1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 312Get this manual
1To install gauges remove the manual release valveTo remove the valve: abUsing the trim switch, run the unit down completelyLoosen the manual release valve one full turn cMomentarily jog the trim switch "up," then "down," then "up"Failure to follow step below could result in eye injury to you or bystanderdSome residual pressure may be present in the hydraulic system when the manual release valve is removedRemove the manual release valve watching for residual pressure tending to push valve outAlways pack shop rag or towel around the screwdriver shank and against the manual release valve access hole when removing the manual release valveThis will trap squirting fluid as the manual release valve is removedCatch lost oil with rag and drip pan