Sierra 18-3540 Marine Thermostat for Yamaha Outboards 122°F

The Sierra 18-3540 is a precision-engineered marine thermostat designed as a direct replacement for Yamaha outboard engines. With a temperature rating of 122°F (50°C), this thermostat ensures your engine operates within its optimal temperature range for maximum performance and fuel efficiency.

Key Features:

• Temperature rating: 122°F (50°C) opening temperature
• Designed for Yamaha outboard motors
• Meets or exceeds OEM specifications for reliable performance
• Constructed from high-quality marine-grade materials
• Direct replacement for easy installation

OEM Cross References:

• Yamaha: 6E5-12411-30-00, 688-12411-00-00, 688-12411-01-00, 688-12411-10-00, 688-12411-11-00, 6E5-12411-10-00, 6E5-12411-20-00
• Mallory: 9-43035

A failed thermostat can cause your engine to run outside of its optimal temperature range, negatively affecting performance, efficiency, and potentially causing damage. Sierra has been manufacturing premium marine engine parts for over 50 years, earning the trust of OEM engine manufacturers and boat builders worldwide. This thermostat is engineered to withstand the harsh marine environment and provide accurate fit and function for dependable operation.