Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 200Get this manual
Trim Up When the trim switch is activated in the up position, the etectric motor (a) begins to rotate the pump gears (n), the oil pump draws small amount of oil through the filter, up circuit pick-up and past the feed valve check bait (0)The oil pump gear (n) rotation forces oit into the passages for the up circuitOil, under pressure, will slide the shuUle valve (p) against the down ci rcuit pressure operated valve (h)The shuttle valve will mechanically open the down pressure operated valve, allowing oil from the down cavity of the trim cylinder, to flow into the oil pumpThis returning oil, from the down cavity, will supply most of the oil required for the up circuitOil in the up circuit is blocked from returning into the reservoir (t) by the ball inside the down circuit feed valve (m)The pressure of the oil will fmee the up circuit pressure operated valve (I) to open, allowing the oil to enter the passages inside the manifold (f) leading to the trim cylinder up cavityOil is blocked from all other passages by the closed manual tilt valve (j) and closed tilt relief valve (k)Oil under pressure will enter the trim cylinder below the memory piston (e)With an increasing amount of oil entering the cylinder, the memory piston contacts the shock piston (d) and forces the trim rod (b) up and out, raising the outboard motorOil on the top of the shock piston exits through passage running down along the side of the cylinder and enters the manifold passagesInside the manifold the oil seats the ball (r) inside the suction valve (g), closing the passage into the reservoirThe oil is drawn back into the pump (n) through the open pressure operated valve (h) and enters the pump as supply for the up circuit