Sierra 18-3622 Thermostat Kit for Yamaha Outboards, Replaces 6H3-12411-11-00, 122F

The Sierra 18-3622 Thermostat Kit is a replacement thermostat and gasket set designed for Yamaha outboard engines. The kit includes a thermostat with a 122 degrees F (50 degrees C) opening temperature along with a matching thermostat cover gasket (Sierra 18-0835), giving you everything needed to restore proper cooling system operation in one package. Maintaining correct thermostat function is critical on an outboard: it regulates engine warm-up and keeps operating temperature within the range the engine was designed for, protecting against overheating and reducing wear caused by running too cold or too hot.

This kit is built to meet or exceed the specifications of the original equipment thermostat it replaces, making it a straightforward swap for the OEM part. The included gasket ensures a proper seal at the thermostat cover, so there is no need to source a separate gasket for the job. It is finished in white and sized to fit directly into the Yamaha thermostat housing it is designed for.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3622
• Product Type: Thermostat Kit
• Temperature Rating: 122 degrees F / 50 degrees C
• Color: White
• Included Components: Thermostat, 1 thermostat cover gasket (Sierra 18-0835)
• Weight: 0.07 pounds
• OEM Cross-Reference: Yamaha 6H3-12411-11-00

Fitment

• Yamaha outboard engines using thermostat 6H3-12411-11-00

Replaces (OEM)

• 6H3-12411-11-00

Frequently Asked Questions

What engines does the Sierra 18-3622 Thermostat Kit fit? The 18-3622 kit is designed for Yamaha outboard engines that use OEM thermostat 6H3-12411-11-00.

What is the opening temperature of this thermostat? The thermostat in the Sierra 18-3622 kit opens at 122 degrees F (50 degrees C).

Does the 18-3622 kit include a gasket? Yes, one thermostat cover gasket, Sierra part 18-0835, is included with the 18-3622 kit so you do not need to buy a gasket separately.

What OEM part number does the Sierra 18-3622 replace? It replaces Yamaha OEM thermostat number 6H3-12411-11-00.

Is the Sierra 18-3622 a genuine Yamaha part or aftermarket? The 18-3622 is a Sierra-branded aftermarket thermostat kit built to meet or exceed the performance of the original Yamaha 6H3-12411-11-00 thermostat.

How much does the thermostat kit weigh? The Sierra 18-3622 Thermostat Kit weighs 0.07 pounds.

What color is the thermostat housing or components? The components in the 18-3622 kit are white.

Do I need any other parts to complete a thermostat replacement with this kit? The 18-3622 kit includes both the thermostat and its cover gasket (18-0835), covering the parts most commonly needed for a thermostat swap on the applicable Yamaha outboard.

Can I use the 18-3622 thermostat if my engine runs warmer or cooler than 122 degrees F? The Sierra 18-3622 is built to a fixed 122 degrees F (50 degrees C) opening rating; a different temperature rating would require a different Sierra thermostat kit.

Is thermostat 18-3622 different from Sierra 18-3621 or 18-3623? Yes, 18-3622 is a distinct Sierra part number from 18-3621 and 18-3623; each corresponds to a different OEM Yamaha thermostat, so confirm your engine's OEM number before ordering.