1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Repair Manual P/N: 507616, Page 220Get this manual
Quality of the image is intentionally reduced!
27 Pressure and vacuum test the gearcase as follows :
Remove the filldrain plug and screw in gauge
pressure test
Pump pressure up to 3-6 psi (21-42 kPa)If pressure gaug