1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 308Get this manual
Running Forward While running forward, the tilt and trim cylinders must hold the motor in the selected trim position and the following components must hold hydraulic pressure: 1The seals on the tilt and trim pistons 2The a-ring on the stem valve 3The manual release valve 4The tilt and trim check valve Running in Reverse While running in reverse, the following components must hold pressure to prevent the motor from lifting out of the water: 1The seals on the tilt piston 2The manual release valve 3The reverse lock check valve 4The tilt up relief valve Tilting or Shallow Water Drive While running in the shallow water drive mode, (under 1600 rpm) or while the motor is tilted, the following components are pressurized and must hold pressure: 1The seals on the tilttrim pistons 2The manual release valve 3The tilttrim check valve 4Tilt cylinder relief valve 5The tilt up relief valve Striking an Underwater Object When an underwater object is hit, the tilt up relief valve opens and allows the tilt cylinder to extendThe motor will be lifted and will require that you electrically tilt it down into the water Testing Procedures