Thermostat Repair Service Kit – Fits Mercury Marine 4-Stroke 8-30 HP Carb/EFI Outboards (Replaces 855676002, 8M0119207, 8M0139434, 855676005)

Thermostat Repair Service Kit – Fits Mercury Marine 4-Stroke 8-30 HP Carb/EFI Outboards (Replaces 855676002, 8M0119207, 8M0139434, 855676005)Thermostat Repair Service Kit Fits Mercury Marine 4 Stroke 8 30 HP Carb EFI Outboards This comprehensive thermostat repair kit is designed for Mercury Marine 4 stroke outboards from 8 to 30 HP, specifically those with 209cc 2 or 3 cylinder Carbureted and EFI engines. It ensures your engine maintains the correct operating temperature for optimal performance and longevity. The kit is also compatible with select Tohatsu 4 stroke outboards that utilize a

Thermostat Repair Service Kit – Fits Mercury Marine 4-Stroke 8-30 HP Carb/EFI Outboards

This comprehensive thermostat repair kit is designed for Mercury Marine 4-stroke outboards from 8 to 30 HP, specifically those with 209cc 2- or 3-cylinder Carbureted and EFI engines. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.

The kit is also compatible with select Tohatsu 4-stroke outboards that utilize a thermostat with the same temperature rating. It serves as a direct replacement for multiple OEM and aftermarket part numbers, simplifying maintenance and repairs.

• Includes thermostat, cover gasket, and seals for a complete installation.
• Engineered for a precise, direct replacement fit.
• Maintains a consistent engine operating temperature of 60°C (140°F).

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.

Confirm your engine model/year in the table below.

Mercury Marine

Tohatsu

Technical Specifications

Package Contents

• 1 x Thermostat (855676002)
• 1 x Thermostat Cover Gasket (27-853702005)
• 1 x Thermostat Seals (Set)

Installation Guide

1. Disconnect the negative battery cable for safety.
2. Allow the engine to cool completely, then drain the engine coolant into a suitable container.
3. Locate the thermostat housing on the engine block.
4. Carefully remove the bolts securing the housing cover. Note their positions if they are different lengths.
5. Remove the old thermostat, gasket, and any seals. Take note of the thermostat's orientation.
6. Thoroughly clean the mating surfaces of the housing and its cover to remove any old gasket material or corrosion.
7. Install the new thermostat from the kit, ensuring it is facing the correct direction.
8. Place the new thermostat seals and cover gasket as required.
9. Reinstall the housing cover and tighten the bolts evenly to the manufacturer's recommended torque specification.
10. Refill the cooling system with the appropriate coolant.
11. Reconnect the battery cable, start the engine, and carefully check for any leaks around the housing.
12. Allow the engine to reach operating temperature to confirm the new thermostat is functioning correctly.

Troubleshooting & FAQ

How do I confirm this kit fits my engine? This kit is made for Mercury Marine 4-stroke 8-30 HP outboards with 209cc 2/3 cylinder Carb/EFI engines, plus compatible Tohatsu models. To ensure a perfect match, please compare your existing part number with those in our "Part Number Cross-Reference" table and check the "Compatible Engine Models" list.

What are the signs of a failing thermostat? Common indicators include the engine overheating or, conversely, not reaching its proper operating temperature. You may also notice erratic readings on the temperature gauge, poor fuel economy, or reduced engine performance.

What if compatibility information seems to conflict for my engine? We acknowledge that some sources may offer varied compatibility ranges. For example, part number 8M0139434 is sometimes listed for a narrow 9.9-20hp range, whereas our data supports broader 8-30hp use. For the most accurate fitment, always check the part number on your original thermostat and verify it against our cross-reference list.

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.