1991 Johnson Evinrude EI 60 Loop V Models 150, 175 outboards Service Manual, Page 271Get this manual
Tilt Relief 1If the recommended RPM is exceeded while operating the motor in the shallow water drive mode, increased pressure beneath the tilt piston opens the tilt relief valve built into the manual release valve 2Fluid flows from below the tilt piston, through the tilt relief valve
and to the reservoir
3As the tilt piston moves down, the filter valve opens and allows fluid to flow from the reservoir to the top of the tilt cylinder4The motor will tilt down to the top of the trim range