Sierra Head Gasket 18-3805, Replaces Yamaha 6H1-W0001-00-00, for Yamaha Outboard Engines

The Sierra 18-3805 is a head gasket engineered as a direct replacement for Yamaha outboard engines. It seals the mating surface between the cylinder head and the powerhead block, maintaining compression and preventing coolant or combustion leaks at this critical joint. As a precision-fit replacement part, it is built to the same sealing tolerances as the original equipment it replaces, making it a straightforward swap when servicing a Yamaha outboard head gasket that has failed or is being replaced as routine maintenance during a top-end rebuild.

This head gasket is cataloged under the Yamaha Outboard Head Gaskets category and cross-references directly to Yamaha OEM part numbers, so it can be ordered with confidence as an equivalent to the factory gasket. It is a lightweight, single-component part designed for straightforward removal and installation using standard outboard service procedures and correct torque specifications.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3805
• Product Type: Head Gasket
• Category: Yamaha Outboard Head Gaskets
• Weight: 0.21 pounds
• UPC: 030999316561

Fitment

Designed for Yamaha outboard engines; specific model, horsepower, and year fitment should be confirmed against the OEM cross-reference numbers below.

Replaces (OEM)

• 6H1-W0001-00-00
• 6H1-W0001-01-00
• 6H1-W0001-A0-00
• 688-11181-02-00

Frequently Asked Questions

What does the Sierra 18-3805 head gasket fit? The Sierra 18-3805 is designed for Yamaha outboard engines and is cataloged as a Yamaha Outboard Head Gasket, cross-referencing directly to Yamaha OEM part numbers.

What OEM Yamaha part numbers does 18-3805 replace? Part 18-3805 replaces Yamaha OEM numbers 6H1-W0001-00-00, 6H1-W0001-01-00, 6H1-W0001-A0-00, and 688-11181-02-00.

Is the Sierra 18-3805 a genuine Yamaha part or aftermarket? The 18-3805 is a Sierra-branded replacement gasket, not an OEM Yamaha part, but it is built to match the OEM Yamaha specifications and cross-references directly to the Yamaha part numbers it replaces.

How much does the 18-3805 head gasket weigh? The Sierra 18-3805 head gasket weighs 0.21 pounds.

What is the UPC for the Sierra 18-3805 head gasket? The UPC for the Sierra 18-3805 head gasket is 030999316561.

Where does the 18-3805 gasket install on the engine? It installs between the cylinder head and the powerhead block on a Yamaha outboard, sealing that joint to maintain compression and prevent coolant or combustion leaks.

Can I use the 18-3805 gasket for a top-end rebuild? Yes, the Sierra 18-3805 head gasket is suitable for use during a Yamaha outboard top-end rebuild or whenever the head gasket needs replacing due to a failed seal.

What product category does 18-3805 belong to? Sierra part 18-3805 is listed under the Yamaha Outboard Head Gaskets category.

Does the 18-3805 head gasket come with other gaskets or seals? The 18-3805 is sold as the head gasket itself; it is a single-item part identified by its own Yamaha OEM cross-reference (688-11181-02-00) rather than a multi-piece kit.

How do I confirm the 18-3805 is correct for my Yamaha outboard? Match the OEM number stamped or listed for your Yamaha outboard against the cross-references for 18-3805: 6H1-W0001-00-00, 6H1-W0001-01-00, 6H1-W0001-A0-00, or 688-11181-02-00.