The Komatsu 155-4 series engine service repair manual provides comprehensive procedures for overhaul and maintenance of these Japanese-made compact diesel engines. Cylinder head service, fuel injection system calibration, cooling system diagnostics, electrical troubleshooting, and detailed part identification with exploded views throughout.
Komatsu 155-4 Series Engine Service Repair Workshop Manual
VEHICLE/EQUIPMENT INTRODUCTION:
The Komatsu 155-4 is a compact diesel engine series developed by Komatsu Ltd., the Japanese multinational corporation best known for its construction and mining equipment. The 155 series engines are liquid-cooled, four-stroke diesel powerplants designed for applications in agricultural equipment, generators, pumps, compact construction machinery, and industrial equipment. The -4 generation represents the evolved version of the 155 series with improved fuel injection timing, better emissions compliance, and enhanced low-end torque characteristics compared to earlier generations.
Komatsu has been manufacturing diesel engines for over a century, and the 155-4 series benefits from decades of engineering refinement in bore-to-stroke ratio for optimal thermal efficiency, direct injection combustion chamber design for clean fuel burn, and robust cast iron block construction that can handle the vibration and load cycles of continuous-duty applications. These engines are common in compact tractors, small generators, hydraulic power units, and material handling equipment where reliable diesel power is required without the size and weight of larger industrial diesel engines.
SERVICE & REPAIR SCOPE:
- Engine block disassembly, cylinder inspection, and bore measurement
- Cylinder head gasket replacement, head surface resurfacing specification
- Piston and ring replacement with ring gap and clearance measurement
- Fuel injection pump timing adjustment and nozzle testing
- Injector removal, bench testing, and pop-pressure calibration
- Valve clearance adjustment, valve guide wear measurement, valve seat cutting
- Water pump replacement and thermostat testing
- Oil pump inspection, oil pressure relief valve testing
- Alternator removal, diode trio testing, and brush inspection
- Starter motor solenoid and armature bench testing
- Fuel filter and air filter replacement intervals
- Camshaft timing marks alignment and drive gear wear inspection
- Wiring harness and electrical sensor diagnostics
TECHNICAL SPECIFICATIONS:
- Type: Komatsu 155-4 series liquid-cooled diesel engine
- Configuration: Inline multi-cylinder four-stroke diesel
- Aspiration: Naturally aspirated (standard variants)
- Fuel system: Direct injection
- Cooling: Liquid-cooled with radiator and thermostat
- Lubrication: Full-flow filtered pressure lubrication
- Starter: 12V electric motor with solenoid
- Alternator: Standard output with voltage regulator
- Rotation: Counterclockwise viewed from flywheel end
DIAGNOSTIC INFORMATION:
- Hard starting or long crank time: check fuel filter for contamination, bleed fuel system of air, test glow plug operation, verify injection pump timing
- Low power output: inspect air filter restriction, test injector spray pattern and pop pressure, check compression on all cylinders, verify fuel delivery volume
- Excessive white or blue exhaust smoke: test injector atomization, check valve stem seal integrity, measure cylinder bore wear, inspect turbocharger seals if equipped
- Oil pressure too low: verify gauge accuracy with mechanical test, check oil viscosity for temperature, inspect oil pump pickup screen, evaluate main and connecting rod bearing clearances
- Coolant loss without visible leak: perform combustion gas test on cooling system, check head gasket for breach, inspect cylinder head for cracks, check heater core
- Engine vibration: inspect engine mount rubber bushings, check crankshaft pulley for separation, verify fuel delivery balance between cylinders
- Overheating: clean radiator exterior, check belt tension, test thermostat opening temperature, verify coolant mixture, inspect water pump impeller
ILLUSTRATIONS & DIAGRAMS INCLUDED:
- Complete engine exploded views with all component part identification
- Cylinder head assembly with valve train and timing detail
- Fuel injection pump cross-section with delivery and advance mechanism
- Injector nozzle cutaway with spray pattern and pop pressure specs
- Cooling system flow diagram with thermostat and water pump
- Oil circuit schematic showing lubrication path from sump to all bearings
- Electrical wiring diagram with sensor connections and alternator
- Alternator and starter motor exploded assemblies
- Engine mount and installation dimensional drawings
COMPATIBILITY:
- Models: Komatsu 155-4 series diesel engine
- Covers all variants within the 155-4 engine family
- File format: Searchable PDF document
- Compatible with Windows, macOS, Linux, tablets, and smartphones
- Viewable on any PDF reader including Adobe Acrobat Reader
FILE PROPERTIES:
- Format: Searchable PDF
- Language: English
- Delivery: Instant digital download
- Access: Download anytime after purchase
Komatsu 155-4 Series Engine Service Repair Workshop Manual
VEHICLE/EQUIPMENT INTRODUCTION:
The Komatsu 155-4 is a compact diesel engine series developed by Komatsu Ltd., the Japanese multinational corporation best known for its construction and mining equipment. The 155 series engines are liquid-cooled, four-stroke diesel powerplants designed for applications in agricultural equipment, generators, pumps, compact construction machinery, and industrial equipment. The -4 generation represents the evolved version of the 155 series with improved fuel injection timing, better emissions compliance, and enhanced low-end torque characteristics compared to earlier generations.
Komatsu has been manufacturing diesel engines for over a century, and the 155-4 series benefits from decades of engineering refinement in bore-to-stroke ratio for optimal thermal efficiency, direct injection combustion chamber design for clean fuel burn, and robust cast iron block construction that can handle the vibration and load cycles of continuous-duty applications. These engines are common in compact tractors, small generators, hydraulic power units, and material handling equipment where reliable diesel power is required without the size and weight of larger industrial diesel engines.
SERVICE & REPAIR SCOPE:
- Engine block disassembly, cylinder inspection, and bore measurement
- Cylinder head gasket replacement, head surface resurfacing specification
- Piston and ring replacement with ring gap and clearance measurement
- Fuel injection pump timing adjustment and nozzle testing
- Injector removal, bench testing, and pop-pressure calibration
- Valve clearance adjustment, valve guide wear measurement, valve seat cutting
- Water pump replacement and thermostat testing
- Oil pump inspection, oil pressure relief valve testing
- Alternator removal, diode trio testing, and brush inspection
- Starter motor solenoid and armature bench testing
- Fuel filter and air filter replacement intervals
- Camshaft timing marks alignment and drive gear wear inspection
- Wiring harness and electrical sensor diagnostics
TECHNICAL SPECIFICATIONS:
- Type: Komatsu 155-4 series liquid-cooled diesel engine
- Configuration: Inline multi-cylinder four-stroke diesel
- Aspiration: Naturally aspirated (standard variants)
- Fuel system: Direct injection
- Cooling: Liquid-cooled with radiator and thermostat
- Lubrication: Full-flow filtered pressure lubrication
- Starter: 12V electric motor with solenoid
- Alternator: Standard output with voltage regulator
- Rotation: Counterclockwise viewed from flywheel end
DIAGNOSTIC INFORMATION:
- Hard starting or long crank time: check fuel filter for contamination, bleed fuel system of air, test glow plug operation, verify injection pump timing
- Low power output: inspect air filter restriction, test injector spray pattern and pop pressure, check compression on all cylinders, verify fuel delivery volume
- Excessive white or blue exhaust smoke: test injector atomization, check valve stem seal integrity, measure cylinder bore wear, inspect turbocharger seals if equipped
- Oil pressure too low: verify gauge accuracy with mechanical test, check oil viscosity for temperature, inspect oil pump pickup screen, evaluate main and connecting rod bearing clearances
- Coolant loss without visible leak: perform combustion gas test on cooling system, check head gasket for breach, inspect cylinder head for cracks, check heater core
- Engine vibration: inspect engine mount rubber bushings, check crankshaft pulley for separation, verify fuel delivery balance between cylinders
- Overheating: clean radiator exterior, check belt tension, test thermostat opening temperature, verify coolant mixture, inspect water pump impeller
ILLUSTRATIONS & DIAGRAMS INCLUDED:
- Complete engine exploded views with all component part identification
- Cylinder head assembly with valve train and timing detail
- Fuel injection pump cross-section with delivery and advance mechanism
- Injector nozzle cutaway with spray pattern and pop pressure specs
- Cooling system flow diagram with thermostat and water pump
- Oil circuit schematic showing lubrication path from sump to all bearings
- Electrical wiring diagram with sensor connections and alternator
- Alternator and starter motor exploded assemblies
- Engine mount and installation dimensional drawings
COMPATIBILITY:
- Models: Komatsu 155-4 series diesel engine
- Covers all variants within the 155-4 engine family
- File format: Searchable PDF document
- Compatible with Windows, macOS, Linux, tablets, and smartphones
- Viewable on any PDF reader including Adobe Acrobat Reader
FILE PROPERTIES:
- Format: Searchable PDF
- Language: English
- Delivery: Instant digital download
- Access: Download anytime after purchase
