Yamaha - Thermostat Cover - Cooling System Housing - 6H4-12413-00-1S

Overview

I’ve seen cooling issues come down to something as simple as a bad seal around the thermostat housing. This cover keeps everything contained and flowing the way it should once the engine warms up. If it’s warped, cracked, or not sealing right, you can end up chasing temperature problems that don’t make sense at first. It’s a straightforward part, but it plays a key role in keeping the cooling system tight and reliable.

Key Features

• Thermostat Housing Protection – Encloses the thermostat to maintain proper coolant flow and system pressure.
• Secure Sealing Surface – Helps prevent leaks and ensures consistent cooling system operation.
• OEM Fitment Design – Built to Yamaha specifications for proper alignment and installation.
• Heat-Resistant Construction – Designed to handle constant temperature changes during engine operation.
• Cooling System Support – Works with the thermostat to regulate engine temperature effectively.

Engine & Boat Compatibility

Designed for Yamaha outboards equipped with compatible thermostat and cooling system assemblies. Commonly used across small to mid-size engines on fishing boats, skiffs, and recreational vessels. Always verify compatibility with your specific engine before installation.

FAQ

Q: What are signs this cover needs to be replaced?
A: Coolant leaks, corrosion, or warping around the sealing surface are common signs.

Q: Can this cause overheating issues?
A: Yes, if it doesn’t seal properly, it can disrupt coolant flow and affect temperature control.

Q: Should I replace the gasket when installing this?
A: Always—using a new gasket ensures a proper seal and avoids leaks.

Q: Is installation complicated?
A: Not usually, but proper torque and sealing are important to avoid future issues.

Q: Does saltwater exposure affect this part?
A: Over time, yes—corrosion can develop, especially if the cooling system isn’t flushed regularly.

• Supersessions
  6H4-12413-00-9M