Komatsu 4D84E-3D(S/N 03508-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 4D84E-3D engine powers compact excavators such as the PC40R-8 and PC45R-8. These machines operate in the 9,182 to 12,688 lb weight class. Production years span from 2017 to 2025. The engine replaces the 4D84E-3C variant. It succeeds the 4D84E-3B series. Configurations include standard and LC models. The engine delivers 84 hp at 3000 rpm.
The 4D84E-3D engine marks a shift to Tier II emissions compliance. It uses a 1.4-liter displacement. The engine features a 3-cylinder design. The 84mm bore supports high torque output. This engine matters in the used market due to its reliability. Parts availability remains strong. The engine fits multiple Komatsu models. Service intervals are standardized. The machine offers efficient fuel consumption. It is suitable for construction and utility work.
Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.
Komatsu 4D84E-3D(S/N 03508-UP) specifications
Engine
| Model | 4D84E-3D |
| Serial Range | 03508-UP |
| Emissions Tier | Stage II / Tier II |
| Power | 84 hp (61.8 kW) @ 3000 rpm |
| Cylinders | 4 |
| Displacement | Not documented for this exact serial range — verify with your dealer |
Weights
| Operating Weight | Not documented for this exact serial range — verify with your dealer |
| Shipping Weight | Not documented for this exact serial range — verify with your dealer |
| Ground Pressure | Not documented for this exact serial range — verify with your dealer |
Dimensions
| Transport Length | Not documented for this exact serial range — verify with your dealer |
| Transport Width | Not documented for this exact serial range — verify with your dealer |
| Transport Height | Not documented for this exact serial range — verify with your dealer |
| Track Gauge | Not documented for this exact serial range — verify with your dealer |
| Ground Clearance | Not documented for this exact serial range — verify with your dealer |
Performance
| Travel Speed | Not documented for this exact serial range — verify with your dealer |
| Gradeability | Not documented for this exact serial range — verify with your dealer |
Service capacities (summary)
| Fuel Tank | Not documented for this exact serial range — verify with your dealer |
| Hydraulic System | Not documented for this exact serial range — verify with your dealer |
| Engine Oil | Not documented for this exact serial range — verify with your dealer |
| Cooling System | Not documented for this exact serial range — verify with your dealer |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
Komatsu 4D84E-3D(S/N 03508-UP) maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the 4D84E-3D(S/N 03508-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Monitor KOWA oil samples at 500-hour intervals. Check coolant SCA levels regularly. Inspect hydraulic oil for contamination. Track fuel dilution in engine oil. Analyze wear metals in hydraulic fluid. Test battery load capacity. Monitor turbocharger health. Check air filter restriction. Inspect belts and hoses for wear. Verify fluid levels daily. Track undercarriage wear. Inspect structural components.
Corrective & Common Repairs
Replace fuel injectors if power drops. Fix coolant leaks at the water pump. Replace hydraulic return filters. Service the battery terminals. Check the EPC solenoid valve. Inspect the LS-EPC solenoid valve. Check the EPC safety switch. Inspect the main solenoid valve. Check the ambient pressure sensor. Inspect the intake air temperature sensor. Check the coolant temperature sensor. Inspect the engine controller power.
Overhaul & Rebuild Points
Rebuild the engine at 10,000 hours. Replace cylinder kits. Install new piston rings. Replace valve seats. Inspect the crankshaft. Check the camshaft. Replace the oil pump. Replace the water pump. Inspect the turbocharger. Check the fuel injection pump. Inspect the governor. Check the cooling system.
Seasonal & Environment Servicing
Check DEF levels in cold weather. Inspect the battery in extreme heat. Check the coolant concentration. Inspect the air filter in dusty conditions. Check the hydraulic hoses in cold weather. Inspect the undercarriage in muddy conditions. Check the structural components in rocky conditions. Inspect the turbocharger in high-altitude conditions. Check the fuel system in humid conditions. Inspect the electrical system in wet conditions. Check the engine controller in extreme temperatures. Inspect the cooling system in hot weather.
4D84E-3D(S/N 03508-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM129100-55650 | Element,Fuel Filter | Fuel system service | Check fitment → |
| YM129612-55620 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| (YM129612-55620) | Fuel Filter Ass'Y,(See Fig.A4110-B0a2a) | Fuel system service | Check fitment → |
| YM119808-12520 | Element,Outer | Scheduled service item | Check fitment → |
| YM129051-12530 | Element,Inner | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
4D84E-3D(S/N 03508-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor failure | Broken sensor, wiring issue, or connector corrosion | Replace the speed sensor and verify voltage at the pin connector |
| CA451 | Common rail pressure sensor feedback value too high | Malfunction in the rail sensor or actual overpressure condition | Diagnose the fuel rail pressure sensor or pump lines |
| CA111 | Internal engine controller fault | ECM hardware or software failure | Replace or reprogram the ECM |
| CA122 | Intake air pressure high voltage | Sensor malfunction or wiring issue | Verify the intake pressure sensor and wiring |
| CA123 | Intake air pressure low voltage | Sensor short or airflow restriction | Check for a sensor short or an airflow restriction |
| CA441 | Battery voltage too low | Weak battery or charging system failure | Replace the alternator or battery; check the voltage regulator |
| CA442 | Battery voltage too high | Alternator overcharging or regulator failure | Replace the alternator or battery; check the voltage regulator |
| CA234 | Engine overspeed | Throttle calibration error, engine load cycle issue, or operator misuse | Verify throttle calibration, engine load cycle, or operator misuse |
| CA153 | Intake air temperature sensor feedback voltage too high | Sensor failure or circuit fault | Replace or test the IAT sensor |
| CA154 | Intake air temperature sensor feedback voltage too low | Sensor failure or circuit fault | Replace or test the IAT sensor |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
4D84E-3D(S/N 03508-UP) attachments & work tools
Mini Excavator Work Tools
Typical bucket widths for this engine class range from 300 mm to 600 mm. Coupler systems include quick-attach plates and pin-on mounts. Hydraulic flow requirements vary by configuration/series.
Skid Steer Loader Attachments
Compatible tools include buckets, grapples, and augers for compact loaders. Mounting systems utilize standard skid-steer quick-attach interfaces. Hydraulic kit arrangements depend on the specific tool's flow and pressure needs.
Engine Guarding and Protection
Factory configurations include engine guards and protective covers. These options safeguard the 4D84E-3D engine from debris and impact. Guarding details are specified in the equipment operation and maintenance manual.
All 4D84E-3D(S/N 03508-UP) assemblies by section
Every catalogued assembly group for the Komatsu 4D84E-3D(S/N 03508-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Engine
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Air Cleaner And Mounting (Double Element)
| YM***90 | Gasket,(Not Shown) | 1 |
| YM***60 | Support | 1 |
| YM***10 | Case, Assembly | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Air Cleaner And Mounting (Single Element)
| YM***90 | Gasket,(Not Shown) | 1 |
| YM***60 | Support | 1 |
| YM***00 | Air Cleaner Ass'Y | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Air Intake Manifold And Connection
| YM***02 | Bolt Plated | 6 |
| YM***02 | Screw | 2 |
| YM***00 | Heater,Intake Air | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Alternator (40a) (Inner Parts)
| YM***50 | Brush Ass'Y | 1 |
| YM***00 | Retainer,Bearing | 1 |
| YM***70 | Diode Ass'Y | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Alternator And Mounting (40a)
| YM***00 | Adjuster, Belt | 1 |
| YM***02 | Nut | 1 |
| YM***02 | Screw | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Camshaft And Tappet
| YM***80 | Camshaft Ass'Y | 1 |
| YM***01 | Gear Ass'Y,Camshaft | 1 |
| YM***50 | Bearing, Thrust | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Crankshaft
| YM***00 | Gear,Crank | 1 |
| YM***80 | Parallel Pin | 1 |
| YM***50 | Pulley,Crank | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Cylinder Block
| YM***60 | Cylinder Block, Assembly | 1 |
| YM***00 | Plug | 1 |
| YM***50 | Plug | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Cylinder Block Accsessory
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***20 | Plug,Drain(Without Oil Cooler Type) | 1 |
| YM***10 | Guide,Level Gauge | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Cylinder Head
| YM***80 | Retainer, Spring | 8 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***10 | Valve,Exhaust | 4 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Cylinder Head Cover
| YM***20 | Cover, Breather | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***90 | Retainer | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Drive Gear
| YM***02 | Nut | 1 |
| YM***01 | Idler Gear Ass'Y,Idler | 1 |
| YM***00 | Gear,Injection Pump | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Electrical Parts (Forwerded Individually Parts)
| YM***20 | Timer,Solenoid | 1 |
| YM***10 | Relay,Stop Solenoid | 1 |
| YM***00 | Relay, Safety | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Exhaust Manifold
| YM***02 | Screw | 6 |
| YM***00 | Manifold, Exhaust | 1 |
| YM***10 | Gasket (Kit) | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Flywheel And Flywheel Housing
| YM***02 | Screw | 6 |
| YM***02 | Screw | 4 |
| YM***90 | Flywheel Ass'Y | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Front Cover(#03508-05144)
| YM***02 | Bolt Plated | 2 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Front Cover(#05145-)
| YM***02 | Bolt Plated | 2 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Front Hanger
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Filter
| YM***10 | Cup, Strainer | 1 |
| YM***00 | O-Ring (Kit) | 1 |
| YM***70 | Lever | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Filter And Piping
| YM***70 | Union | 1 |
| YM***02 | Bolt Plated | 2 |
| YM***51 | Check Valve Ass'Y,Joint | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)
| YM***40 | Lever,Control | 1 |
| YM***30 | Spacer,Lever Shaft | 1 |
| YM***02 | Nut | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)
| YM***01 | Weight Assembly., Governor | 1 |
| YM***50 | Angleich Ass'Y | 1 |
| YM***00 | Washer,Spring | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)
| YM***50 | Kit, Shim | 1 |
| YM***10 | Plate? Caution | 1 |
| YM***90 | Key,Woodruff | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)
| YM***70 | Retainer, Spring | 4 |
| YM***00 | Rack,Control | 1 |
| YM***02 | Screw | 2 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Injection Pump And Piping
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***41 | Pipe,No.4 | 1 |
| YM***02 | Nut | 3 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Fuel Nozzle And Spill Hose
| YM***00 | Nozzle, Assembly | 1 |
| YM***20 | Spring | 1 |
| YM***00 | Fuel Injection Nozzle, Assembly | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Gasket Kit
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***20 | Gasket,Water Pump | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Lubricating Oil Pump
| YM***50 | Pipe,Oil | 1 |
| YM***02 | Seal,Ring (Kit) | 2 |
| YM***41 | Gasket (Kit) | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Muffler And Mounting
| YM***22 | Stud | 4 |
| YM***01 | Gasket (Kit) | 1 |
| YM***02 | Screw | 3 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Oil Filter
| YM***50 | Nut | 1 |
| YM***00 | Valve,Relief | 1 |
| YM***02 | Bolt Plated | 3 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Oil Pan
| YM***30 | Spacer | 1 |
| YM***52 | Screw | 2 |
| YM***52 | Screw | 24 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Piston And Connecting Rod
| YM***00 | Screw | 2 |
| YM***00 | Crank Pin Metal A. (Std) | 1 |
| YM***01 | Assembly, Piston (+0.25 mm) | 4 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Rear Hanger
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Rocker Arm
| YM***02 | Nut,Rock | 3 |
| YM***02 | Screw | 7 |
| YM***80 | Spring | 4 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Starting Motor (Inner Parts)
| YM***80 | Housing | 1 |
| YM***90 | Clutch, Starter | 1 |
| YM***30 | Bolt | 2 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Starting Motor And Mounting
| YM***52 | Bolt Plated | 2 |
| YM***02 | Nut,Rock | 1 |
| YM***00 | Washer,Spring | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Pulley Dia 130mm)
| YM***40 | Joint | 1 |
| YM***02 | Bolt Plated | 2 |
| YM***20 | Gasket,Water Pump | 1 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Pulley Dia 90mm)(#05483-)
| YM***40 | Joint | 1 |
| YM***90 | V-Belt | 1 |
| YM***02 | Bolt Plated | 2 |
Komatsu : 4d84e-3d(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Pulley Dia 96mm)
| YM***40 | Joint | 1 |
| YM***90 | V-Belt | 1 |
| YM***02 | Bolt Plated | 2 |
4D84E-3D(S/N 03508-UP) serial number reference
The engine identification plate is riveted to the engine block, typically on the left side near the injection pump. Read the prefix as the first alphanumeric sequence on the plate (e.g., 4D84E-3D), followed by the serial number starting at 03508 for this specific generation.
| Prefix | Identifies | Notes |
|---|---|---|
| 4D84E-3D | Engine Model | Komatsu 4D84E-3D engine. Serial range 03508-UP. Factory parts catalog confirms this designation for the specified serial break. Varies by configuration/series for earlier 4D84E-3B/3C variants. |
Frequently asked questions
What engine does the Komatsu 4D84E-3D use?
The Komatsu 4D84E-3D is a 1.4-liter, 3-cylinder, water-cooled diesel engine. It delivers 84 hp at 3000 rpm. It meets Tier II emissions standards. The engine features an 84mm bore. It is used in the PC40R-8 and PC45R-8 excavators.
What is the operating weight of the machine?
The operating weight varies by configuration. It ranges from 9,182 lb to 12,688 lb. The weight depends on the model and attachment package. The PC40R-8 and PC45R-8 models fall within this range. The weight affects transport planning and jobsite fit.
What replaced the Komatsu 4D84E-3D?
The 4D84E-3D succeeded the 4D84E-3C variant. It replaced the 4D84E-3B series. The engine is part of the 68E-88E series. It is used in the PC40R-8 and PC45R-8 excavators. The engine is still in production as of 2025.
What 4D84E-3D(S/N 03508-UP) owners discuss
What is the net horsepower rating for the Komatsu 4D84E-3D engine?
What are the common hydraulic behaviors and failure patterns associated with Komatsu excavators using this engine platform?
What undercarriage and wear patterns are typical for machines in this class?
What are the known engine quirks and maintenance requirements for the 4D84E-3D series?
What are the common electrical and sensor issues reported for this engine platform?
What specific items should be checked when buying a used machine with the 4D84E-3D (S/N 03508-UP) engine?
What safety-critical fixes require dealer verification for this engine?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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