1977 Johnson 2HP Outboards Service Manual, Page 47Get this manual
6-5 GEARCASE PRESSURE test gearcase sealing, proceed as follows1Remove drain plug and screw in pressure test gauge6-13Stevens Experimental pressure test gauge illustrated2Figure
pressure to 3-6 pounds (21-41 kPa)Gearcase must hole 3-6 pounds (21-41 kPa) If pressure gauge indicates leakage, submerge gearcase in water to determine source of leakage as evidenced bubblesIf gearcase pressure gauge does not indicate leakage, increase pressure to 16-18 pounds (110-124 kPa)Pressure should also hold at 16-18 pounds (110-124 kPa)If pressure does not hold, submerge gearcase in water and check for source of leakageMake necessary repairs and repeat testGearcase must hold within the range of 3-6 pounds (21-41 kPa) pressurepressure' 131
REASSEMBLY AND INSTALLATION OF EXHAUST HOUSING
If removed install vibration dampeners
Figure 6-13Gearcase Pressure Test