18-3669 F335068 Thermostat Kit 143° for Johnson Evinrude | JLM Marine

Thermostat Kit 143° for Johnson Evinrude Outboards – Fits 60–75 HP Models

This aftermarket thermostat kit is designed for Johnson and Evinrude outboard engines ranging from 60 HP to 75 HP, covering model years 1969–1988. The kit ensures proper engine temperature regulation for optimal performance and longevity across a wide range of applications including recreational and commercial use.

This kit directly replaces OEM part numbers 18-3669 and F335068, providing a complete solution with thermostat, gaskets, and cover components. It consolidates multiple OEM part numbers into one convenient package for easier maintenance and repair.

• Complete kit includes 143-degree thermostat, thermostat gasket, and thermostat cover gasket
• Replaces multiple Johnson/Evinrude OEM part numbers: 396987, 382385, 313416, 332108, 317226
• Fits both recreational and commercial outboard models from 1969 to 1988

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 Johnson/Evinrude owners, here's a guide to help you identify your engine's serial/model: Johnson/Evinrude Serial Number Guide.

Technical Specifications

Package Contents

This complete thermostat kit includes all components needed for installation:

• 1 × Thermostat (143-degree) – Replaces OEM # 396987 or 382385
• 1 × Thermostat Gasket – Replaces OEM # 313416
• 1 × Thermostat Cover Gasket – Replaces OEM # 332108 or 317226

Installation Guide

1. Allow the engine to cool completely before beginning work. Disconnect the battery to prevent accidental starts.
2. Locate the thermostat housing on your outboard engine (typically on the cylinder head). Consult your service manual if needed.
3. Remove the bolts securing the thermostat cover and carefully lift off the cover. Note the orientation of the old thermostat before removal.
4. Remove the old thermostat and both gaskets (thermostat gasket and cover gasket). Clean all mating surfaces thoroughly to remove old gasket material and debris.
5. Install the new thermostat gasket onto the engine block, ensuring proper alignment with the mounting holes.
6. Place the new thermostat into position with the temperature-sensing element facing toward the engine block (same orientation as the original).
7. Position the new cover gasket onto the thermostat housing. Align the cover and hand-tighten the mounting bolts.
8. Torque the cover bolts to manufacturer specifications in a crisscross pattern to ensure even seating. Avoid over-tightening to prevent gasket damage.
9. Reconnect the battery and start the engine. Allow it to reach operating temperature while monitoring for leaks around the thermostat housing.
10. Check coolant levels and top off if necessary. Verify that the engine reaches and maintains proper operating temperature.

Troubleshooting & FAQ

Q: How do I know if my thermostat needs replacement?
A: Common signs include engine overheating, failure to reach normal operating temperature, temperature gauge fluctuations, or coolant leaks around the thermostat housing. If your engine runs too hot or too cold, the thermostat is often the culprit.

Q: How do I confirm this kit fits my specific Johnson or Evinrude engine?
A: Cross-reference your engine's HP rating and year with the compatibility table above. You can also verify by matching your current thermostat's OEM part number (396987, 382385, or kit number 18-3669/F335068) with this listing.

Q: What is the difference between a 143-degree and other temperature thermostats?
A: The 143°F thermostat is the OEM-specified temperature for these Johnson/Evinrude models. Using the correct temperature rating ensures proper engine cooling, performance, and longevity. Always match the original thermostat temperature specification.

Q: How often should I replace my outboard thermostat?
A: Thermostats should be inspected annually and replaced every 2–3 years or as needed based on performance. If you notice temperature regulation issues or if the thermostat fails to open/close properly during testing, replace it immediately.

Q: Can I test the thermostat before installation?
A: Yes. Place the thermostat in a pot of water with a thermometer and slowly heat the water. The thermostat should begin to open at approximately 143°F and be fully open within 10–15 degrees above that temperature.

Q: Is this an OEM or aftermarket part?
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.