Yamaha - Anode Grommet Corrosion Protection 66M-11328-00-00. Overview. The Yamaha 66M-11328-00-00 Anode Grommet is a small but essential component used to properly secure and insulate the engine's sacrificial anode. This rubber grommet ensures the anode mounts correctly within the engine block while maintaining proper contact points needed for corrosion protection. In marine environments, sacrificial anodes protect internal engine components from galvanic corrosion caused by saltwater and electr