Honda Outboards BF40A/BF50A Service Manual, Page 425Get this manual
BF40A-BF50A MOTOR INSTALLATION 1) Install the drive joint in the position of the gear pump assembly as shown [1] DRIVE JOINT
[2] GEAR PUMP ASSEMBLY
2) Apply ATF to new O-ring, and install it on the power trimtilt motor assembly3) Fill the gear pump chamber with the fresh ATF up to the upper edge of the chamberIf ATF in the valve body contains air bubbles, remove the air bubbles using an oil bottle or equivalent tool Do not pour ATF into the valve body gear pump chamber quicklyPour the fluid slowly Trapped air in the system causes faulty operationRemove the air bubbles in the fluid completely