Thermostat Kit – Fits Yamaha 2-Stroke 75-250 HP (Replaces 6E5-12411-30-00, 688-12411, 688-12414)
Thermostat Kit – Fits Yamaha 2-Stroke 75-250 HP (Replaces 6E5-12411-30-00, 688-12411, 688-12414) 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 Kit – Fits Yamaha 2-Stroke 75-250 HP (Replaces 6E5-12411...
Thermostat Kit – Fits Yamaha 2-Stroke 75-250 HP (Replaces 6E5-12411-30-00, 688-12411, 688-12414) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Thermostat Kit – Fits Yamaha 2-Stroke 75-250 HP is designed for a wide range of Yamaha 2-stroke outboard motors from 75 HP to 250 HP, including popular Z150, Z175, Z200, 115TLR, 150TXR, and 200TXR models manufactured between 2003 and 2014.
It serves as a direct interchange for Yamaha part numbers 6E5-12411-30-00, 688-12411, Sierra 18-3540, and Mallory 9-43035, among other equivalents.
- Designed for direct, hassle-free installation.
- Built with corrosion-resistant materials for the marine environment.
- Includes thermostat, gasket, and seal for a complete replacement.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6E5-12411-30-00 |
| Yamaha | 6E5-12411-20-00 |
| Yamaha | 6E5-12411-10-00 |
| Yamaha | 688-12411-11-00 |
| Yamaha | 688-12411-10-00 |
| Yamaha | 688-12411-01-00 |
| Yamaha | 688-12411-00-00 |
| Sierra | 18-3540 |
| Mallory | 9-43035 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This thermostat kit fits a broad range of Yamaha 2-stroke outboards. Verify your specific model is listed.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 115TLR | 115 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Includes 115TLRB (2003), 115TLRC (2004), 115TLRD (2005) |
| Yamaha | 115TXR | 115 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes 115TXRB (2003), 115TXRC (2004), 115TXRD (2005) |
| Yamaha | 130TLR/TXR | 130 | 2-Stroke | 2003–2004 | 6E5-12411-30-00 | Includes 130TLRB/C, 130TXRB/C models |
| Yamaha | 150TXR | 150 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Includes 150TXRB (2003), 150TXRC (2004), 150TXRD (2005) |
| Yamaha | V150TLR | 150 | 2-Stroke | 2003–2008 | 6E5-12411-30-00 | Includes V150TLRB/C/D variants |
| Yamaha | VZ150TLR | 150 | 2-Stroke | 2003–2014 | 6E5-12411-30-00 | Fits through VZ150TLR_0112 variants |
| Yamaha | Z150TLR/TXR | 150 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes Z150TLRB, Z150TXRB/C/D models |
| Yamaha | VZ175TLR | 175 | 2-Stroke | 2003–2012 | 6E5-12411-30-00 | Includes models through VZ175TLR_0112 |
| Yamaha | Z175TXR | 175 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes Z175TXRB/C/D models |
| Yamaha | LZ200TXR | 200 | 2-Stroke | 2003–2012 | 6E5-12411-30-00 | Includes models through LZ200TXR_0112 |
| Yamaha | Z200TLR | 200 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes Z200TLRD (2005) |
| Yamaha | Z200TXR | 200 | 2-Stroke | 2003–2012 | 6E5-12411-30-00 | Includes models through Z200TXR_0112 |
| Yamaha | SX200TXR | 200 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes SX200TXRB/C/D models |
| Yamaha | VX200TLR | 200 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes VX200TLRB/C/D models |
| Yamaha | LX225TXR | 225 | 2-Stroke | 2003 | 6E5-12411-30-00 | Model LX225TXRB |
| Yamaha | SX225TXR/TUR | 225 | 2-Stroke | 2003 | 6E5-12411-30-00 | Models SX225TXRB, SX225TURB |
| Yamaha | VX225TLR | 225 | 2-Stroke | 2003–2004 | 6E5-12411-30-00 | Includes VX225TLRB/C models |
| Yamaha | LX250TXR | 250 | 2-Stroke | 2003 | 6E5-12411-30-00 | Model LX250TXRB |
| Yamaha | SX250TXR/TUR | 250 | 2-Stroke | 2003 | 6E5-12411-30-00 | Models SX250TXRB, SX250TURB |
| Yamaha | VX250TLR | 250 | 2-Stroke | 2003–2004 | 6E5-12411-30-00 | Includes VX250TLRB/C models |
| Yamaha | 9.9MSH | 9.9 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Includes 9.9MSHB/C/D variants |
| Yamaha | 15MSH | 15 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Includes 15MSHB/C/D variants |
| Yamaha | 25MSH/MLH/ESH/ELH/ESR/ELR | 25 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Multiple variant models |
| Yamaha | 40TLR | 40 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Includes 40TLRB/C/D variants |
| Yamaha | 50TLR | 50 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Includes 50TLRB/C/D variants |
Technical Specs
- Product Type
- Thermostat Kit
- Installation
- Direct Replacement
- Temperature Rating
- 50°C (122°F)
- Housing Material
- Metal
- Connection
- Direct Fit
- Features
- Designed for marine environment, corrosion resistant
What’s in the Box
- 1 x Thermostat (Replaces 688-12411)
- 1 x Thermostat Housing Gasket (Replaces 688-12414)
- 1 x Thermostat Seal (Replaces 688-12412)
Installation Notes
- Disconnect the battery and allow the engine to cool completely before starting work.
- Locate the thermostat housing on the engine block. You may need to remove a cover or other components for access.
- Place a drain pan beneath the housing and carefully loosen the bolts to drain any remaining coolant.
- Remove the old thermostat, gasket, and seal. Clean both the housing and cover mating surfaces thoroughly, removing all old gasket material.
- Install the new thermostat, ensuring it is oriented correctly. Place the new gasket and seal in their proper positions.
- Re-install the housing cover and tighten the bolts to the manufacturer's specified torque.
- Reconnect any components that were removed, refill the cooling system, and reconnect the battery.
- Start the engine and check for leaks around the housing as the engine warms up to operating temperature.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Common signs include engine overheating at low speeds, or taking too long to reach operating temperature. You may also see temperature gauge fluctuations or get an engine alarm.
What is the operating temperature of this thermostat?
This thermostat is rated to open at 50°C (122°F), regulating engine temperature for optimal performance in marine conditions.
Will this fit my specific Yamaha model?
This kit fits a wide array of Yamaha 2-stroke engines. Please check the "Engine & Model Compatibility" table above and cross-reference your exact model and year. Verifying the OEM part number is the most reliable way to ensure a match.
Is the gasket included?
Yes, this is a complete kit that includes the thermostat, thermostat housing gasket, and thermostat seal needed for a standard replacement.
Can I install this myself?
While installation is straightforward for those with mechanical experience, we recommend professional installation to ensure it is done correctly, preventing potential leaks or cooling system issues.
What is the difference between this thermostat and an OEM part?
This aftermarket thermostat is engineered to meet or exceed OEM specifications for fit, form, and function. It provides a reliable, cost-effective alternative to the original manufacturer's part.
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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