Volvo Penta D25A MS, Operator'S Manual

Page: 37 / 87

37
Maintenance schedule
Top overhaul
Dependent of your application, working conditions and service level a “top overhaul” might be required
in case of:
Gas leakage through valves
Too much valve clearance
Low compression pressure
Top overhaul includes:
Remove cylinder heads and check liners and com-
bustion chambers of pistons
Disassemble cylinder heads
Check inlet and exhaust valves, check valve seats
(lap if necessary)
Check piston top
Check cylinder liner
Check instruments, alarms and shutdown functions
Check pipe clamp contact
Change fresh water pump seals
Change sea water pump seals
Overhaul turbo charger
Check vibration damper on burrs and leaks
Check exhaust pipe joints
Check governor control linkage
Overhaul information
1
st
major overhaul
Dependent of your application, working conditions and service level a “major overhaul” might be requi-
red in case of:
Decreased power output
Increased fuel consumption
Increased lubrication oil consumption
Increased blow-by gases
Gas leakage through valves
Starting problems
Increased noise from engine parts
Abnormal color of exhaust gases from warm engine
Major parts:
Inlet and exhaust valve seats
Inlet and exhaust valves
Valve rotators
Valve cotters
Rocker arm adjusting screws
Valve push rods
Bridge caps
Camshaft bushings
Camshaft expansion plugs
Lubrication oil pump
Main bearings
Cylinder liners
Main bearing cap bolts and washers
Piston rings
Connecting rod bearings
Vibration damper
Air duct rubber hoses
Cooling water rubber hoses
Consumable items (gaskets, oil seals, o-rings, etc.)
Change the torsional vibration damper
Major overhaul includes:
Disassemble engine, clean, check and change major parts.
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