23172-ZY9-003 Mount Case Gasket - Overview. The 23172-ZY9-003 Mount Case Gasket is a crucial sealing component supporting the oil case mounting system in Honda marine engine systems. This gasket plays a vital role in ensuring a watertight seal between the mounting case and adjacent engine parts, preventing leaks and maintaining engine integrity. Manufactured to exact factory specifications, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key