Sierra 18-3608 Thermostat Kit, Replaces 6J8-12414-A0-00, for Yamaha 2-Stroke Outboard Engines

The Sierra 18-3608 Thermostat Kit is a complete cooling system repair kit for Yamaha 2-stroke outboard engines. Replacing a worn or stuck-open thermostat is one of the most common fixes for an outboard that runs cold, overheats, or shows erratic temperature swings, and this kit supplies both parts needed to do the job correctly in one purchase: a thermostat and the matching gasket. The thermostat is rated to open at 60 degrees Celsius, matching the original equipment opening temperature so the engine reaches and holds proper operating temperature for efficient combustion and long-term reliability.

Sierra engineers this kit to meet or exceed the original equipment part it replaces, so it installs the same way the factory thermostat and gasket did, with no modification required. Because the kit bundles the gasket with the thermostat, there is no need to source a separate gasket or risk reusing an old one that no longer seals properly. This is a direct fit for the Yamaha 2-stroke outboard cooling system application covered by part number 18-3608.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3608
• Product Type: Thermostat Kit
• Application: Yamaha 2-Stroke Outboard Engines
• Thermostat Temperature Rating: 60 degrees Celsius
• Kit Contents: Thermostat and gasket
• OEM Cross Reference: 6J8-12414-A0-00, 66M-12411-01-00, 62Y-12414-00-00
• Weight: 0.08 pounds
• UPC: 808282256807

Fitment

Yamaha 2-stroke outboard engines using the cooling system thermostat and gasket set covered by OEM number 6J8-12414-A0-00.

Replaces (OEM)

• 6J8-12414-A0-00
• 66M-12411-01-00
• 62Y-12414-00-00

Frequently Asked Questions

What is included in the Sierra 18-3608 thermostat kit? The 18-3608 kit includes a thermostat and the matching gasket needed to complete the cooling system repair, so no separate gasket purchase is required.

What temperature does the thermostat open at? The thermostat in the 18-3608 kit is rated to open at 60 degrees Celsius, matching the original equipment opening temperature for the Yamaha 2-stroke cooling system it services.

What OEM part numbers does the 18-3608 kit replace? This kit replaces OEM numbers 6J8-12414-A0-00, 66M-12411-01-00, and 62Y-12414-00-00.

What engines is the Sierra 18-3608 designed for? It is designed for Yamaha 2-stroke outboard engines that use the cooling system thermostat and gasket covered by OEM number 6J8-12414-A0-00.

How much does the 18-3608 thermostat kit weigh? The Sierra 18-3608 Thermostat Kit weighs 0.08 pounds.

Is the Sierra 18-3608 a genuine OEM part or an aftermarket replacement? It is a Sierra aftermarket kit engineered to meet or exceed the original equipment part it replaces, so it installs and performs the same as the factory thermostat and gasket.

Does the kit come with the gasket, or just the thermostat? Both are included: the 18-3608 kit contains the thermostat and its matching gasket in a single package.

What is the UPC for this product? The UPC for the Sierra 18-3608 Thermostat Kit is 808282256807.

How do I confirm the 18-3608 kit fits my Yamaha outboard? Check that your engine's original thermostat or gasket carries the OEM number 6J8-12414-A0-00, 66M-12411-01-00, or 62Y-12414-00-00, since the 18-3608 kit replaces all three.

Does the Sierra 18-3608 include a warranty? Yes, the Sierra 18-3608 Thermostat Kit is covered under Sierra's standard limited warranty.

Can the 18-3608 kit be installed without modifying the engine? Yes, the 18-3608 thermostat and gasket are designed as a direct replacement, installing the same way as the original equipment parts with no modification needed.