Yamaha - Thermostat Gasket - Cooling System Seal -  F15C F20 - 6AH-12414-00-00

Overview

On smaller Yamaha four-strokes, even a minor cooling system leak can turn into a bigger issue if it’s ignored. This thermostat gasket is a simple but critical seal that keeps coolant where it belongs, helping the engine warm up properly and hold a steady operating temperature. It’s one of those parts that’s easy to overlook, but when you replace it during service, you avoid drips, air leaks, and inconsistent cooling. Clean install, proper seal, and you’re good to go.

Key Features

• OEM Precision Fit – Designed to match Yamaha thermostat housings for a proper seal without modification.
• Graphite-Coated Surface – Seals quickly under light torque and removes cleanly during future service.
• Heat & Chemical Resistant – Built to withstand engine heat, coolant exposure, and marine conditions.
• Maintains Proper Clearance – Thin profile ensures accurate thermostat operation and temperature control.

Engine & Boat Compatibility

• F15C
• F20

FAQ

Q: What does the thermostat gasket do?
A: It seals the thermostat housing to prevent coolant leaks and maintain proper engine temperature.

Q: Should I replace this gasket when changing the thermostat?
A: Yes, it’s recommended to replace it every time the thermostat is serviced.

Q: What happens if the gasket fails?
A: You may see coolant leaks, improper warm-up, or inconsistent engine temperature.

Q: Do I need sealant with this gasket?
A: No, it’s designed to seal properly without additional sealant when installed correctly.

Q: Is installation difficult?
A: It’s a simple replacement during thermostat service with basic tools.

• Engine Application
  • F15C
  • F20