Thermostat Repair Service Kit – Fits Mercury 75-120 HP Outboards & SportJet 90-120 HP

Thermostat Repair Service Kit – Fits Mercury 75-120 HP Outboards & SportJet 90-120 HP

This thermostat kit provides a complete repair solution, ensuring your engine maintains a consistent operating temperature of 130°F (54°C) for optimal performance and longevity. It is designed for a wide range of Mercury/Mariner outboard engines, Mercury SportJet models, and Force outboards.

This kit is a direct replacement for Mercury part numbers F664068, 859620, 828319, and F476067.

• Maintains engine temperature at 130°F (54°C).
• Includes thermostat, gasket, and seal for a complete installation.
• Designed for direct OEM replacement, ensuring a precise fit.

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.

Mercury Outboard Engines

Mercury Jet Drives

Technical Specifications

Package Contents

• 1 x Thermostat (F664068)
• 1 x Thermostat Housing Gasket (828319)
• 1 x Thermostat Seal (F664914)

Installation Guide

1. Safety First: Ensure the engine is completely cool and disconnect the battery before starting.
2. Drain Coolant: Place a drain pan under the engine and drain the cooling system.
3. Locate Housing: Find the thermostat housing on the engine block or cylinder head.
4. Remove Housing: Loosen and remove the bolts securing the thermostat housing cover.
5. Remove Old Parts: Take out the old thermostat, gasket, and seal. Note their orientation.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover to remove old gasket material and corrosion.
7. Install New Parts: Place the new thermostat, gasket, and seal in the housing, ensuring they are correctly positioned.
8. Re-secure Housing: Re-attach the housing cover and tighten the bolts to the manufacturer's specified torque.
9. Refill Coolant: Refill the cooling system with the appropriate coolant mixture.
10. Check for Leaks: Reconnect the battery, start the engine, and let it warm up. Carefully inspect for any leaks around the housing.

Troubleshooting & FAQ

Q: How do I confirm this thermostat kit fits my engine?

A: The best way is to match your engine's serial number to the ranges listed in the compatibility tables above. You can also use the cross-reference table to see if our part number matches the one you are replacing.

Q: What are the signs of a bad thermostat?

A: Common signs include the engine overheating (temperature gauge running high) or running too cold (not reaching normal operating temperature), which can lead to poor performance and fuel economy.

Q: At what temperature does this thermostat open?

A: This thermostat is designed to maintain a consistent engine temperature by opening at 130°F (54°C).

Q: OEM vs. Aftermarket?

A: 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.

Q: How fast do you ship and how much does it cost?

A: 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.

Q: What is your warranty and return policy?

A: 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.