Thermostat & Gasket Kit – Fits Mercury Marine 8-35 HP Outboard Motors (Replaces 855676002, 8M0119207)

Thermostat & Gasket Kit – Fits Mercury Marine 8-35 HP Outboard Motors (Replaces 855676002, 8M0119207)

This thermostat and gasket kit is designed for Mercury Marine 8-35 HP 4-Stroke outboard engines (2005–present), covering most 2-cylinder and 3-cylinder models. It is also compatible with select Tohatsu and Nissan 4-Stroke models that specify a 60°C (140°F) thermostat.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 855676002, 8M0119207, 8M0139434, and 855676005; Tohatsu 3NV010300M and 3R3-01030-0; Sierra 18-43175; and Mallory 9-43175.

• Complete Kit: Includes the thermostat, thermostat cover gasket, and rubber ring seal for a full replacement.
• Precise Temperature: Regulates engine temperature at 60°C (140°F) to ensure optimal performance and prevent overheating.
• Direct Fit: Engineered as a direct-fit replacement for a hassle-free installation process.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

For Tohatsu owners, confirm your engine model/year in the table below.

Mercury Marine

Tohatsu

Technical Specifications

Package Contents

• 1 x Thermostat (855676002/8M0119207)
• 1 x Thermostat Cover Gasket (27-853702005)
• 1 x Rubber Ring Seal

Installation Guide

1. Safety First: Ensure the engine is cool and disconnect the battery cables.
2. Drain Coolant: Place a container under the engine and drain the cooling system.
3. Locate Housing: Find the thermostat housing on the engine block.
4. Remove Cover: Loosen and remove the bolts securing the thermostat housing cover.
5. Remove Old Parts: Carefully take out the old thermostat and remove any gasket or seal remnants.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover to ensure a tight seal.
7. Install New Thermostat: Position the new thermostat correctly within the housing.
8. Install New Gaskets: Place the new cover gasket and rubber ring seal in their proper positions.
9. Reassemble: Reattach the housing cover and tighten the bolts to the manufacturer's recommended torque.
10. Refill System: Refill the engine with the appropriate coolant.
11. Check for Leaks: Reconnect the battery, start the engine, and let it reach operating temperature while checking for any leaks around the housing.

Troubleshooting & FAQ

How do I confirm this fits my engine?
First, review the detailed compatibility tables for Mercury and Tohatsu models. For Mercury engines, we strongly recommend using your serial number to confirm the correct model and year range. Cross-reference your existing part number with the numbers listed in our cross-reference table to ensure a match.

What are the signs of a failing thermostat?
Common signs include engine overheating, the engine running too cool and not reaching its proper operating temperature, erratic readings on the temperature gauge, increased fuel consumption, or poor engine performance.

What is the operating temperature of this thermostat?
This thermostat is rated for and operates at 60°C (140°F). Maintaining the correct engine temperature is crucial for performance, fuel efficiency, and longevity.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.