Yanmar 3YM30 Sevice Manual page 99

(17)Removing the rocker arm shaft assembly
1) Loosen the hexagon head bolts and remove the
rocker arm cover.
Note:
Don't loosen the cross-recessed-head bolts on the
rocker arm cover, when removing the rocker arm
cover.
2) Remove the bolts(s) for the rocker arm shaft
support, and remove the entire rocker arm shaft
assembly.
3) Pull out the push rods.
(18)Removing the cylinder head
1) Loosen the cylinder head bolts with a torque wrench, and remove the cylinder head.
2) Remove the cylinder head gasket.
(19)Removing the marine gearbox
Loosen the bolts for the clutch case flange, and remove the gearbox assembly.
(20)Removing the flywheel
Loosen the flywheel bolts and remove the flywheel.
Note:
Be careful not to scratch the ring gear.
4. Disassembly and reassembly
Don't disassemble
the cross-recessed-hand bolts.
Bolt
(Removing flywheel)
84
Flywheel
Flywheel housing