SKU: 95382020862

Marine Thermostat – Fits Yamaha F300/F350 4-Stroke V8 Outboards (Replaces 6AW-12411-00-00)

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Description

Marine Thermostat – Fits Yamaha F300/F350 4-Stroke V8 Outboards (Replaces 6AW-12411-00-00)Marine Thermostat Fits Yamaha F300 F350 4 Stroke V8 Outboards This marine thermostat is designed for Yamaha 4 Stroke 300HP & 350HP V8 outboards manufactured between 2007 and 2018. It ensures your engine maintains the correct operating temperature for optimal performance and longevity. It serves as a direct replacement for Yamaha part number 6AW 12411 00 00 and Sierra part number 18 3634. Installation Method: Direct OEM style fit Operating Temperature:

Marine Thermostat – Fits Yamaha F300/F350 4-Stroke V8 Outboards

This marine thermostat is designed for Yamaha 4-Stroke 300HP & 350HP V8 outboards manufactured between 2007 and 2018. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.

It serves as a direct replacement for Yamaha part number 6AW-12411-00-00 and Sierra part number 18-3634.

  • Installation Method: Direct OEM-style fit
  • Operating Temperature: 60°C / 140°F
  • Compatible Fuel Type: Gasoline

Part Number Cross-Reference

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

Brand Part Number
Yamaha 6AW-12411-00-00
Sierra 18-3634

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 Rated HP Stroke Years OEM Part No.
Yamaha F300TUR 300 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha F300TXR 300 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha LF300TUR 300 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha LF300TXR 300 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha F350TUR 350 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha F350TXR 350 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha LF350TUR 350 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha LF350TXR 350 4-Stroke 2007–2009 6AW-12411-00-00
Yamaha F350AET1U 350 4-Stroke 2010 6AW-12411-00-00
Yamaha F350AET1X 350 4-Stroke 2010 6AW-12411-00-00
Yamaha FL350AET1U 350 4-Stroke 2010 6AW-12411-00-00
Yamaha FL350AET1X 350 4-Stroke 2010 6AW-12411-00-00
Yamaha F350UCA 350 4-Stroke 2010–2011 6AW-12411-00-00
Yamaha F350XCA 350 4-Stroke 2010–2011 6AW-12411-00-00
Yamaha LF350UCA 350 4-Stroke 2010–2011 6AW-12411-00-00
Yamaha LF350XCA 350 4-Stroke 2010–2011 6AW-12411-00-00
Yamaha F350UCB 350 4-Stroke 2012–2015 6AW-12411-00-00
Yamaha F350XCB 350 4-Stroke 2012–2015 6AW-12411-00-00
Yamaha LF350UCB 350 4-Stroke 2012–2015 6AW-12411-00-00
Yamaha LF350XCB 350 4-Stroke 2012–2015 6AW-12411-00-00
Yamaha F350NCB 350 4-Stroke 2014–2015 6AW-12411-00-00
Yamaha F350UCC 350 4-Stroke 2016–2018 6AW-12411-00-00
Yamaha F350XCC 350 4-Stroke 2016–2018 6AW-12411-00-00
Yamaha F350NCC 350 4-Stroke 2016 6AW-12411-00-00
Yamaha LF350UCC 350 4-Stroke 2016–2018 6AW-12411-00-00
Yamaha LF350XCC 350 4-Stroke 2016–2018 6AW-12411-00-00

Technical Specifications

Product Type Marine Thermostat
Installation Direct OEM Replacement
Fuel Type Gasoline
Operating Temperature 60°C / 140°F
Other Technical Attributes For Yamaha V8 outboard cooling systems

Package Contents

  • 1 × 60°C / 140°F Outboard Thermostat (Replaces OEM Part #6AW-12411-00-00)

Installation Guide

  1. Safety First: Ensure the engine is completely cool and disconnect the battery before starting.
  2. Drain Coolant: Place a container under the engine and carefully drain the cooling system to a level below the thermostat housing.
  3. Locate Housing: Identify the thermostat housing on the engine block. It is typically connected to the main coolant hoses.
  4. Remove Housing Cover: Loosen and remove the bolts securing the thermostat housing cover. Note the orientation of the cover and gasket.
  5. Remove Old Thermostat: Carefully lift out the old thermostat and gasket. Clean any sealant residue or corrosion from the housing surfaces.
  6. Install New Thermostat: Place the new thermostat into the housing, ensuring it is oriented correctly (the spring side usually faces the engine). Install the new gasket.
  7. Reassemble: Secure the housing cover and tighten the bolts to the manufacturer's recommended torque specification. Do not overtighten.
  8. Refill and Check: Reconnect hoses if they were removed. Refill the cooling system with the appropriate coolant.
  9. Final Inspection: Reconnect the battery. Start the engine and let it warm up, carefully checking for any leaks around the thermostat housing. Top off coolant if necessary.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my engine?

A: First, check the 'Compatible Engine Models' table on this page to ensure your specific engine model and year range are listed. Second, cross-reference the OEM part number 6AW-12411-00-00 with the part number specified in your engine’s service manual.

Q: What are the common signs of a failing thermostat?

A: Key symptoms include engine overheating alarms, the temperature gauge reading higher or lower than normal, or the engine taking an unusually long time to reach its standard operating temperature. A thermostat stuck open can cause the engine to run too cool, while one stuck closed will lead to overheating.

Q: How often should I replace my outboard's thermostat?

A: As a preventative maintenance measure, we recommend inspecting your thermostat annually and replacing it every 2-3 years, or according to the service interval in your owner's manual. Replacement is especially important for engines used in saltwater environments, where corrosion can cause parts to fail prematurely.

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.
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
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