1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 233Get this manual
MAXIMUM TILT With the cylinder at maximum travel, and due to no ram movement, the pressure inside of the trim cylinder will increase to the pressure required to move the tilt relief actuator (i)The tilt relief actuator's "pin" opens the tilt relief valve (k)Up pressure flows into the trim relief passage, and return back into the reservoir (t)