Mitsubishi S12U Operation & Maintenance Manual page 69

Table 5-3 Periodic maintenance chart for general-purpose power supply engine (3 / 5)
Service
interval
After 12000 Overhaul of top end of engine (remove the cylinder heads for inspection and main-
service tenance.)
hours or 8
years,
whichever
comes first
Cylinder
heads and
valve mech-
anisms
Safety valve
Cylinder liners
Pistons
Piston rings
Connecting rods
Crankshaft
Damper
Front gear and timing gear
Service item
Disassemble and maintain, clean and change expendable parts.
Valve seat
Inlet and
exhaust valves
Cylinder head
gasket
Copper tubes
Valve guides,
valve rotator,
valve cotter,
pushrods,
rocker arm
bushings, valve
springs, tappet
rollers, tappet
roller bushings,
tappet shafts,
tappet guides,
tappet guide
set screws.
Stem seal
Chapter 5
Service contents
Inspect, regrind and lap.
Inspect, regrind and lap.
Change.
Change copper tubes and O-rings.
Inspect.
Change.
Inspect and change expendable parts.
Inspect and clean.
Inspect including overhaul and clean.
Change.
Inspect bolts, inspect Magnaflux serrations,
change big-end bearing shells and inspect small-
end bushings.
Inspect and adjust deflection.
Analyze silicon oil properties and change thermo
label.
Inspect gear teeth.
PERIODIC MAINTENANCE CHART
Page
5-15