Yamaha Marine Outboards F4A/F4 Factory Service Manual, Page 82Get this manual
INSP ADJ
LOWER UNITGENERAL
8 Apply the specified pressure
Pressure: 100 kPa (1.0 kgcm2, 14.2 psi) Check that the lower unit holes the specified pressure for ten secondsNOTE: Do not over-pressurerize the lower unitExcessive pressure may cause the air to leak out1
GENERAL
Anode 1Inspect:
9Anode (engine) 9Anode (lower unit)
Scales CleanOilGrease CleanWear (12)Damage Replace