Mercury Mariner 30/40 4-Stroke Outboard Service Manual 1998, Page 479Get this manual
BIGFOOT GEAR HOUSING
2Pressu rized housing to 10 to 12 psi (69-83 kPa) and observe gauge for minutes3Rotate drive shaft, prop shaft and move shift shaft while housing is pressurized to check for leaks
4If pressure drop is noted, immerse housing in water5Re-pressurize to 10 to 12 psi (69-83 kPa) and check for ai bubbles6Replace leaking seals as necessaryRetest housingNOTE: Gearcase should hold 10 to 12 psi (69-83 kPa) for minutes
7Remove tester from housing and install vent plug
Filling Gear Housing With Lubricant
NOTE: Gear housing lubricant capacity is 22.5 fI oz (665.2 ml)
installed on engine, to leads from