Thermostat 50°C/122°F – Fits Yamaha 4-Stroke 2.5–70 HP (Replaces 6G8-12411-00, 69M-12411-00/01)
Thermostat 50°C/122°F – Fits Yamaha 4-Stroke 2.5–70 HP (Replaces 6G8-12411-00, 69M-12411-00/01) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Thermostat 50°C/122°F – Fits Yamaha 4-Stroke 2.5–70 HP (Replaces 6G...
Thermostat 50°C/122°F – Fits Yamaha 4-Stroke 2.5–70 HP (Replaces 6G8-12411-00, 69M-12411-00/01) is backordered and will ship as soon as it is back in stock.
Product Details
This is a replacement Thermostat 50°C/122°F – Fits Yamaha 4-Stroke 2.5–70 HP Outboards, designed to regulate engine temperature for optimal performance and longevity. It is engineered for a broad range of Yamaha 4-Stroke marine engines from 2.5 HP to 70 HP, covering models from 1987 to the present, including popular series like F2.5, F9.9, F15, and F20.
This part serves as a direct interchange for Yamaha part numbers 6G8-12411-00, 69M-12411-00, 69M-12411-01, 6AH-12411-00, and Sierra 18-3624.
- Installation: Designed for OEM direct replacement.
- Operating Temperature: Opens at 50°C (122°F) to maintain correct engine temperature.
- Materials: Constructed from a corrosion-resistant alloy for durability in marine environments.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 6G8-12411-00 | Primary OEM part number for many models. |
| Yamaha | 69M-12411-00 | Superseded by 69M-12411-01. |
| Yamaha | 69M-12411-01 | OEM replacement. |
| Yamaha | 6AH-12411-00 | OEM replacement. |
| Sierra | 18-3624 | Aftermarket cross-reference. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This thermostat is compatible with a wide array of Yamaha 4-stroke outboard engines. Verify your model and year against the list to ensure proper fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | F2.5MSH-0405, F2.5MSH-0406, F2.5MSH-0407, F2.5MSH0608, F2.5MSHD-2005 | 2.5 | 4-Stroke | 2003–2004 | 69M-12411-01 | Superseded 69M-12411-00 |
| Yamaha | F2.5MSHB | 2.5 | 4-Stroke | 2003 | 69M-12411-01 | Superseded 69M-12411-00 |
| Yamaha | F2.5MSHC | 2.5 | 4-Stroke | 2004 | 69M-12411-01 | Superseded 69M-12411-00 |
| Yamaha | F9.9H (6CA) | 9.9 | 4-Stroke | 2009 and newer | 6G8-12411-00 | |
| Yamaha | F15C (6AG) | 15 | 4-Stroke | 2007 and newer | 6G8-12411-00 | |
| Yamaha | F20B (6AH) | 20 | 4-Stroke | 2007 and newer | 6G8-12411-00 | |
| Yamaha | Various 4-stroke models | 9.9–70 | 4-Stroke | 1987–present | 6G8-12411-00 | General compatibility |
Technical Specs
- Product Type
- Outboard Engine Thermostat
- Installation
- OEM Direct Replacement
- Opening Temperature
- 50°C (122°F)
- Housing Material
- Corrosion-resistant alloy
- Technical Attributes
- Precision-engineered sealing components
What’s in the Box
- 1 x Outboard Thermostat (50°C / 122°F)
- 1 x Gasket (Replaces 62Y-12414-00)
- 1 x O-ring
Installation Notes
- Ensure the engine is cool and disconnect the battery for safety.
- Locate the thermostat housing on the engine block. Place a container underneath to catch any residual coolant.
- Carefully remove the bolts securing the thermostat cover. Note their positions if they are different lengths.
- Remove the old thermostat and gasket. Take note of the thermostat's orientation.
- Clean both the housing and cover surfaces thoroughly, removing all old gasket material and corrosion.
- Install the new thermostat in the correct orientation, followed by the new gasket/o-ring.
- Securely refasten the thermostat cover, tightening bolts to the manufacturer's specified torque in a crisscross pattern.
- Reconnect the battery, start the engine, and check for any leaks around the housing as the engine warms up.
Troubleshooting & FAQ
How do I know if my thermostat needs replacing?
Common signs of a faulty thermostat include the engine overheating at low speeds, or conversely, the engine failing to reach its normal operating temperature after sufficient warmup time. An inaccurate temperature gauge reading can also be an indicator.
Will this fit my specific Yamaha F-series outboard?
This thermostat is designed for a wide range of Yamaha 4-stroke models. Please consult the "Engine & Model Compatibility" table and cross-reference your engine's model and year. For absolute certainty, check the part number stamped on your original thermostat.
What is the difference between 6G8-12411-00 and 69M-12411-01?
These part numbers are often interchangeable, with 69M-12411-01 typically superseding the older 69M-12411-00. Both are functionally equivalent to 6G8-12411-00 in many applications. Always verify the correct part number for your specific engine serial number if in doubt.
Are gaskets or O-rings included with the thermostat?
This kit includes one thermostat, one gasket, and one o-ring. However, it is always a good practice to verify the contents upon arrival and have a spare gasket on hand, as a perfect seal is critical for preventing leaks.
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.
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