90404-ZV5-003 Rr Washer - Overview. The 90404-ZV5-003 Rr Washer is a critical component in Honda marine engine systems, functioning as a rear washer designed to provide proper spacing and a sealing surface between mechanical parts. This washer supports the rigging and related marine hardware system, helping maintain the structural and operational integrity of your engine assembly. By ensuring precise fit and placement, it contributes directly to the seamless function and reliability of Honda mar