Sierra 18-3831 Head Gasket for Yamaha 60 HP and 70 HP Outboards, Replaces 6H3-11181-01-00

The Sierra 18-3831 Head Gasket is a replacement head gasket engineered for Yamaha outboard motors, sealing the cylinder head to the block to maintain proper compression and prevent leaks between the combustion chamber and cooling passages. It fits Yamaha 60 (2001-05), P60 (1991-99), C60 (1996-01), E60 (1995-00), C70 (2000-01), and 70 (1984-09) engines, making it a direct fit for owners servicing these specific Yamaha outboard model years. Each package includes one gasket, sized precisely to match the original equipment sealing surface for a proper seal on installation.

This gasket is built to meet or exceed the specifications of the original equipment part it replaces, giving boat owners and marine technicians a reliable option when rebuilding a powerhead or addressing a compression or coolant leak. It cross-references directly to several OEM and aftermarket part numbers, so it can be ordered as a straightforward equivalent to the factory Yamaha gasket during a head gasket replacement or top-end rebuild.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3831
• Category: Yamaha Outboard Head Gaskets
• Weight: 0.19 pounds
• Product Dimensions: 0.39 x 0.39 x 0.39 inches
• UPC: 030999316820
• Quantity: One gasket per package

Fitment

• Yamaha 60 HP (2001-05)
• Yamaha P60 HP (1991-99)
• Yamaha C60 HP (1996-01)
• Yamaha E60 HP (1995-00)
• Yamaha C70 HP (2000-01)
• Yamaha 70 HP (1984-09)

Replaces (OEM)

• GLM 34940
• Mallory 9-63952
• Yamaha 6H3-11181-00-00
• Yamaha 6H3-11181-01-00
• Yamaha 6H3-11181-A0-00
• Yamaha 6H3-11181-A1-00
• Yamaha 6H3-11181-A2-00

Frequently Asked Questions

What engines does the Sierra 18-3831 head gasket fit? The Sierra 18-3831 fits Yamaha 60 HP (2001-05), P60 (1991-99), C60 (1996-01), E60 (1995-00), C70 (2000-01), and 70 (1984-09) outboard engines.

What OEM part numbers does this gasket replace? It replaces Yamaha 6H3-11181-00-00, 6H3-11181-01-00, 6H3-11181-A0-00, 6H3-11181-A1-00, and 6H3-11181-A2-00, and is also interchangeable with GLM 34940 and Mallory 9-63952.

How many gaskets come in one package? One Sierra 18-3831 head gasket is included per package.

Is the Sierra 18-3831 an OEM or aftermarket part? It is an aftermarket Sierra-brand head gasket built to meet or exceed the specifications of the original Yamaha equipment it replaces.

What are the dimensions of this head gasket? The Sierra 18-3831 measures 0.39 x 0.39 x 0.39 inches and weighs 0.19 pounds.

Will this gasket work on a Yamaha P60 outboard? Yes, the Sierra 18-3831 is designed to fit the Yamaha P60 (1991-99) engine along with the 60, C60, E60, C70, and 70 models listed for this part.

When would I need to replace this head gasket? A head gasket like the Sierra 18-3831 typically needs replacement when a powerhead is rebuilt or when symptoms of a blown gasket appear, such as compression loss or coolant leaking into the cylinder.

Does the Sierra 18-3831 cross-reference to a Mallory part number? Yes, Mallory 9-63952 is a direct cross-reference to the Sierra 18-3831 head gasket.

Is this gasket compatible with the Yamaha 70 HP outboard? The Yamaha 70 (1984-09) outboard is one of the engines this Sierra 18-3831 head gasket is designed to fit.

What is the UPC for the Sierra 18-3831 head gasket? The UPC for the Sierra 18-3831 head gasket is 030999316820.