Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP (Replaces 17670-90J21, 17670-90J20)

Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP

This thermostat is designed for a precise fit in a range of Suzuki 4-stroke outboard engines from 100 HP to 300 HP. It regulates the engine temperature by opening at 50°C (122°F) to ensure optimal performance and prevent overheating.

It serves as a direct replacement for Suzuki OEM part numbers 17670-90J21 and 17670-90J20, providing a reliable aftermarket alternative.

• Engineered for direct-fit installation
• Maintains a consistent 50°C operating temperature
• Constructed from durable brass and stainless steel

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.

Technical Specifications

Package Contents

1 x Thermostat (17670-90J21)

Installation Guide

1. Safety First: Ensure the engine is completely cool and disconnected from the power source before beginning.
2. Locate Housing: Find the thermostat housing on the engine block. It is typically connected to the main coolant hoses.
3. Drain Coolant: Place a container below the housing and carefully drain a sufficient amount of coolant.
4. Remove Cover: Loosen the bolts holding the thermostat housing cover in place and gently remove it.
5. Remove Old Thermostat: Take note of the old thermostat's orientation before removing it from the housing.
6. Clean Surfaces: Thoroughly clean the mounting surfaces of both the housing and its cover, removing any old gasket material or sealant.
7. Install New Thermostat: Place the new thermostat into the housing in the correct orientation. Ensure any seals are properly seated.
8. Secure Cover: Re-attach the housing cover and tighten the bolts to the manufacturer's recommended torque. Do not overtighten.
9. Refill Coolant: Top off the cooling system with the appropriate type of coolant.
10. Check for Leaks: Reconnect the power, start the engine, and let it run for several minutes while carefully checking for any leaks around the housing.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my specific Suzuki model?
A: The best way is to match your engine's model and year against our "Compatible Engine Models" table. You can also verify by confirming your existing part number is listed as a direct replacement, such as 17670-90J21 or the superseded 17670-90J20.

Q: What are the signs of a failing thermostat?
A: Common symptoms include engine overheating, the engine temperature gauge reading unusually high or low, poor engine performance, or visible coolant leaks around the thermostat housing.

Q: What is the difference between a 50°C thermostat and others?
A: The 50°C rating indicates the temperature at which the thermostat begins to open, allowing coolant to circulate. This specific temperature is designated by the manufacturer to ensure the engine operates within its ideal temperature range for performance and longevity.

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.