Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 210Get this manual
Shock Function Retu rn After the engine clears the under water object, the weight of the engine will increase the oil pressure be-
tween the memory piston (e) and shock piston (d) to
the level required to open the shock return valve (v)
inside the shock piston, allowing the oil to bleed back