Yamaha Outboard Thermostat – Fits Yamaha 2-Stroke 3-250HP (Replaces 6E5-12411-30-00, 6E5-12411-20-00)

Yamaha Outboard Thermostat – Fits Yamaha 2-Stroke 3-250HP

This thermostat is designed to fit a wide range of Yamaha 2-Stroke outboard engines from 9.9HP to 250HP (model years 1994–2011), as well as Yamaha HPDI 2-Stroke Z150–Z200HP high-pressure direct injection models.

It serves as a direct replacement for multiple Yamaha OEM part numbers, including 6E5-12411-30-00, 6E5-12411-20-00, 6E5-12411-10-00, 688-12411-10-00, 688-12411-11-00, 688-12411-00-00, 688-12411-01-00, and 6H3-12411-00-00.

• Installation: Direct OEM Replacement
• Housing Material: Brass
• Fuel Type Compatibility: Gasoline

Compatible Engine Models

Confirm your engine model/year in the table below. For Yamaha owners, here’s a guide to help you identify your engine’s serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

Technical Specifications

Package Contents

1 x Thermostat (6E5-12411-30-00)
Note: Gasket is not included and may need to be purchased separately.

Installation Guide

1. Ensure the engine is completely cool before starting.
2. Disconnect the negative battery cable for safety.
3. Locate the thermostat housing on the engine block.
4. Place a drain pan underneath and remove the housing cover bolts.
5. Carefully lift the cover, noting the orientation of the old thermostat.
6. Remove the old thermostat and gasket.
7. Thoroughly clean the mating surfaces of both the housing and the cover.
8. Install the new thermostat, ensuring it is in the correct orientation.
9. Place the new gasket and reinstall the housing cover, tightening the bolts to the manufacturer's specified torque.
10. Reconnect the battery cable.
11. Start the engine in a well-ventilated area and check for any leaks around the housing.
12. Allow the engine to reach operating temperature to confirm the new thermostat is functioning correctly.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my Yamaha engine?
A: Check your engine's model, year, and horsepower against the "Compatible Engine Models" table. You should also verify that your existing part number matches one of the numbers listed as a direct replacement, such as 6E5-12411-30-00, 6E5-12411-20-00, or 688-12411-10-00.

Q: What are the signs of a failing outboard thermostat?
A: Common signs include the engine overheating at idle or low speeds, or taking too long to reach its proper operating temperature. You might also notice inconsistent readings on the temperature gauge or receive an overheat alarm.

Q: Is a gasket included with this thermostat?
A: This package contains only the thermostat. The housing gasket is not included and typically needs to be purchased separately to ensure a proper seal.

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.