23173-ZW5-000 Mount Case Seal Rub - Overview. The 23173-ZW5-000 Mount Case Seal Rub is an essential component in Honda marine engine systems designed to provide a durable, high-quality rubber seal that effectively protects and cushions the gear case. This part serves a vital role in ensuring that water does not penetrate the internal mechanics, which helps maintain smooth operation and extends engine life. Meticulously crafted to fit precisely within the mount case system, it ensures seamless in