Sierra 18-3650 Thermostat Kit 140° for MerCruiser GM Engines

The Sierra 18-3650 is a complete thermostat kit designed for MerCruiser 4-cylinder and 6-cylinder inline GM engines, including 2.5-liter and 3.0-liter models rated at 120, 140, and 165 horsepower. This kit opens at 140°F to maintain optimal engine operating temperature and prevent overheating in marine applications.

Kit Includes:

• 18-3550 thermostat (140°F opening temperature)
• 18-2831 top cover gasket for leak-free installation

Key Features:

• High-grade stainless steel and brass bi-metal construction for corrosion resistance
• Engineered to meet or exceed OEM specifications
• Designed to withstand harsh marine environments
• Precise temperature control for proper cooling performance

Replaces OEM Part Numbers: Mercury Marine 59078, 59078T3, 59078Q3, 59078T4, 59078A1, 59078B, 27-47590-1, 47590; GLM 13370; Mallory 9-43153

Sierra is a trusted supplier to OEM engine manufacturers and boat builders, providing quality marine parts engineered for today's high horsepower engine demands.