1998 Johnson Evinrude "EC" Accessories Service Manual, P/N 520213, Page 157Get this manual
Description of Power Steering System
The pump and reservoir assembly supplies fluid, under pressure, to the spool valve housing and steering cylinder
A gerotor pump, driven at approximately 1.4 times flywheel speed, pressurizes the fluid and directs it to the steering cylinderThe reservoir should be filled with avIC Power TrimlTilt and Power Steering Fluid or GM Dexron I fluid
The steering cylinder assembly controls steering assist and directionUsing the mechanical input from the boat's steering system, the spool valve directs pressurized fluid to the correct side of the steering cylinder piston