Thermostat & Gasket for MerCruiser 3.0L 2.5L 4, 6 Cyl 140, 120HP 59078T3 18-3650

Thermostat & Gasket for MerCruiser

This thermostat and gasket set is designed for MerCruiser marine engines, ensuring optimal engine temperature regulation for 3.0L, 2.5L, 4-cylinder, and 6-cylinder models including 140HP and 120HP, with OEM cross-reference numbers 59078T3 and 18-3650.

Overview

This thermostat and gasket for MerCruiser provides reliable cooling system performance by maintaining proper operating temperature. It is essential for marine engines running 3.0L or 2.5L displacements in 4 or 6 cylinder configurations. Whether you have a 140HP or 120HP MerCruiser, this thermostat and gasket set ensures consistent engine temperature for optimal performance.

Built For Performance

• Direct replacement for MerCruiser 59078T3 and 18-3650 part numbers
• Includes both thermostat and gasket for complete installation
• Designed for saltwater and freshwater marine environments
• Constructed from corrosion-resistant materials
• Precision temperature control for engine efficiency
• Easy bolt-on installation with no modifications required

Fits These Machines

• for MerCruiser 3.0L 4-cylinder engines
• for MerCruiser 2.5L 4-cylinder engines
• for MerCruiser 4-cylinder 140HP models
• for MerCruiser 6-cylinder 120HP models
• for MerCruiser 3.0L and 2.5L sterndrive and inboard applications

On-The-Job Use

• Replacing worn or failed thermostats in MerCruiser marine engines
• Restoring proper engine operating temperature for better fuel efficiency
• Preventing overheating during extended cruising or high-RPM operation
• Maintaining consistent cooling in both fresh and saltwater conditions
• Routine maintenance during engine rebuild or cooling system overhaul

Specs At A Glance

Good To Know

Q: Does this thermostat come pre-gasketed? A: The gasket is included as a separate item; you will need to install it during assembly. Ensure the mating surfaces are clean for a proper seal.

Q: Will this work on a MerCruiser 3.0LX? A: Yes, the 3.0LX uses the same thermostat and gasket as the standard 3.0L. Confirm your engine serial number to be certain.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.