Yamaha 2-Stroke Outboard Thermostat Kit, 50°C – 75-250 HP (Replaces 6E5-12411-30-00, 688-12411 Series)
Yamaha 2-Stroke Outboard Thermostat Kit, 50°C – 75-250 HP (Replaces 6E5-12411-30-00, 688-12411 Series) is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
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.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Yamaha 2-Stroke Outboard Thermostat Kit, 50°C – 75-250 HP (Replaces...
Yamaha 2-Stroke Outboard Thermostat Kit, 50°C – 75-250 HP (Replaces 6E5-12411-30-00, 688-12411 Series) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket 50°C thermostat kit is designed for selected Yamaha 2-stroke outboard cooling systems using the Yamaha thermostat reference 6E5-12411-30-00 and related 688-12411-series references. It is intended for a range of Yamaha 2-stroke outboards from approximately 75 HP through 250 HP, including selected 115, 130, 150, 175, 200, 225, and 250 HP models.
The thermostat regulates engine operating temperature by opening at approximately 50°C (122°F). The kit includes the thermostat, thermostat-cover gasket, and thermostat seal for a convenient cooling-system service.
- Aftermarket replacement for selected Yamaha 2-stroke outboards.
- 50°C / 122°F thermostat specification.
- Kit includes the thermostat, cover gasket, and seal.
- Verify the exact engine model, year, and OEM reference before ordering.
Part Number Matrix
The following references are associated with this thermostat and kit configuration. Reference numbers are supplied for identification and cross-checking only; they do not replace model-specific fitment verification.
| Brand | Reference | Application |
|---|---|---|
| Yamaha | 6E5-12411-30-00 | Thermostat reference |
| Yamaha | 6E5-12411-30 | Thermostat reference format |
| Yamaha | 6E5-12411-20-00 | Superseded or related thermostat reference |
| Yamaha | 6E5-12411-10-00 | Superseded or related thermostat reference |
| Yamaha | 688-12411-10 / 688-12411-10-00 | Related thermostat reference |
| Yamaha | 688-12411-11 | Related thermostat reference |
| Yamaha | 688-12414-A1-00 | Thermostat-cover gasket reference |
| Sierra | 18-3540 | Aftermarket thermostat reference |
| Mallory | 9-43035 | Aftermarket cross-reference |
Engine & Model Compatibility
Catalog applications document this thermostat reference on numerous Yamaha 2-stroke models. The examples below are representative applications and are not a substitute for checking the complete model designation and year.
| Brand | Model examples | Rated HP | Stroke | Documented model years | Thermostat reference |
|---|---|---|---|---|---|
| Yamaha | 115TLR, 115TXR | 115 | 2-Stroke | 2003-2007 examples | 6E5-12411-30-00 |
| Yamaha | 130TLR, 130TXR | 130 | 2-Stroke | 2003-2004 examples | 6E5-12411-30-00 |
| Yamaha | 150TXR, V150TLR, VX150TLR, Z150TLR/TXR | 150 | 2-Stroke | 2003-2007 examples | 6E5-12411-30-00 |
| Yamaha | VZ150TLR, VZ175TLR, VZ200TLR | 150-200 | 2-Stroke | 2003-2007 examples | 6E5-12411-30-00 |
| Yamaha | Z175TXR, Z200TLR/TXR | 175-200 | 2-Stroke | 2003-2007 examples | 6E5-12411-30-00 |
| Yamaha | LZ200TXR, SX200TXR, VX200TLR | 200 | 2-Stroke | 2003-2007 examples | 6E5-12411-30-00 |
| Yamaha | LX225TXR, SX225TXR/TUR, VX225TLR | 225 | 2-Stroke | 2003-2004 examples | 6E5-12411-30-00 |
| Yamaha | LX250TXR, SX250TXR/TUR, VX250TLR | 250 | 2-Stroke | 2003-2004 examples | 6E5-12411-30-00 |
Important: Yamaha model suffixes identify important differences such as shaft configuration and production year. Check the complete model code, model year, serial-number range where applicable, and the original thermostat reference before installation. Do not assume that every Yamaha 2-stroke model within the same horsepower range uses the same thermostat.
Technical Specifications
- Product Type
- Aftermarket thermostat kit
- Thermostat Opening Temperature
- 50°C (122°F)
- Engine Type
- Selected Yamaha 2-stroke outboard engines
- Rated Application Range
- Selected applications from approximately 75 HP to 250 HP
- Installation
- Direct replacement when the OEM reference and model application match
- Kit Contents
- Thermostat, thermostat-cover gasket, and thermostat seal
- Product Status
- Aftermarket replacement; not an OEM Yamaha component
What's in the Box
- 1 x 50°C thermostat, equivalent to selected 6E5-12411-30-00 / 688-12411-series applications
- 1 x thermostat-cover gasket, associated with the 688-12414 reference
- 1 x thermostat seal
Installation Notes
- Switch off the engine, allow it to cool completely, and disconnect the negative battery cable where applicable.
- Refer to the service manual for the exact thermostat-housing location and removal procedure for your engine.
- Place a drain pan below the housing and drain enough cooling water to prevent spillage during disassembly.
- Remove the housing cover and carefully remove the old thermostat, gasket, and seal.
- Clean the mating surfaces completely. Do not scratch the housing or cover.
- Install the new thermostat in the same orientation as the original part, then install the new gasket and seal in their correct positions.
- Reinstall the cover and tighten the fasteners to the engine manufacturer's specified torque. Do not guess the torque value.
- Restore any removed components, reconnect the battery, and run the engine according to the service procedure.
- Check for leaks and confirm normal water flow and operating temperature before returning the boat to service.
Troubleshooting & FAQ
What temperature is this thermostat?
This thermostat is specified for approximately 50°C (122°F).
Is this an OEM Yamaha part?
No. This listing is for an aftermarket replacement kit intended for applications that match the listed OEM references and engine conditions.
Does the kit include the gasket and seal?
Yes. The kit includes one thermostat, one thermostat-cover gasket, and one thermostat seal.
Will this fit every Yamaha 2-stroke outboard from 75 to 250 HP?
No. The horsepower range is a general application guide only. Confirm the complete model code, year, serial-number range where applicable, and original thermostat reference before ordering.
How can I identify a failing thermostat?
Possible symptoms include overheating, abnormal temperature fluctuations, an engine that runs too cool, or an engine that takes too long to reach normal operating temperature. These symptoms can also be caused by restricted water passages, a damaged water pump, or other cooling-system faults.
Can I install it myself?
Installation should be performed by a qualified technician or by a person familiar with marine-engine service procedures. Always use the applicable service manual and the specified fastener torque.
What is the difference between this kit and a thermostat-only replacement?
This listing includes the thermostat together with the thermostat-cover gasket and seal, so the related sealing components can be replaced during the same service.
Safety & Important Information
- Verify the original part, complete engine model, model year, and serial-number range before purchase.
- Do not install a thermostat solely because the horsepower rating appears compatible.
- Allow the engine to cool before opening the cooling system.
- Follow the engine manufacturer's service instructions and torque specifications.
- This is an aftermarket replacement kit and is not manufactured or supplied by Yamaha.
About Sea Sierra
- Marine replacement parts selected for practical fit and service applications.
- Clear cross-reference information to help customers compare replacement parts.
- Support for routine outboard maintenance and cooling-system repairs.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
