Thermostat – Fits Yamaha 2-Stroke Outboard 75-250 HP (Replaces 6E5-12411-30-00, 688-12411 Series)
Thermostat – Fits Yamaha 2-Stroke Outboard 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.
Thermostat – Fits Yamaha 2-Stroke Outboard 75-250 HP (Replaces 6E5-...
Thermostat – Fits Yamaha 2-Stroke Outboard 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 replacement Thermostat – Fits Yamaha 2-Stroke Outboard 75-250 HP (Replaces 6E5-12411-30-00, 688-12411 Series) is engineered for a wide range of Yamaha 2-stroke outboard engines from 1991 to 2005, including LZ, SX, VX, VZ, and Z series models. It ensures your engine maintains the correct operating temperature for optimal performance and fuel efficiency.
It serves as a direct cross-reference for Yamaha part numbers 6E5-12411-30-00, 6E5-12411-20-00, 6E5-12411-10-00, and the 688-12411 series, as well as aftermarket equivalents like Sierra 18-3540 and Mallory 9-43035.
- Designed for direct-fit installation.
- Opens at a rated temperature of 50°C / 122°F.
- Kit includes thermostat, housing gasket, and seal.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 6E5-12411-30-00 | Current Number |
| Yamaha | 6E5-12411-20-00 | Superseded by 6E5-12411-30-00 |
| Yamaha | 6E5-12411-10-00 | Superseded by 6E5-12411-20-00 |
| Yamaha | 688-12411-11 | Interchangeable |
| Yamaha | 688-12411-10 | Interchangeable |
| Yamaha | 688-12411-01 | Interchangeable |
| Yamaha | 688-12411-00 | Interchangeable |
| Sierra | 18-3540 | Aftermarket Interchange |
| Mallory | 9-43035 | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part is designed specifically for Yamaha outboards listed.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 115TLR | 115 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Including models 115TLRB, 115TLRC, 115TLRD |
| Yamaha | 115TXR | 115 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Including models 115TXRB, 115TXRC, 115TXRD |
| Yamaha | 130TLR/TXR | 130 | 2-Stroke | 2003–2004 | 6E5-12411-30-00 | Including models 130TLRB, 130TLRC, 130TXRB, 130TXRC |
| Yamaha | 150TXR | 150 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Including models 150TXRB, 150TXRC, 150TXRD |
| Yamaha | 15MSH | 15 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Including models 15MSHB, 15MSHC, 15MSHD |
| Yamaha | 25ELH/ELR/ESH/ESR/MLH/MSH | 25 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Multiple variants including 25MSHB, 25MSHC, 25MSHD |
| Yamaha | 40TLRB/C/D | 40 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Including 40TLRNC (2004) |
| Yamaha | 50TLR | 50 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Including models 50TLRB, 50TLRC, 50TLRD, 50TLRNC |
| Yamaha | 9.9MSH | 9.9 | 2-Stroke | 2003–2009 | 6E5-12411-30-00 | Including models 9.9MSHB, 9.9MSHC, 9.9MSHD |
| Yamaha | C40TLRB | 40 | 2-Stroke | 2003 | 6E5-12411-30-00 | |
| Yamaha | DX150TLR | 150 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Including models DX150TLRB, DX150TLRC, DX150TLRD |
| Yamaha | LX225/250TXRB | 225/250 | 2-Stroke | 2003 | 6E5-12411-30-00 | |
| Yamaha | LZ150TXR | 150 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Including models LZ150TXRB, LZ150TXRC, LZ150TXRD |
| Yamaha | LZ200TXR | 200 | 2-Stroke | 2003–2012 | 6E5-12411-30-00 | Multiple model years through 2012 |
| Yamaha | SX150/200/225/250 | 150-250 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Various SX models and years |
| Yamaha | V150TLR | 150 | 2-Stroke | 2003–2008 | 6E5-12411-30-00 | Including models V150TLRB, V150TLRC, V150TLRD |
| Yamaha | VX150/200/225/250 | 150-250 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Various VX models and years |
| Yamaha | VZ150TLR | 150 | 2-Stroke | 2003–2014 | 6E5-12411-30-00 | Multiple model years through 2014 |
| Yamaha | VZ175TLR | 175 | 2-Stroke | 2003–2012 | 6E5-12411-30-00 | Multiple model years through 2012 |
| Yamaha | VZ200TLR | 200 | 2-Stroke | 2003–2004 | 6E5-12411-30-00 | Including models VZ200TLRB, VZ200TLRC |
| Yamaha | Z150TLR/TXR | 150 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Multiple Z150 variants |
| Yamaha | Z175TXR | 175 | 2-Stroke | 2003–2005 | 6E5-12411-30-00 | Including models Z175TXRB, Z175TXRC, Z175TXRD |
| Yamaha | Z200TLR/TXR | 200 | 2-Stroke | 2003–2012 | 6E5-12411-30-00 | Multiple model years and variants |
Technical Specs
- Product Type
- Outboard Engine Thermostat
- Installation
- Direct Replacement
- Temperature Rating
- 50°C / 122°F
- Housing Material
- Metal
- Operating Temperature
- 50°C / 122°F (opening temperature)
What’s in the Box
- 1 x Thermostat (Replaces 6E5-12411-30-00 / 688-12411 series)
- 1 x Thermostat Housing Gasket (Replaces 688-12414-A1 / A0 / 00)
- 1 x Thermostat Seal (Replaces 688-12412)
Installation Notes
- Disconnect the negative battery cable before starting work.
- Allow the engine to cool completely. Locate and place a drain pan under the thermostat housing.
- Remove the thermostat housing cover bolts and gently tap the cover to break the seal.
- Note the orientation of the old thermostat’s bleed hole or jiggle valve before removing it.
- Thoroughly clean both the housing and cover mating surfaces to remove all old gasket material.
- Install the new thermostat in the correct orientation, followed by the new gasket and seal.
- Reinstall the housing cover and tighten the bolts to the manufacturer’s specified torque.
- Refill the cooling system, restart the engine, and check for leaks and proper temperature.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Common signs of a faulty thermostat include engine overheating (stuck closed) or the engine not reaching its proper operating temperature (stuck open), which can lead to poor performance, increased carbon buildup, and higher fuel consumption.
Is this the correct temperature rating for my engine?
This thermostat is rated to open at 50°C (122°F), which is the specified temperature for the listed Yamaha models. Using a thermostat with an incorrect temperature rating can harm your engine.
My exact model variant isn't listed, will this still fit?
If your model is not explicitly listed in the compatibility table, we do not recommend purchasing this part. Always verify fitment by matching your engine's required OEM part number to the numbers in our Part Number Matrix.
What is the recommended replacement interval for a thermostat?
While thermostats can last for many years, it's good practice to inspect them during routine cooling system service or replace them every 3-5 years, especially if operating in saltwater, to prevent unexpected failure.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9002 facility, then batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit is 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
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
