Yamaha - Water Check Plug Cooling System Component 6L8-F8193-00-00. Overview. It's a small part, but this is one of those pieces you don't want to overlook. The water check plug plays a role in monitoring and maintaining proper cooling flow, and when it's worn or leaking, it can throw things off more than you'd expect. I've seen engines run hotter than they should just because of a bad seal here. Swapping it out is quick, but it keeps your cooling system doing its job right.. Key Features. Cooling System Access Point - Allows for proper inspection and monitoring of water flow.. Secure Sealing Design - Helps prevent leaks that can affect cooling performance.. Corrosion-Resistant Construction - Built to handle exposure to saltwater and marine environments.. Factory-Spec Fitment - Matches Yamaha components for proper installation and reliable sealing.. Simple Replacement Part - Easy to install with minimal tools and downtime.. Engine & Boat Compatibility. Designed for Yamaha outboard engi