SKU: 77700815977

6F5-12411-03 Thermostat Kit for Yamaha 25D | JLM Marine

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Description

6F5-12411-03 Thermostat Kit for Yamaha 25D | JLM MarineThermostat Kit for Yamaha 25D 6F5 12411 03 This thermostat kit is designed for Yamaha 2 stroke 25D outboard engines, providing reliable temperature regulation to protect your motor from overheating. It includes all essential components for a complete thermostat service, ensuring proper cooling system performance and engine longevity. This kit directly replaces multiple Yamaha OEM part numbers, including 6F5 12411 01, 6F5 12411 02, and 6F5 12411 03,

Thermostat Kit for Yamaha 25D – 6F5-12411-03

This thermostat kit is designed for Yamaha 2-stroke 25D outboard engines, providing reliable temperature regulation to protect your motor from overheating. It includes all essential components for a complete thermostat service, ensuring proper cooling system performance and engine longevity.

This kit directly replaces multiple Yamaha OEM part numbers, including 6F5-12411-01, 6F5-12411-02, and 6F5-12411-03, along with compatible housing gaskets. It offers a cost-effective aftermarket solution for maintaining your outboard's cooling system.

  • Complete service kit with thermostat, seal, and housing gasket
  • Direct replacement for Yamaha OEM part numbers
  • Designed for Yamaha 2-stroke 25D outboards

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Brand Part Number Notes
Yamaha 6F5-12411-01 Outboard Thermostat
Yamaha 6F5-12411-02 Outboard Thermostat
Yamaha 6F5-12411-03 Outboard Thermostat
Yamaha 61A-12414-A0 Thermostat Housing Gasket
Yamaha 6H4-12414-00 Thermostat Housing Gasket
Yamaha 6H4-12414-A0 Thermostat Housing Gasket
Yamaha 6J8-12414-A0 Thermostat Housing Gasket

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.

Brand Model Stroke
Yamaha 25D 2-Stroke

Technical Specifications

Specification Value
OEM Part Number 6F5-12411-03
Fits Brand Yamaha
Engine Type 2-Stroke Outboard
Compatible Models 25D

Package Contents

This complete thermostat service kit includes:

  • 1 × Outboard Thermostat
  • 1 × Thermostat Seal
  • 1 × Thermostat Housing Gasket (Gasket color may be black or blue, but the material is the same)

Installation Guide

  1. Disconnect the battery and allow the engine to cool completely before beginning work.
  2. Locate the thermostat housing on your Yamaha 25D outboard, typically on the cylinder head or mid-section.
  3. Remove the bolts securing the thermostat housing cover using the appropriate socket or wrench.
  4. Carefully lift off the housing cover and remove the old thermostat and gasket. Inspect the housing for corrosion or damage.
  5. Clean all mating surfaces thoroughly, removing old gasket material and debris to ensure a proper seal.
  6. Install the new thermostat seal onto the thermostat, ensuring it seats correctly in the groove.
  7. Position the new thermostat into the housing with the temperature-sensing element (spring side) facing the correct direction as indicated by the old unit.
  8. Place the new thermostat housing gasket onto the housing, aligning all bolt holes properly.
  9. Reinstall the thermostat housing cover, ensuring proper alignment with the gasket.
  10. Tighten the housing bolts in a crisscross pattern to the manufacturer's recommended torque specification to prevent warping.
  11. Reconnect the battery and start the engine, allowing it to reach operating temperature while monitoring for leaks.
  12. Check coolant levels and top off if necessary, then verify proper engine temperature operation.

Troubleshooting & FAQ

Q: How do I confirm this thermostat kit fits my Yamaha outboard?
A: Verify that your engine is a Yamaha 2-stroke 25D model. Cross-reference your current thermostat part number with the listed OEM numbers (6F5-12411-01, 6F5-12411-02, 6F5-12411-03) to ensure compatibility.

Q: How often should I replace my outboard thermostat?
A: Thermostats should be inspected annually and replaced every 2-3 years or when you notice overheating issues, inconsistent temperature readings, or visible corrosion. Regular replacement prevents costly engine damage from cooling system failure.

Q: What are the signs that my thermostat is failing?
A: Common symptoms include engine overheating, running too cool (prolonged warm-up), steam from the engine, reduced performance, or the overheat alarm activating. If you experience any of these, inspect and replace the thermostat immediately.

Q: Why does the gasket color vary between black and blue?
A: The gasket color may vary by production batch, but both black and blue gaskets are manufactured from the same material specification and provide identical sealing performance. Use whichever color is supplied in your kit with confidence.

Q: Is this an OEM part or aftermarket replacement?
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.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 77700815977

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4.8 ★★★★★
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Adam
Charlottesville, US
★★★★★ 4
Fantastic pillow for the price, adjustable is a different ball-game entirely.
Size: Queen (1 Count), Color: White
Overall, I'm quite pleased with this. The fact that it is fully adjustable (adding or removing foam, and they give you a bunch extra) is a massive boon as I like pillows to be pretty low profile. It feels nice to the touch, and compresses nicely but not a ton like down. The memory foam that is inside of it seems to be combined with some kind of a harder material, it's all shredded so I can't tell what it is, but it seems like maybe plastic or something of the kind. Hasn't been an issue in any way, but was just weird feeling it when removing foam. I took a point off because there seems to be some false advertising going on. You can see in their picture that there is a tag that says bamboo side, the other side of that says cooling side. They also mention it in their advertising. As far as I can tell that is not true at all. The cover unzips so that you can remove the material so you can see that there is nothing on either side of it, and both sides appear visually identical to each other. Certainly I would NOT call this a cooling pillow in any way. It's maybe decently cool if you leave it in a cool place for a while, but over the course of the night warms up quite a bit. I did not notice any appreciable difference in the cooling of either side of it. There is a definite noticeable smell to it, but I wouldn't call it 'bad' like most memory foam things are when they come from the factory. It smells kind of like some kind of cleaning solution in a noticeable but not unpleasant sense. All in all, for the price this is a fantastic pillow and I would definitely recommend it.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 14, 2026
J
Verified Purchase
Joshua Sojka
Lake Worth, US
★★★★★ 5
Most Comfy Pillow Ever Used
Size: King Size Pack of 2, Color: White
I recently purchased the BETU Cooling King Size Pillows Set of 2, and I have been thoroughly impressed with their quality and performance. These pillows have truly transformed my sleeping experience, making them an essential addition to my bedroom. First and foremost, the shredded memory foam provides fantastic support while remaining incredibly comfortable. These pillows adapt perfectly to my head and neck, offering excellent support for back, neck pain relief, and side sleeping. The adjustability of the memory foam allows me to customize the firmness to my liking, ensuring a perfect balance between soft and firm support. This customization has made a tremendous difference in my sleep quality, reducing any discomfort and ensuring I wake up feeling refreshed and pain-free. One of the standout features of these pillows is their cooling capability. As a hot sleeper, I struggled to find pillows that keep me cool throughout the night. The BETU Cooling Pillows effectively dissipate heat and maintain a comfortable temperature, allowing me to enjoy a restful and uninterrupted sleep. The cooling technology is truly a game-changer for anyone who tends to overheat during the night. The pillow covers are another bonus. They are soft, breathable, and easily removable for washing, ensuring that the pillows remain fresh and hygienic. The white cover adds a clean and elegant look to the bedding, making them aesthetically pleasing as well. The king size is generous and luxurious, providing ample space and comfort. Whether used for sleeping, lounging, or reading in bed, these pillows offer an unparalleled level of comfort and support. In summary, the BETU Cooling King Size Pillows Set of 2 is an exceptional product. The combination of shredded memory foam, adjustable firmness, and cooling technology makes these pillows perfect for hot sleepers and those in need of superior support for back and neck pain. The high-quality covers and overall design further enhance their value. I highly recommend these pillows to anyone looking to improve their sleep quality and comfort.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on July 31, 2025
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Verified Purchase
Chemom
Dallas, US
★★★★★ 5
Cooling pillow
Size: Queen (1 Count), Color: White
Good pillow very comfy and cool. Good quality material very durable. I love using it. Perfect size!
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on June 5, 2026
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zhaoxingwei
West Palm Beach, US
★★★★★ 5
Cool, Supportive, and Great for Hot Sleepers
Size: Queen Size Pack of 2, Color: White
These cooling pillows have been a great upgrade for my sleep. The shredded memory foam provides nice support while still feeling soft and adjustable. I like that the pillows keep their shape and don’t go flat during the night. The cooling fabric really helps if you tend to sleep warm. They feel breathable and comfortable, especially compared to traditional memory foam pillows that trap heat. The queen size is generous and works well for both side and back sleeping. Overall, a great value for a set of two pillows. Comfortable, supportive, and noticeably cooler than my old ones. I would definitely buy them again.
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Reviewed in the United States on March 6, 2026
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Raven
Lake Worth, US
★★★★★ 3
Great pillows, needs more filler tho!
Size: King Size Pack of 2, Color: White
Partner says it's the best thing that's ever happened and has helped his back/shoulder pain tremendously. I personally think it needs to give you more fluff or whatever the filling is. Because the tiny bag that comes btwn the two was not enough! However, still comfy, filling is nice and fluffy like a cloud.
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Reviewed in the United States on March 25, 2026

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