23172-Zz3-003 Mount Case Gasket - Overview. The 23172-ZZ3-003 Mount Case Gasket is a vital sealing component for Honda marine engine systems. It supports the marine engine case system by providing a secure and watertight seal, which prevents leaks and protects sensitive internal components from water intrusion and contaminants. Designed to exact factory specifications, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Precise gask