Yamaha Outboard Thermostat – 50°C, Fits 2-Stroke 75–250 HP (Replaces 6E5-12411-30, 688-12411-10, 688-12411-11)
Yamaha Outboard Thermostat – 50°C, Fits 2-Stroke 75–250 HP (Replaces 6E5-12411-30, 688-12411-10, 688-12411-11) is backordered and will ship as soon as it is back in stock.
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Yamaha Outboard Thermostat – 50°C, Fits 2-Stroke 75–250 HP (Replace...
Yamaha Outboard Thermostat – 50°C, Fits 2-Stroke 75–250 HP (Replaces 6E5-12411-30, 688-12411-10, 688-12411-11) is backordered and will ship as soon as it is back in stock.
Product Details
This Yamaha outboard thermostat is a 50°C replacement component for selected Yamaha two-stroke and two-stroke HPDI outboard engines. It helps regulate engine operating temperature by controlling coolant flow through the outboard cooling system.
The thermostat corresponds to Yamaha OEM part number 6E5-12411-30 and supersedes 688-12411-10 and 688-12411-11. Confirm the exact model designation and engine configuration before ordering.
- 50°C operating temperature.
- Replacement thermostat for selected Yamaha two-stroke outboards.
- Designed for service replacement in the thermostat housing.
- Thermostat only; gasket is not included unless specifically stated in the package contents.
Part Number References
These manufacturer part numbers identify the thermostat application covered by this listing. Part-number references do not replace verification of the complete engine model and configuration.
| Reference Type | Part Number |
|---|---|
| Current Yamaha OEM reference | 6E5-12411-30 |
| Superseded Yamaha reference | 688-12411-10 |
| Superseded Yamaha reference | 688-12411-11 |
Engine Compatibility
This thermostat is listed for the following Yamaha outboard models and configurations. The model, horsepower, stroke type and HPDI designation must all match your engine.
| Brand | Model | Rated HP | Stroke / Configuration | Operating Temperature |
|---|---|---|---|---|
| Yamaha | 75C | 75 HP | Two-Stroke | 50°C |
| Yamaha | 90A | 90 HP | Two-Stroke | 50°C |
| Yamaha | 100A | 100 HP | Two-Stroke | 50°C |
| Yamaha | 115C | 115 HP | Two-Stroke | 50°C |
| Yamaha | 130B | 130 HP | Two-Stroke | 50°C |
| Yamaha | 150F | 150 HP | Two-Stroke | 50°C |
| Yamaha | 175D | 175 HP | Two-Stroke | 50°C |
| Yamaha | 200F | 200 HP | Two-Stroke | 50°C |
| Yamaha | 200G | 200 HP | Two-Stroke | 50°C |
| Yamaha | 225D | 225 HP | Two-Stroke | 50°C |
| Yamaha | 250B | 250 HP | Two-Stroke | 50°C |
| Yamaha | Z150P | 150 HP | Two-Stroke HPDI | 50°C |
| Yamaha | Z150Q | 150 HP | Two-Stroke HPDI | 50°C |
| Yamaha | Z175G | 175 HP | Two-Stroke HPDI | 50°C |
| Yamaha | Z200N | 200 HP | Two-Stroke HPDI | 50°C |
| Yamaha | Z200P | 200 HP | Two-Stroke HPDI | 50°C |
Important: The compatibility information above is limited to the listed model designations. Do not assume compatibility with every Yamaha two-stroke engine within the same horsepower range.
Technical Specifications
- Product Type
- Outboard engine thermostat
- Operating Temperature
- 50°C
- Application
- Selected Yamaha two-stroke and two-stroke HPDI outboards
- OEM Reference
- 6E5-12411-30
- Supersedes
- 688-12411-10 and 688-12411-11
What's in the Box
- 1 x Thermostat
The thermostat housing gasket is not included. Replace the gasket during installation if the existing gasket is damaged, compressed or no longer seals correctly.
Installation Notes
- Allow the outboard engine to cool completely before beginning work.
- Disconnect the battery or otherwise follow the safety procedure specified in your engine service manual.
- Locate the thermostat housing and place a suitable container beneath the work area to catch residual water.
- Remove the housing cover carefully and note the position and orientation of the original thermostat.
- Clean the housing and cover sealing surfaces. Remove old gasket material and inspect the surfaces for corrosion or damage.
- Install the replacement thermostat in the same orientation as the original part. Follow the engine service manual for orientation details.
- Install a suitable new gasket if required. The gasket is not included with this thermostat.
- Reinstall the housing cover and tighten the fasteners to the manufacturer's specified torque.
- Run the engine using the correct water supply procedure for your outboard and check for leaks, proper water flow and abnormal temperature behavior.
Use the manufacturer's service manual for model-specific torque values, thermostat orientation and cooling-system procedures.
Troubleshooting & FAQ
What does the thermostat do?
The thermostat regulates coolant flow so the engine can operate within its intended temperature range. A thermostat that remains closed, remains open or operates inconsistently can affect engine temperature and cooling performance.
Is the gasket included?
No. This listing is for one thermostat. A thermostat housing gasket is not included and should be replaced separately when necessary.
How can I confirm compatibility?
Compare your complete Yamaha model designation and two-stroke or HPDI configuration with the compatibility table. Also compare the thermostat and housing against the original part before installation.
Can I use this thermostat on another Yamaha model with the same horsepower?
Not automatically. Horsepower alone does not confirm fitment. Use the exact model designations listed above and verify the OEM reference before ordering.
What are common signs of a thermostat problem?
Possible symptoms include abnormal operating temperature, overheating, running excessively cool or unstable temperature behavior. Other cooling-system problems can cause similar symptoms, so inspect the complete cooling system before replacing parts.
Safety & Important Information
- Verify the exact engine model, configuration and OEM reference before purchase.
- Never work on a hot engine or operate an outboard without the correct water supply.
- Follow the engine manufacturer's service instructions for installation, torque and testing.
- This is a replacement part and is not represented as a Yamaha-branded OEM component.
About Sea Sierra
- Marine Replacement Parts — Practical service components for routine outboard maintenance and repair.
- Application-Focused Listings — Compatibility information is presented by engine model and configuration where available.
- Service Support — Verify fitment and installation requirements before ordering or beginning repairs.
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