F664068 Thermostat Kit for Force Mercury 90 120 150 | JLM Marine

F664068 Thermostat Kit for Force Mercury 90 120 150 | JLM Marine

This aftermarket thermostat kit is engineered to fit Force outboard engines (70, 75, 85, 90, 120, 125, 150 HP) manufactured from 1988 through 1999, as well as Mercury SportJet jet drive units (90, 95, 120 HP) across various model years. It ensures proper coolant regulation in the cylinder block, helping to maintain optimal operating temperatures and prevent overheating.

This kit directly replaces OEM part number F664068, providing a reliable solution for routine maintenance or emergency repairs on compatible Force and Mercury powerheads and jet drives.

• Designed for Force outboards and Mercury SportJet applications
• Fits cylinder block assemblies and powerheads
• Essential component for engine cooling system integrity

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.

Technical Specifications

Package Contents

Package includes the complete thermostat kit required for installation on compatible Force and Mercury engines.

Installation Guide

1. Disconnect the battery and allow the engine to cool completely before beginning work.
2. Remove the engine cowling to access the cylinder block and locate the thermostat housing.
3. Drain the coolant from the cooling system into a suitable container following manufacturer guidelines.
4. Disconnect hoses attached to the thermostat housing and remove any fasteners securing the housing cover.
5. Remove the old thermostat and gasket from the housing; clean all mating surfaces thoroughly.
6. Install the new thermostat from the kit, ensuring the valve is oriented correctly (check service manual for direction).
7. Apply a new gasket or seal as provided in the kit and reinstall the thermostat housing cover.
8. Torque fasteners to the manufacturer's specification to prevent leaks or damage.
9. Reconnect coolant hoses and refill the cooling system with the recommended coolant mixture.
10. Bleed air from the cooling system per the service manual to ensure proper circulation.
11. Reinstall the cowling, reconnect the battery, and start the engine to verify proper thermostat operation and check for leaks.
12. Monitor engine temperature during initial operation to confirm the thermostat is opening and closing correctly.

Troubleshooting & FAQ

How do I confirm this thermostat kit fits my Force or Mercury engine?
Verify your engine's HP, model year, and serial number against the compatibility table above. You can also cross-reference the OEM part number F664068 in your service manual or on the parts diagram for your specific powerhead.

What are the signs that my thermostat needs replacement?
Common symptoms include engine overheating, running too cool (poor fuel economy, sluggish performance), or coolant leaks around the thermostat housing. If the temperature gauge fluctuates abnormally, the thermostat may be sticking.

How often should I replace the thermostat on my Force or Mercury outboard?
Replace the thermostat every 2–3 years or per the manufacturer's maintenance schedule, especially if you operate in saltwater or harsh conditions. Always replace the thermostat and gasket together during major cooling system service.

Can I install this kit myself, or do I need a mechanic?
If you have basic mechanical skills and tools, you can install this kit following the service manual. However, proper torque specs, coolant bleeding, and system testing are critical—professional installation is recommended if you're unfamiliar with outboard cooling systems.

Is this an OEM or aftermarket thermostat kit?
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.