Genuine Mercury 25-30224 (1.859 x .139) O-Ring
For Mercrusier MCM and MIE GM based V6 and V8 thermostat housings with flat cover plate
Also found on Mercury outboards below water pump base
Replaces - 18-7173-9, 82250, 310327, 9-76501 and 30224Q
Superseded by - 8M0204651
