C25 - Current
  • C30 - Current
  • C40 - Current
  • C55 - Current