Mercury 35-40-50-60HP EFI 4-Stroke Thermostat 8M0117413 Outboard Engine 18-3640

Thermostat for Mercury 35-40-50-60HP EFI 4-Stroke Outboard Engines

This thermostat for Mercury outboard engines maintains proper cooling system temperature and cross-references OEM part numbers 8M0117413 and 18-3640.

Overview

This thermostat is a direct replacement cooling component for Mercury 35HP, 40HP, 50HP, and 60HP EFI 4-stroke outboard engines. It controls coolant flow to help the engine run at the correct temperature in both fresh and salt water. This thermostat is built for Mercury outboard owners and marine technicians performing cooling system service.

Built For Performance

• Precision-engineered opening temperature matched to Mercury 4-stroke outboards
• Corrosion-resistant materials for harsh marine environments
• OE-style body and sealing surface for dependable coolant flow
• Direct replacement fit for select Mercury 35-60HP EFI 4-stroke models
• Rigorous quality checks help ensure consistent performance

Fits These Machines

• for Mercury 35HP EFI 4-Stroke outboard
• for Mercury 40HP EFI 4-Stroke outboard
• for Mercury 50HP EFI 4-Stroke outboard
• for Mercury 60HP EFI 4-Stroke outboard

On-The-Job Use

• Replacing a failed thermostat during an outboard cooling system overhaul
• Maintaining proper operating temperature for Mercury EFI 4-stroke engines
• Supporting routine annual maintenance in saltwater and freshwater boating
• Helping prevent overheating and cold-engine running issues

Specs At A Glance

Good To Know

Q: Why replace a thermostat on a Mercury outboard? A: A worn thermostat can cause overheating or slow warm-up, and replacing it restores correct engine temperature and cooling efficiency.

Q: Will this thermostat fit a Mercury 60HP EFI 4-stroke? A: It is designed for select Mercury 35-60HP EFI 4-stroke outboards with cross-reference 8M0117413 or 18-3640, so verify your engine serial number before ordering.

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