Thermostat (60°C/140°F) – Fits Suzuki 70-300 HP & Yamaha 75-250 HP 4-Stroke Outboards (Replaces 17670-90J00, 67F-12411-01-00)

Thermostat (60°C/140°F) – Fits Suzuki, Yamaha, Johnson/Evinrude & Mercury 4-Stroke Outboards

This engine thermostat is designed for a wide range of 4-stroke outboard motors, including models from Suzuki, Yamaha, Johnson/Evinrude, and Mercury/Mariner. It regulates the engine's operating temperature by opening at 60°C (140°F) to allow coolant to circulate, preventing overheating and ensuring optimal performance.

This component is a direct replacement for Suzuki part numbers 17670-90J00 / 17670-90J01, Yamaha 67F-12411-01-00 / 67F-12411-00-00, Mercury 8556761 / 5033721, and Sierra 18-3632.

• Operating Temperature: 60°C (140°F)
• Installation: Direct replacement for OEM parts
• Engine Type: Compatible with 4-Stroke outboard engines

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 Suzuki owners, You can review exploded diagrams here to verify part numbers: Suzuki Parts Diagrams & Catalog.

Confirm your engine model/year in the table below. For Yamaha owners, here’s a guide to help you identify your engine’s serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

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 Serial Number Guide.

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.

Suzuki Models

Yamaha Models

Johnson/Evinrude Models

Mercury/Mariner Models

Technical Specifications

Package Contents

• 1 x Thermostat (Replaces 17670-90J00, 67F-12411-01-00, 8556761)

Installation Guide

1. Safety First: Ensure the engine is completely cool and turned off. Disconnect the battery.
2. Locate Housing: Find the thermostat housing on the engine block. It is typically a small dome-shaped cover where the main coolant hoses connect.
3. Drain Coolant: Place a drain pan under the housing and partially drain the coolant to a level below the thermostat.
4. Remove Housing Cover: Loosen and remove the bolts holding the thermostat housing cover in place.
5. Remove Old Thermostat: Carefully lift out the old thermostat and its gasket or seal. Note its orientation.
6. Clean Surfaces: Thoroughly clean the mounting surfaces of the housing and cover, removing any old gasket material or corrosion.
7. Install New Thermostat: Place the new thermostat into the housing in the correct orientation. Ensure the new seal or gasket is properly seated.
8. Re-attach Cover: Secure the thermostat housing cover and tighten the bolts to the manufacturer's specified torque.
9. Refill Coolant: Refill the cooling system with the appropriate coolant.
10. Check for Leaks: Reconnect the battery. Start the engine and let it warm up, checking carefully for any leaks around the housing.
11. Verify Operation: Monitor the engine temperature gauge to ensure it warms up to and maintains the correct operating temperature.

Troubleshooting & FAQ

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

A: The best way is to compare your original part number to those listed in our cross-reference table. You can also review the detailed compatibility tables for your engine brand, model, and year. For specific brand guidance, use the serial number look-up links provided in the "Compatible Engine Models" section.

Q: What are the signs of a failing thermostat?

A: A thermostat can fail in two ways: stuck open or stuck closed. If it's stuck open, your engine may take a very long time to warm up or never reach its ideal operating temperature, leading to poor performance and fuel economy. If it's stuck closed, the engine will overheat quickly, which can cause severe damage. Consistently high or low readings on your temperature gauge are key indicators.

Q: What temperature does this thermostat open at?

A: This thermostat is designed to begin opening at 60°C (140°F), helping your engine maintain a stable and efficient 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.