Yamaha Thermostat 6H3-12411-20-00 - Special Order
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The Yamaha 6H3-12411-20-00 is an OEM thermostat for select Yamaha two-stroke outboard cooling systems. It regulates engine operating temperature by controlling coolant/water flow through the cylinder head or cooling passage as specified in the Yamaha parts diagram.
Key Features
- Yamaha OEM thermostat
- Part number: 6H3-12411-20-00
- Used in select Yamaha two-stroke outboard applications
- Fits listed small Yamaha outboard model families including 3A, 4A, 5C, 6C, 6D, 6J, 8C, and 8J
- Also listed for 8MSH model-code ranges including 0405, 0406, 0407, and 0608
- Cooling-system service part for thermostat housing / cylinder-head cooling passages
Engine Compatibility
Fits select Yamaha two-stroke outboard models including:
- 3A
- 4A
- 5C
- 6C / 6D / 6J
- 8C / 8J
- 8MSH-0405
- 8MSH-0406
- 8MSH-0407
- 8MSH-0608
Use where the Yamaha parts diagram calls for 6H3-12411-20-00.
Serial Number Fitment Notice
Confirm fitment by Yamaha model code, serial number, and thermostat/cooling-system diagram before ordering. Yamaha two-stroke thermostat applications can vary by horsepower, model suffix, and production range.
When This Part Needs Replacement
Replace when the engine runs too cold, overheats, has weak or irregular cooling behavior, shows corrosion around the thermostat, or when the thermostat is stuck open or closed. It is also commonly replaced during cooling-system service.
Installation Notes
Inspect the thermostat cover, gasket or seal, housing surface, and cooling passages during replacement. Remove corrosion or debris from the thermostat pocket before installation and follow the Yamaha service manual for orientation and testing procedure.
Alternate/Superseded Part Numbers
- Yamaha 6H3-12411-20-00
Parts Desk Insight
This thermostat should be matched to the Yamaha model code and cooling-system diagram, not horsepower alone. Small two-stroke Yamaha outboards often share similar cooling parts, but thermostat fitment still depends on the exact model family and production range.
Special Order: This product is not currently in store inventory but may be available from the Manufacturer. Special Orders may take up to 2 weeks to arrive. Call the parts desk before ordering if you need a closer estimate on delivery time.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.