Stop drips before they start with the Yamaha Thermostat Gasket 6AH-12414-00-00, sized for F15C and F20 four-strokes. This thin but tough seal slips between the thermostat cover and cylinder head, locking in coolant so your motor warms quickly and stays at its sweet-spot temperature run after run.

Stamped from a heat-resistant fiber-graphite composite, the gasket’s smooth graphite face won’t stick to aluminum surfaces, making the next service just as simple as the first. The oval water passage and twin 6 mm bolt eyes are laser-cut for a factory-tight fit, so there’s no trimming or messy RTV guesswork.

Why it belongs in your spares box

• Exact OEM geometry: bolt holes and coolant port line up perfectly with F15C/F20 housings.

• Graphite coating: seals first time under light torque and peels off clean at replacement time.

• Heat & chemical toughness: holds shape at 250 °F and shrugs off glycol, salt, and corrosion inhibitors.

• Paper-thin profile: maintains precise thermostat clearance for consistent opening temps.

Swap this gasket at every thermostat change and keep coolant where it belongs—inside the block, not dripping into the cowling.