Thermostat (140°F/60°C) – Fits Johnson/Evinrude 60-300 HP V4/V6/V8 (Replaces 0329766, 0394409)

Thermostat (140°F/60°C) – Fits Johnson/Evinrude 60-300 HP V4/V6/V8

This aftermarket thermostat is engineered to fit a wide range of Johnson and Evinrude outboard engines, including 3-cylinder, V4, V6, and V8 models manufactured between 1985 and 1993. It operates at a factory-rated 140°F (60°C) to ensure your engine maintains optimal temperature for performance and longevity.

Designed as a direct replacement, this part meets or exceeds original equipment specifications for reliable function. It is a substitute for Johnson/Evinrude OEM parts 0329766, 0394409, 0434137, and 0765580, along with several other aftermarket equivalents.

• Operating Temperature: Opens at 143°F (62°C)
• Installation Method: Direct replacement
• Primary Materials: Brass and metal construction

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

1 x Thermostat (Replaces 0329766, 0394409, 0434137, 0765580)

Installation Guide

1. Disconnect Power: Ensure the engine is off and disconnect the battery terminals to prevent accidental starting. Drain the engine's cooling system into a suitable container.
2. Locate Housing: Find the thermostat housing on the engine block or cylinder head. It is typically a metal cover with one or more coolant hoses attached.
3. Remove Housing: Loosen the hose clamps and carefully detach the coolant hoses. Remove the bolts securing the thermostat housing cover.
4. Extract Old Thermostat: Lift the cover away and note the orientation of the old thermostat before removing it from the engine.
5. Clean Surfaces: Thoroughly clean any old gasket material or sealant from both the housing cover and the engine's mounting surface.
6. Install New Thermostat: Insert the new thermostat into the engine, ensuring it is oriented correctly (the spring-side usually faces the engine).
7. Secure Housing: Place the new gasket (if applicable) and reinstall the housing cover. Tighten the bolts to the manufacturer's recommended torque specification.
8. Reconnect Hoses: Reattach the coolant hoses and tighten the clamps securely.
9. Refill Coolant: Refill the cooling system with the appropriate type and amount of coolant.
10. Check for Leaks: Reconnect the battery. Start the engine and let it run for several minutes, carefully checking for any coolant leaks around the thermostat housing.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my engine?
A: The best way is to check your engine's model, year, and horsepower against the compatibility table above. You can also verify by comparing your existing part number to those listed in our cross-reference table.

Q: What is the operating temperature of this thermostat?
A: This thermostat is rated for 140°F (60°C). It is designed to begin opening at approximately 143°F (62°C) to regulate the engine's operating temperature.

Q: How often should I replace my outboard's thermostat?
A: Thermostats are a critical maintenance item. It is recommended to inspect and potentially replace them every 1-2 seasons, especially if you operate in saltwater. Replace it immediately if you notice signs of overheating or if the engine is not reaching its proper operating 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.