Sierra 18-5703 Thermostat Spring for Johnson Evinrude Outboards

The Sierra 18-5703 is a replacement thermostat spring designed for the cooling systems of Johnson and Evinrude outboard engines. This precision-engineered component works within the thermostat assembly to maintain proper valve tension, ensuring the thermostat opens and closes accurately in response to coolant temperature — a critical factor in protecting your outboard from overheating or running too cold.

Key Features:

• Direct-fit replacement thermostat spring for Johnson and Evinrude outboard cooling systems
• Engineered to meet or exceed original equipment specifications
• Manufactured from durable materials built to withstand the demanding marine environment
• Helps restore proper thermostat valve function and engine temperature regulation
• Part of Sierra's extensive marine engine cooling system parts lineup

Sierra International is a trusted name in marine engine and drive components, supplying OEM-quality parts to engine manufacturers and boat builders. The 18-5703 thermostat spring is an essential small component for a complete thermostat service or rebuild on compatible Johnson and Evinrude outboards.