Yamaha - Thermostat Seal - Cooling System - 6E5-12412-00-00

Overview

This is one of those small seals that can cause bigger cooling issues if it’s not doing its job right. Around the thermostat, everything depends on a tight seal to keep water flowing where it should. I’ve seen engines run hotter than they should just because this seal was worn or flattened out. It’s a simple replacement, but it helps keep the cooling system working the way Yamaha designed it.

Key Features

• Secure Thermostat Sealing – Creates a tight seal to keep water flowing properly through the cooling system.
• Heat-Resistant Material – Built to handle constant temperature changes without breaking down.
• Prevents Cooling Leaks – Helps maintain proper pressure and eliminates unwanted water loss.
• OEM Fit Design – Matches original specifications for proper placement and easy installation.

Engine & Boat Compatibility

Designed for Yamaha 2-stroke outboard engines with standard thermostat-controlled cooling systems. Commonly used on smaller horsepower motors found on skiffs, jon boats, and general-purpose fishing boats.

FAQ

Q: What happens if the thermostat seal fails?
A: You can get cooling leaks or improper water flow, which may lead to overheating.

Q: Should I replace this when changing the thermostat?
A: Yes, it’s always a good idea to replace the seal at the same time.

Q: Can a bad seal affect engine temperature?
A: Definitely—if it doesn’t seal properly, the thermostat won’t regulate temperature correctly.

Q: Is installation difficult?
A: Not at all—just make sure the surface is clean and the seal is seated properly.

Q: Does saltwater use wear this part out faster?
A: Yes, salt and heat cycles can cause it to harden or lose its sealing ability over time.