Thermostat Kit – Fits Yamaha F115/F130 & Mercury 8–50HP (Replaces 6EK-12411-00-00, 855676)
Thermostat Kit – Fits Yamaha F115/F130 & Mercury 8–50HP (Replaces 6EK-12411-00-00, 855676) is backordered and will ship as soon as it is back in stock.
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Thermostat Kit – Fits Yamaha F115/F130 & Mercury 8–50HP (Replac...
Thermostat Kit – Fits Yamaha F115/F130 & Mercury 8–50HP (Replaces 6EK-12411-00-00, 855676) is backordered and will ship as soon as it is back in stock.
Product Details
This Thermostat Kit – Fits Yamaha F115/F130 & Mercury 8–50HP (Replaces 6EK-12411-00-00, 855676) is an essential component for maintaining correct engine operating temperature. It is designed for a range of 4-stroke outboards, including Yamaha F115, LF115, and VF115 models (2014–2022), F130 models (2021 and up), and various Mercury 8–50HP 4-stroke engines.
It serves as a direct replacement for Yamaha part 6EK-12411-00-00; Mercury parts 855676, 825212, and 824853; and Sierra Marine equivalents 18-3639 and 18-3642.
- Engineered for direct-replacement installation.
- Constructed from corrosion-resistant metals for marine environments.
- Includes the required thermostat seal for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6EK-12411-00-00 |
| Mercury | 855676 |
| Mercury | 825212 |
| Mercury | 824853 |
| Sierra Marine | 18-3639 |
| Sierra Marine | 18-3642 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha outboards, this thermostat fits select F115, F130, and related 4-stroke models from 2014 and later. Refer to the table for specific model codes and years.
For Mercury outboards, this part is compatible with a range of 8–50HP 4-stroke engines. Due to limited source data, it is critical to confirm your engine's required part number before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | F115JB | 115 | 4-Stroke | 2014–2016 | 6EK-12411-00-00 | |
| Yamaha | F115LB | 115 | 4-Stroke | 2014–2016 | 6EK-12411-00-00 | |
| Yamaha | F115XB | 115 | 4-Stroke | 2014–2016 | 6EK-12411-00-00 | |
| Yamaha | LF115XB | 115 | 4-Stroke | 2014–2016 | 6EK-12411-00-00 | |
| Yamaha | VF115LA | 115 | 4-Stroke | 2015 | 6EK-12411-00-00 | |
| Yamaha | F115 | 115 | 4-Stroke | 2006–2023 | 6EK-12411-00-00 | Also fits VF115/LF115 variants |
| Yamaha | F130/LF130 | 130 | 4-Stroke | 2021 and up | 6EK-12411-00-00 | |
| Mercury | Various Models | 8–50 | 4-Stroke | 855676, 825212, 824853 |
Technical Specs
- Product Type
- Marine Outboard Engine Thermostat
- Installation
- Direct replacement
- Thermostat Rating
- 143°F / 60°C
- Housing Material
- Corrosion-resistant metal
- Operating Temperature
- 143°F / 60°C opening temperature
- Other Technical Attributes
- Includes thermostat seal
What’s in the Box
- 1 x Thermostat (6EK-12411-00-00)
- 1 x Thermostat Seal (6EK-12412-00-00)
Installation Notes
- Ensure the engine is off and cool. Disconnect the battery for safety.
- Drain the engine coolant to a level below the thermostat housing.
- Locate and remove the bolts securing the thermostat housing cover.
- Carefully lift away the cover and remove the old thermostat and its seal or gasket.
- Thoroughly clean the mating surfaces of the housing and cover to ensure a proper seal.
- Install the new thermostat and seal, ensuring they are correctly oriented as per your service manual.
- Re-secure the housing cover, tightening bolts to the manufacturer's specified torque in a crisscross pattern.
- Refill the cooling system with the recommended coolant.
- Reconnect the battery, start the engine, and carefully check for any leaks around the housing. Allow the engine to reach operating temperature to confirm function.
Troubleshooting & FAQ
How do I confirm this thermostat fits my specific engine?
The surest way is to cross-reference the part number. Check your engine's service manual or existing thermostat for a part number (e.g., 6EK-12411-00-00, 855676). If it matches our listed equivalents, it will fit. For Mercury models, compatibility is broad but not exhaustively documented, so part number verification is crucial.
What are the signs of a bad or failing thermostat?
Common symptoms include engine overheating (stuck closed) or taking too long to reach operating temperature (stuck open). You might notice alarms, inconsistent temperature gauge readings, or reduced engine performance.
Can I install this thermostat myself?
Yes, this is a common DIY task for those with basic mechanical skills. However, ensuring proper sealing and torque is critical to prevent leaks. If you are not comfortable with the process, we recommend professional installation.
What is the opening temperature of this thermostat?
This thermostat is rated to begin opening at 143°F (60°C), which is the standard specification for the listed engine models to ensure optimal performance and efficiency.
How often should a marine thermostat be replaced?
Preventive replacement is recommended every 200–300 hours or every 2–3 years, especially if operating in saltwater. A stuck thermostat can cause severe engine damage, making proactive replacement a wise investment.
My engine is a Mercury 40HP 4-stroke. Will this part fit?
It is likely, as this thermostat covers many models in the 8-50HP range. However, Mercury used several different parts over the years. Please verify that your engine requires one of the listed OEM numbers (855676, 825212, 824853) before purchasing.
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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