Sierra 18-0645 Adapter Plate Gasket for Mercury/Mariner Outboard Motors, White

The Sierra 18-0645 Adapter Plate Gasket is a replacement gasket engineered for Mercury and Mariner outboard motors. It seals the adapter plate joint on the powerhead, helping maintain a proper seal against water and combustion gases so the engine runs as designed. The gasket is manufactured to OEM specifications, meaning it is built to meet or exceed the performance of the original equipment part it replaces, giving boat owners a dependable option when servicing the adapter plate area during a rebuild, tune-up, or routine maintenance.

Finished in white and featuring a round profile to match the adapter plate mounting pattern, this gasket is designed for a straightforward, direct-fit installation without modification. Sierra builds this part to stand up to the demanding conditions of the marine environment, including exposure to fuel, oil, heat, and moisture, so it holds its seal over time. As a fit type listed as universal for Mercury/Mariner outboard applications, it is a practical replacement part to keep on hand for outboard maintenance and repair work.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0645
• Category: Mercury Outboard Gasket
• Material: OEM
• Color: White
• Shape: Round
• Fit Type: Universal Fit for Mercury/Mariner outboard motors
• Weight: 0.07 pounds
• UPC: 808282242831

Fitment

• Mercury/Mariner outboard motors (universal fit)

Frequently Asked Questions

What is the Sierra 18-0645 gasket used for? It is an adapter plate gasket that seals the adapter plate joint on Mercury and Mariner outboard motors, helping maintain a proper seal during engine operation.

Does the 18-0645 gasket fit all Mercury and Mariner outboards? It is listed as a universal fit for Mercury/Mariner outboard motors rather than being restricted to one specific model or year range.

What color is the 18-0645 adapter plate gasket? The gasket is white.

What shape is the Sierra 18-0645 gasket? It has a round shape, matching the adapter plate mounting pattern it is designed to seal.

How much does the 18-0645 gasket weigh? The Sierra 18-0645 adapter plate gasket weighs 0.07 pounds.

Is the Sierra 18-0645 gasket an OEM part or aftermarket? It is an aftermarket gasket manufactured to OEM specifications, meaning it is built to meet or exceed the performance of the original equipment part it replaces.

What material is the 18-0645 gasket made from? It is made to OEM material specifications for the adapter plate application on Mercury/Mariner outboard motors.

Can I install the 18-0645 gasket myself? Yes, it is designed as a direct-fit replacement for the adapter plate joint, suitable for use during a standard powerhead service or rebuild.

What is included when I order part number 18-0645? The order includes one Sierra adapter plate gasket, part number 18-0645.

Why choose the Sierra 18-0645 over a generic gasket? Sierra manufactures the 18-0645 to meet or exceed the specifications of the original equipment part, offering a dependable seal for the marine environment rather than a generic substitute.