Thermostat Repair Service Kit for Mercury 75 90 120 HP Outboard Motors and Mercury SportJet 90 95 120 HP Jet Drives F664068

Thermostat Repair Kit – Fits Mercury/Mariner 75-120 HP & SportJet 90-95-120 HP

This thermostat repair kit is designed for a range of Mercury/Mariner outboards (75-120 HP) from approximately 1990-1999 and Mercury SportJet models (90-120 HP) from 1993-1997. It provides a reliable solution for maintaining optimal engine operating temperature.

This kit is a direct replacement for Mercury part numbers F664068, 859620, 828319, and F476067, as well as other aftermarket equivalents.

• Includes the thermostat, housing gasket, and seal for a complete installation.
• Engineered as a direct OEM-quality replacement for straightforward fitment.
• Maintains a consistent engine temperature of 130°F (54°C).

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 off and cool. Disconnect the battery.
2. Drain Coolant: Partially drain the engine coolant below the level of the thermostat housing.
3. Locate Housing: Find the thermostat housing on the engine block or cylinder head.
4. Remove Housing: Unscrew the bolts holding the thermostat housing cover. Note their positions if they are different lengths.
5. Remove Old Parts: Take out the old thermostat, gasket, and seal. Remember the thermostat's orientation.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and cover, removing all old gasket material.
7. Install New Parts: Place the new thermostat, seal, and gasket in position, ensuring correct orientation.
8. Reassemble: Re-attach the housing cover and tighten the bolts to the manufacturer's recommended torque.
9. Refill Coolant: Top off the engine with the appropriate coolant.
10. Check for Leaks: Reconnect the battery, start the engine, and let it reach operating temperature. Carefully check for any leaks around the housing.

Troubleshooting & FAQ

Q: How do I confirm this 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 verify by cross-referencing your existing part number with those listed in the "Part Number Cross-Reference" section. Using our linked Mercury Serial Number Guide can also help you confirm your model and year.

Q: What are the signs of a faulty thermostat?

A: Common symptoms include the engine overheating (running too hot) or taking too long to reach its proper operating temperature (running too cold). An erratic temperature gauge reading can also indicate a problem.

Q: What temperature does this thermostat operate at?

A: This thermostat is rated to open at 130°F (54°C) to regulate engine temperature.

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.