IO-390-D Series Engine Maintenance Manual
72-30
© 2020 Avco Corporation. All Rights Reserved
Page 206
March 2020
IO-390-D Series Engine Maintenance Manual
E.
Remove the screws from the rocker box cover (Figure 15).
NOTICE: A s
ilicone rocker box cover gasket can be reused if it is not damaged.
F.
Remove the rocker box cover and gasket. Discard the gasket.
G.
Remove the nuts and lock washers from the rocker shaft covers. Discard the lock washers.
H.
Remove the rocker shaft cover, and rocker shaft cover gasket. Discard the gasket.
Figure 15
IO-390-D Series Engine Valve Components
I.
Turn the crankshaft to put the piston at TDC of the compression stroke of the cylinder to be
removed. (With the piston in this position, both intake and exhaust valves are closed and the
piston is extended away from the crankcase to prevent damage when the cylinder is
removed.)
NOTICE:
There is a different rocker assembly (Figure 15) for the intake and exhaust side of
the engine cylinder. Identify whether the rocker assembly is from the intake or
exhaust side for reference on cylinder assembly.
Do not remove the valve rocker shaft until the cylinder is removed from the engine.
