1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 97Get this manual
100-115 (4 cyl (Design 2)
Body (Opposite Side View) Rubber Valve Plastic Disc Cover (Opposite Side View) Plastic Check Valve Retainer Cast Aluminum Cover Body Three Tabs Three Tabs