Komatsu 3D84E-3G(S/N 05993-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 3D84E-3G engine (S/N 05993-UP) is a vertical, water-cooled, 4-stroke, 3-cylinder diesel powerplant manufactured by Komatsu since 2017. With a displacement of 1,496 cc and a bore of 84 mm, it delivers approximately 38 hp at 2,700 rpm. This engine is primarily integrated into compact construction machinery, including the PC30MR-2 series mini excavators and SK05J-2 skid steer loaders. It succeeds earlier iterations in the 3D84E series and serves as a reliable, compact power source for equipment operating in tight spaces and light-to-medium duty cycles.
Across the 3D84E series generations, the engine has maintained its core 3-cylinder architecture while adapting to evolving emissions standards and operational demands. The 3G variant, identified by serial number 05993 and above, represents a specific production block within this lineage. In the used and parts market, the 3D84E-3G remains significant due to its widespread use in high-volume compact equipment. Its modular design and compatibility with major overhaul kits for the broader 3D84E family ensure continued availability of rebuild components, making it a staple for fleet maintenance and independent repair operations.
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 3D84E-3G(S/N 05993-UP) specifications
Engine
| Model | 3D84E-3G |
| Configuration | Vertical, water-cooled, 4-stroke, 3-cylinder diesel engine |
| Displacement | 1.496 L (91.3 cu in) |
| Bore x Stroke | 84 x 90 mm (3.31 x 3.54 in) |
| Gross Power | 38 hp (28.3 kW) @ 2,700 rpm |
| Emissions Tier | 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 |
| Dig Depth | 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 3D84E-3G(S/N 05993-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 3D84E-3G(S/N 05993-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Komatsu Oil Wear Analysis (KOWA) at every major service interval to monitor engine wear metals, coolant contamination, and fuel dilution. Check the air filter restriction indicator daily; replace the outer element at 1,000 hours or when clogged. Monitor hydraulic oil particle count and viscosity during 500-hour sampling to detect pump or valve wear early. Verify coolant SCA concentration levels at 500 hours to prevent liner cavitation and corrosion within the 3D84E-3G cylinder block.
Corrective & Common Repairs
Address fuel system issues by draining the water separator daily and replacing the fuel filter at 500 hours to protect the injection pump. Inspect the turbocharger for shaft play and seal leaks during the 1,000-hour service. Check belt tension and hose clamps for degradation, replacing worn components at 2,000 hours. Verify battery terminal integrity and alternator output during the 500-hour service to prevent electrical failures in the engine control circuit.
Overhaul & Rebuild Points
Plan for major engine overhaul when wear metal trends in KOWA reports indicate bearing or cylinder liner degradation. Replace piston rings and liners during a full rebuild to restore compression and power output. Inspect the cylinder head gasket and valve seats for leakage or burning. Use a comprehensive overhaul kit compatible with the 3D84E-3G to replace main bearings, rod bearings, and thrust washers, ensuring proper clearances for the 1,496 cc displacement.
Seasonal & Environment Servicing
In cold climates, verify coolant freeze protection and use appropriate grade diesel engine oil to ensure cold-start reliability. In dusty environments, inspect the air cleaner element more frequently and clean the radiator and oil cooler fins daily to prevent overheating. Check track tension and undercarriage components regularly on excavators to compensate for abrasive wear. Drain the fuel water separator more often in humid conditions to prevent microbial growth and injector corrosion.
3D84E-3G(S/N 05993-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM129100-55650 | Element,Fuel Filter | Fuel system service | Check fitment → |
| YM129052-55620 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| (YM129052-55620) | Fuel Filter Ass'Y,(See Fig.A4110-B0a6) | Fuel system service | Check fitment → |
| YM119640-92750 | Wrench,Oil Filter? (Pc38uu) | Lubrication service | Check fitment → |
| YM121120-12900 | Element | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
3D84E-3G(S/N 05993-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor failure | Faulty sensor, broken wiring, or corroded connector | Replace the speed sensor and verify voltage at the pin connector |
| CA111 | Internal engine controller fault | ECM hardware failure or corruption | Replace or reprogram the ECM |
| CA441 | Battery voltage too low | Weak battery, poor connections, or alternator failure | Replace the alternator or battery; check the voltage regulator |
| CA442 | Battery voltage too high | Alternator regulator failure | Replace the alternator or battery; check the voltage regulator |
| CA122 | Intake air pressure sensor high voltage | Sensor malfunction or wiring issue | Verify the intake pressure sensor and wiring |
| CA123 | Intake air pressure sensor low voltage | Sensor short or airflow restriction | Check for a sensor short or an airflow restriction |
| 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 |
| CA234 | Engine overspeed | Throttle calibration error, engine load cycle issue, or operator misuse | Verify throttle calibration, engine load cycle, or operator misuse |
| AA10NX | Air cleaner clogging | Dirty or blocked air filter element | Replace the air filter |
| CA2311 | IMV solenoid valve failure | Faulty IMV solenoid or wire harness issue | Replace the IMV solenoid or inspect the wire harness |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
3D84E-3G(S/N 05993-UP) attachments & work tools
Excavator Buckets
Standard and heavy-duty digging buckets are the primary work tools for this engine class, typically ranging from 0.02 to 0.05 cubic meters (0.03 to 0.07 cubic yards). These tools require standard hydraulic circuit connections for boom and stick actuation.
Trenching Buckets
Narrow-width trenching buckets are offered for utility work, with widths varying by configuration but generally under 600 mm (24 inches). These tools utilize the same standard quick-coupler mounting interface as standard buckets.
Skid Steer Attachments
When mounted in skid steer loader applications, the engine supports standard skid steer quick-attach couplers for buckets, grapples, and augers. Hydraulic flow requirements for auxiliary circuits vary by the specific loader model configuration.
Hydraulic Breakers
Compact hydraulic breakers are compatible with this engine class when paired with the appropriate high-flow hydraulic kit. Mounting brackets and hose assemblies are model-specific and must be verified against the machine's serial number.
Hydraulic Hammers
Light-duty hydraulic hammers can be utilized with this power unit provided the machine is equipped with the correct pressure and flow settings. Factory guarding options may be required for high-vibration applications.
Augers
Hydraulic drive augers are available for drilling applications, with diameter capacities varying by the specific loader or excavator frame. These tools require a dedicated hydraulic circuit with a flow control valve.
Cold Planers
Small-diameter cold planer drums are compatible with skid steer configurations using this engine. The machine must have sufficient hydraulic flow and pressure ratings to drive the cutting drum motor.
Grapples
Root and material grapples are offered for skid steer and mini-excavator platforms. These tools require dual hydraulic circuits for independent tilt and rotation functions.
Forks
Pallet forks and timber forks are standard attachments for material handling tasks. These tools typically do not require auxiliary hydraulic circuits, relying solely on the machine's lift and tilt functions.
Coupler Systems
Standard quick-coupler systems are used for bucket and tool interchangeability. The specific coupler type and mounting dimensions vary by the machine model and generation.
Hydraulic Kits
Auxiliary hydraulic kits are required for tools such as breakers, augers, and grapples. Kit configurations and hose lengths vary by machine model and serial number.
Factory Guarding
Factory-installed guarding options are available for the engine compartment and hydraulic lines. These options protect against debris and impact damage in demanding work environments.
Engine Specifications
The Komatsu 3D84E-3G engine is a vertical, water-cooled, 4-stroke, 3-cylinder diesel engine. It has a displacement of 1.496 liters and produces 38 hp at 2,700 rpm.
All 3D84E-3G(S/N 05993-UP) assemblies by section
Every catalogued assembly group for the Komatsu 3D84E-3G(S/N 05993-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Engine
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Air Cleaner And Mounting
| YM***60 | Bolt,Wing | 1 |
| YM***70 | Seat,Rubber | 2 |
| YM***03 | Seal,Seal | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Air Intake Manifold And Connection
| YM***01 | Heater,Intake Air | 1 |
| YM***00 | Manifold,Air Intake | 1 |
| YM***52 | Screw | 4 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Alternator (40a) (Inner Parts)
| YM***50 | Brush Ass'Y | 1 |
| YM***00 | Retainer,Bearing | 1 |
| YM***70 | Diode Ass'Y | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Alternator And Mounting (40a)
| YM***02 | Nut | 1 |
| YM***20 | Adjuster, Belt | 1 |
| YM***02 | Screw | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Camshaft And Tappet
| YM***80 | Camshaft Ass'Y | 1 |
| YM***01 | Gear Ass'Y,Camshaft | 1 |
| YM***50 | Bearing, Thrust | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Crankshaft
| YM***00 | Gear,Crank | 1 |
| YM***80 | Parallel Pin | 1 |
| YM***10 | Spring Pin | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Cylinder Block
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Cylinder Block Accessory
| YM***00 | O-Ring (Kit) | 1 |
| YM***20 | Plug,Drain(Without Oil Cooler Type) | 1 |
| YM***00 | Gauge,Oil Level | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Cylinder Head
| YM***31 | Gasket,Head (Kit) | 1 |
| YM***80 | Retainer, Spring | 6 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Cylinder Head Cover
| YM***20 | Cover, Breather | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Drive Gear
| YM***02 | Nut | 1 |
| YM***01 | Idler Gear Ass'Y,Idler | 1 |
| YM***00 | Gear,Injection Pump | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Electrical Parts (Forwerded Individually Parts)
| YM***00 | Diode | 1 |
| YM***00 | Relay, Safety | 1 |
| YM***20 | Timer,Ribbon Heater | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Engine Stop Motor
| YM***20 | Motor Ass'Y,Engine Stop | 1 |
| YM***80 | Ring,Snap | 1 |
| YM***00 | Pin,Cotter | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Exhaust Manifold
| YM***10 | Manifold, Exhaust | 1 |
| YM***02 | Stud | 2 |
| YM***02 | Screw | 4 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Flywheel And Flywheel Housing
| YM***02 | Screw | 6 |
| YM***02 | Screw | 4 |
| YM***80 | Parallel Pin | 4 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Front Cover
| YM***90 | Front Cover Ass'Y | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Front Hanger
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Filter
| YM***00 | O-Ring (Kit) | 1 |
| YM***70 | Lever | 1 |
| YM***80 | Cup, Strainer | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Filter And Piping
| YM***70 | Union | 1 |
| YM***00 | Hose | 1 |
| YM***51 | Check Valve Ass'Y,Joint | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)
| YM***02 | Lever Ass'Y,Stop | 1 |
| YM***10 | Pin,Stop Lever | 1 |
| YM***00 | O-Ring (Kit) | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)
| YM***01 | Weight Assembly., Governor | 1 |
| YM***90 | Shaft,Governor Lever | 1 |
| YM***50 | Angleich Ass'Y | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)
| YM***50 | Kit, Shim | 1 |
| YM***10 | Plate? Caution | 1 |
| YM***50 | Cover,Side | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)
| YM***70 | Retainer, Spring | 3 |
| YM***02 | Screw | 2 |
| YM***00 | Valve,Delivery | 3 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Injection Pump And Piping
| YM***20 | Retainer, Pipe | 1 |
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***22 | Pipe,Injection? No.2 | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Fuel Nozzle And Spill Pipe
| YM***00 | Nozzle, Assembly | 1 |
| YM***20 | Spring | 1 |
| YM***00 | Fuel Injection Nozzle, Assembly | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Gasket Kit
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***31 | Gasket,Head (Kit) | 1 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Lubricating Oil Pump
| YM***41 | Gasket (Kit) | 1 |
| YM***20 | Bolt,Joint (Cylinder Head Side) | 1 |
| YM***00 | Gasket,Ring (Kit) | 2 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Muffler And Mounting
| YM***60 | Support,R.H | 1 |
| YM***02 | Screw | 2 |
| YM***01 | Gasket (Kit) | 2 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Oil Filter
| YM***50 | Nut | 1 |
| YM***00 | Valve,Relief | 1 |
| YM***02 | Bolt Plated | 3 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Oil Pan
| YM***70 | Oil Pan Ass'Y | 1 |
| YM***40 | Oil Pan Ass'Y | 1 |
| YM***52 | Screw | 2 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : P.P.C. Pump And Mointing
| YM***02 | Screw | 3 |
| YM***64 | Bearing,Ball | 2 |
| YM***02 | Stud | 4 |
Komatsu : 3d84e-3g(S/N 05993-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) | 3 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Rear Hanger
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Rocker Arm
| YM***02 | Screw | 6 |
| YM***80 | Spring | 3 |
| YM***50 | Rocker Arm Ass'Y | 6 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Starting Motor (Inner Parts)
| YM***30 | Dust Cover Set | 1 |
| YM***71 | Brush Holder Ass'Y | 1 |
| YM***10 | Terminal Cover | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Starting Motor And Mounting
| YM***52 | Bolt Plated | 2 |
| (Y***2) | Starting Motor Ass'Y,(See Fig.A6210-B0a1) | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Tool
| YM***70 | Wrench | 1 |
| YM***20 | Wrench | 1 |
| YM***50 | Screw Driver | 1 |
Komatsu : 3d84e-3g(S/N 05993-Up) : Engine : Water Pump And Cooling Fan
| YM***40 | Joint | 1 |
| YM***41 | Fan,Cooling? (Stamp Mark Jt) | 1 |
| YM***02 | Bolt Plated | 2 |
Frequently asked questions
What type of engine is the Komatsu 3D84E-3G?
It is a vertical, water-cooled, 4-stroke, 3-cylinder diesel engine with a displacement of 1,496 cc and a bore of 84 mm.
What is the operating weight of machines using this engine?
Operating weight varies by configuration and series, typically ranging from 9,182 to 87,083 lb across the broader equipment class.
What replaced the Komatsu 3D84E-3G?
Specific successor model information is not documented for this exact serial range; verify with your dealer for the latest engine generation in your equipment line.
What 3D84E-3G(S/N 05993-UP) owners discuss
What are the known powertrain and hydraulic behaviors for the Komatsu 3D84E-3G engine series?
What undercarriage or wear patterns are typical for machines using the 3D84E-3G engine?
What are the common engine quirks and maintenance requirements for the 3D84E-3G series?
What are the common electrical and sensor issues reported for this engine series?
What should be checked when buying a used machine with the 3D84E-3G(S/N 05993-UP) engine?
How does the 3D84E-3G engine's hydraulic system behavior change with temperature, and what does it indicate?
What are the critical safety and maintenance checks for the 3D84E-3G engine cooling system?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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