Mitsubishi S12U Operation & Maintenance Manual page 61

Table 5-1 Periodic maintenance chart for engine in regular use (5 / 5)
Service
interval
Every 24000 Major overhaul (complete disassembly and inspection)
service Change all O-rings, gaskets and seals.
hours
Cylinder
heads and
valve mech-
anisms
Cylinder liners
Main bearings
Cam bushings
Pistons
Connecting rods
Crankshaft
Damper
Spring coupling
Timing gear
and front
gear
Fuel system
Lubricating
system
Cooling
system
Inlet and
exhaust
systems
Governor
Service item
Change inlet and exhaust valves, valve seats, valve guides, valve
rotators and valve cotters.
Inspect and change pushrods, rocker arm bushings, valve springs,
tappet rollers, tappet roller bushings, tappet shafts, tappet guides
and tappet guide set screws.
All shafts
Rear idler gear
Change front idler bearing, camshaft roller bearing, front seal, rear
seal, front gear case gasket and rear gear case gasket.
Fuel injection
nozzles
Fuel injection
pump
Fuel feed pump
(trochoid type)
Regulator valve
Oil pump
Oil thermostat
Oil pan
Engine oil regu-
lator valve
Water pump
Coolant ther-
mostat
Air cooler
Exhaust pipes
Exhaust duct
Actuator
Governor case
Control shaft
Chapter 5
Service contents
Change.
Inspect caps and bolts, and change main bear-
ings.
Inspect and change (in 2nd 24000-service-hour-
interval inspection and maintenance).
Disassemble and inspect piston crown, and
change O-rings.
Change bolts and small-end bushings.
Inspect journals and pins, and change slingers.
Change (in 2nd 24000-service-hour-interval
inspection and maintenance).
Disassemble and maintain (by spring coupling
manufacturer).
Inspect.
Inspect and change assemblies (including bush-
ings).
Change nozzle holder assemblies.
Change plunger assembly and delivery valve.
Change pump assembly.
Change.
Change safety valve and spring.
Change.
Clean and change gasket.
Inspect and change.
Change shaft and impeller.
Change.
Change element (in 2nd 24000-hour-interval
inspection and maintenance).
Inspect and change bellows.
Change seal rings.
Disassemble and maintain (by governor manu-
facturer).
Change bearings, O-rings and gaskets.
Change oil seals.
PERIODIC MAINTENANCE CHART
Page
5-7