Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP (Replaces 17670-90J21, 17670-90J20)
Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP (Replaces 17670-90J21, 17670-90J20) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP (Replaces 1767...
Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP (Replaces 17670-90J21, 17670-90J20) is backordered and will ship as soon as it is back in stock.
Product Details
This replacement Thermostat (50°C) – Fits Suzuki Outboards 100-300 HP regulates engine temperature for optimal performance and efficiency. It is engineered for a direct fit on a range of Suzuki 4-stroke models from 2012 to present, including the DF100A, 115A, 140A, 150, 175, 200, 250AP, and 300AP series engines.
This thermostat serves as a direct replacement for Suzuki OEM part numbers 17670-90J21 and 17670-90J20.
- Engineered for direct-fit installation.
- Opens at a consistent 50°C (122°F) to maintain correct operating temperature.
- Constructed from a durable brass and stainless steel housing for corrosion resistance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By | Notes |
|---|---|---|---|
| Suzuki | 17670-90J20 | 17670-90J21 | Original part number. |
| Suzuki | 17670-90J21 | — | Current replacement part. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Suzuki | DF100A | 100 | 4-Stroke | 2013–Present | 17670-90J21 | Supersedes 17670-90J20 |
| Suzuki | DF115A | 115 | 4-Stroke | 2013–Present | 17670-90J21 | Supersedes 17670-90J20 |
| Suzuki | DF140A | 140 | 4-Stroke | 2013–Present | 17670-90J21 | Supersedes 17670-90J20 |
| Suzuki | DF150 | 150 | 4-Stroke | 2012–2021 | 17670-90J21 | Supersedes 17670-90J20 |
| Suzuki | DF175 | 175 | 4-Stroke | 2012–2021 | 17670-90J21 | Supersedes 17670-90J20 |
| Suzuki | DF200APL/APX/ASTL/ASTX/ATL/ATX/AZX | 200 | 4-Stroke | 2015–2020 | 17670-90J21, 17670-90J20 | Multiple trim/shaft variants |
| Suzuki | DF250AP/APX/APXX | 250 | 4-Stroke | 2012–2021 | 17670-90J21, 17670-90J20 | Multiple trim/shaft variants |
| Suzuki | DF300AP | 300 | 4-Stroke | 2012–2021 | 17670-90J21, 17670-90J20 |
Technical Specs
- Product Type
- Engine Thermostat
- Installation
- Direct Fit
- Temperature Rating
- 50°C (122°F)
- Housing Material
- Brass/Stainless Steel
- Housing Color
- Silver
- Operating Temperature
- 50°C (122°F) opening temperature
- Warranty
- Manufacturer dependent, typically 1 year
- Other Technical Attributes
- Manufactured to OEM specifications, produced in ISO9002 certified factory
What’s in the Box
- 1 x Thermostat (17670-90J21)
Installation Notes
- Ensure the engine is completely cool before beginning work. Disconnect the battery.
- Locate the thermostat housing on the engine block or cylinder head. It is typically connected to the main coolant hoses.
- Place a drain pan under the housing to catch any spilled coolant.
- Loosen the hose clamps and carefully twist the hoses off the housing nipples.
- Remove the bolts securing the thermostat housing cover. Note their placement if they are different lengths.
- Lift the cover off. The thermostat should be visible inside. Note its orientation before removing.
- Remove the old thermostat and the gasket or O-ring. Clean both mating surfaces of the housing and cover thoroughly.
- Install the new thermostat in the correct orientation. Place the new gasket or O-ring into position.
- Reinstall the housing cover and tighten the bolts to the manufacturer's specified torque in a crisscross pattern.
- Reconnect the coolant hoses and secure the clamps.
- Reconnect the battery. Refill the cooling system with the appropriate coolant.
- Start the engine and check for leaks as it warms up. Monitor the temperature gauge to ensure it operates in the normal range.
Troubleshooting & FAQ
How do I know if my thermostat has failed?
Common signs of a failed thermostat include engine overheating (stuck closed) or taking too long to reach operating temperature (stuck open). You may also notice poor engine performance or an increase in fuel consumption.
What is the operating temperature of this thermostat?
This thermostat is designed to start opening at 50°C (122°F), helping the engine warm up quickly and then maintaining a stable temperature during operation.
Will this fit my specific Suzuki model even if the part number is slightly different?
This part directly replaces Suzuki 17670-90J21 and its superseded part, 17670-90J20. Always verify compatibility by checking your engine's model, horsepower, and year against our compatibility table. If you are unsure, consult your service manual or a professional marine mechanic.
Does this thermostat come with a new gasket?
This listing is for the thermostat only. Gaskets or O-rings are typically sold separately. It is critical to use a new gasket during installation to ensure a proper seal.
Can I install this myself?
While installation can be done by a knowledgeable boat owner with the right tools, we recommend professional installation to prevent coolant leaks, overheating, and other potential engine damage.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
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