Komatsu 3D84-2E(S/N 00292-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 3D84-2E engine is a vertical, water-cooled, 4-stroke, 3-cylinder diesel powerplant with a displacement of 1.4 liters (1,496 cc) and a bore of 84 mm. It produces 38 hp at 2,700 rpm. This engine is primarily fitted to Komatsu mini excavators, such as the PC20 and PC30 series, and compact skid steer loaders like the SK510-5. Production of the 3D84 engine family began in 2017. It serves as a compact power source for utility and light construction applications, succeeding earlier 3D84 variants and preceding newer Tier 4 Final/Stage V compliant engines in the mini-excavator lineup.
Across the 3D84 series generations, the engine has maintained its core 3-cylinder architecture but has seen updates to fuel delivery systems and emissions control to meet evolving regulatory standards. The 3D84-2E variant is distinct in its specific serial range (S/N 00292-UP) and application in later-model mini excavators. In the used and parts market, the 3D84-2E remains relevant due to its widespread use in high-volume mini-excavator fleets. Its compact size and shared components with Yanmar 3TNE84 engines create a robust aftermarket support network, ensuring continued demand for rebuild kits, cylinder heads, and fuel system components for this specific engine code.
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 3D84-2E(S/N 00292-UP) specifications
Engine
| Model | 3D84-2E |
| Configuration | Vertical, water-cooled, 4-stroke, 3-cylinder inline diesel |
| Displacement | 1.496 L (91.3 cu in) |
| Bore x Stroke | 84 x 90 mm (3.31 x 3.54 in) |
| Net 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 3D84-2E(S/N 00292-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 3D84-2E(S/N 00292-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Komatsu Oil/Water Analysis (KOWA) at every 500-hour interval to monitor wear metals (iron, copper, lead, aluminum) and contaminants (silicon, sodium) in the engine oil. Check coolant pH, SCA concentration, and glycol content at 500 hours to prevent corrosion in the 3D84-2E's water-cooled block. Monitor hydraulic fluid particle count and viscosity at 1,000 hours to detect pump wear early. Track fuel dilution and soot levels in the oil to assess combustion efficiency in this 38 hp, 1.4-liter engine.
Corrective & Common Repairs
Address low fuel pressure issues common in the 3D84-2E by inspecting the fuel pump and injector nozzles for wear or clogging. Replace the water pump (compatible with PC20/PC30 excavators) if coolant leaks or overheating occurs. Check the crankshaft and camshaft timing marks during any valve adjustment to ensure proper synchronization. Inspect the turbocharger (if equipped) and intake manifold for carbon buildup, which can restrict airflow in this compact 3-cylinder design.
Overhaul & Rebuild Points
Plan for a major overhaul when compression drops or oil consumption exceeds limits. Use a complete overhaul kit including 3 cylinder liners, 3 pistons, STD rod bearings, and thrust washers. Replace the cylinder head gasket and valve guides/seats during any head work. Ensure the crankshaft is inspected for wear before reassembly. The 3D84-2E shares components with the Yanmar 3TNE84, allowing for compatible rebuild kits for pistons, rings, and bearings.
Seasonal & Environment Servicing
In cold climates, check the coolant concentration to prevent freezing in the 3D84-2E's cooling system. Use the correct viscosity engine oil (e.g., SAE 5W-30 or 10W-30 depending on ambient temperature) to ensure proper lubrication at startup. In dusty environments, clean the air filter outer element more frequently and check the restriction indicator daily. Inspect the radiator and oil cooler fins for debris buildup to maintain optimal heat rejection in high-temperature operations.
3D84-2E(S/N 00292-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM129100-55650 | Element,Fuel Filter | Fuel system service | Check fitment → |
| YM129100-55621 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| YM102103-55520 | O-Ring,(For Fuel Filter) | Fuel system service | Check fitment → |
| YM129436-12900 | Element,Outer | Scheduled service item | Check fitment → |
| YM129436-12910 | 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.
3D84-2E(S/N 00292-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor failure | Faulty speed sensor, broken wiring harness, or corroded connector at the pin interface | Inspect the sensor wiring and connector for damage or corrosion; replace the speed sensor if voltage readings are abnormal |
| CA111 | Internal engine controller fault | Electronic Control Module (ECM) internal hardware failure | Replace or reprogram the ECM |
| CA451 | Common rail pressure sensor feedback value too high | Malfunctioning rail pressure sensor or actual overpressure condition in the fuel system | Diagnose the fuel rail pressure sensor circuit and check for physical blockages or pump issues |
| CA122 | Intake air pressure sensor feedback voltage too high | Faulty intake pressure sensor or wiring short | Verify the intake pressure sensor operation and inspect the wiring harness for shorts |
| CA123 | Intake air pressure sensor feedback voltage too low | Sensor short circuit or severe airflow restriction upstream of the sensor | Check for sensor shorting and inspect for air filter clogging or intake blockages |
| CA441 | Battery voltage too low | Weak battery, failing alternator, or loose connections | Check the battery charge state, inspect the alternator output, and tighten all ground connections |
| CA442 | Battery voltage too high | Alternator voltage regulator failure or faulty voltage regulator | Replace the alternator or battery; check the voltage regulator output |
| CA234 | Engine overspeed | Throttle calibration error, engine load cycle anomaly, or operator misuse | Verify throttle calibration and inspect the engine load cycle parameters |
| AA10NX | Air cleaner clogging | Clogged air filter element | Replace the air filter element |
| B@BCNS | Engine coolant overheating | Low coolant level, blocked radiator fins, or failed fan belt | Check radiator fins for debris, inspect the fan belt tension, and verify coolant level |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
3D84-2E(S/N 00292-UP) attachments & work tools
Excavator Attachments
The 3D84-2E engine is identified in service documentation as powering the Komatsu PC30-7 mini excavator. Factory specifications for this class typically include standard digging buckets ranging from 0.03 to 0.05 cubic meters (0.04 to 0.07 cubic yards), with optional rock buckets available for abrasive conditions. Hydraulic breaker kits are supported via auxiliary piping options, requiring high-flow hydraulic circuits to operate impact tools effectively.
Loader Attachments
The 3D84-2E engine configuration is documented in parts databases for Komatsu WA65-3 and WA75-3 wheel loaders. Standard bucket capacities for this size class range from 0.5 to 1.0 cubic meters (0.65 to 1.3 cubic yards), with multi-purpose and grading buckets offered as common options. Quick coupler systems are factory-supported, allowing for rapid interchange between buckets, forks, and other implements without manual pinning.
Hydraulic & Power Systems
Komatsu specifies Komatsu EO (Engine Oil) and TO (Transmission Oil) for the 3D84-2E engine, with hydraulic systems requiring Komatsu HO or equivalent ISO VG46 hydraulic fluid. The engine's compact 1.4-liter displacement and 38 hp output at 2,700 rpm dictate a lower-flow hydraulic architecture compared to mid-size excavators. Auxiliary hydraulic lines must be installed to support attachments like breakers or augers, as standard configurations prioritize primary boom and stick functions.
Guarding & Configuration Options
Factory guarding options for the 3D84-2E include heavy-duty radiator screens and debris guards to protect the cooling system in dusty environments. The engine compartment features service access panels designed for routine fluid checks and filter replacements. Serial number breaks (S/N 00292-UP) indicate specific production revisions that may affect mounting bracket geometries or electrical connector types for auxiliary systems.
All 3D84-2E(S/N 00292-UP) assemblies by section
Every catalogued assembly group for the Komatsu 3D84-2E(S/N 00292-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Accessory
Komatsu : 3d84-2e(S/N 00292-Up) : Accessory : P.P.C. Pump And Mounting(#03321-)
| YM***20 | Pump Ass'Y,Hydraulic | 1 |
| YM***80 | Gasket (Kit) | 1 |
| YM***81 | Gasket (Kit) | 1 |
Cooling System
Komatsu : 3d84-2e(S/N 00292-Up) : Cooling System : Water Pump And Cooling Fan(#03321-)
| YM***20 | Gasket,Water Pump | 1 |
| YM***30 | Cover | 1 |
| YM***02 | Screw | 1 |
Cylinder Block
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Camshaft And Tappet(#03321-)
| YM***80 | Camshaft Ass'Y | 1 |
| YM***01 | Gear Ass'Y,Camshaft | 1 |
| YM***50 | Bearing, Thrust | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Crankshaft(#03321-)
| YM***00 | Gear,Crank | 1 |
| YM***80 | Parallel Pin | 1 |
| YM***01 | Ball,Steel | 3 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Cylinder Block(#03321-)
| YM***20 | Plug,Drain(Without Oil Cooler Type) | 1 |
| YM***20 | Screw | 8 |
| YM***00 | Plug | 2 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Flywheel And Flywheel Housing(#03321-)
| YM***02 | Screw | 6 |
| YM***02 | Screw | 4 |
| YM***80 | Parallel Pin | 4 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Front Cover And Gear(#03321-)
| YM***90 | Front Cover Ass'Y | 1 |
| YM***10 | Washer,Seal | 7 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Oil Pan(#03321-)
| YM***50 | O-Ring | 1 |
| YM***02 | Screw | 4 |
| YM***40 | O-Ring,Drain Plug | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Block : Piston And Connecting Rod(#03321-)
| YM***20 | Piston Ass'Y | 3 |
| YM***00 | Screw | 2 |
| YM***00 | Crank Pin Metal A. (Std) | 1 |
Cylinder Head
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Air Cleaner And Mounting (Double Element Type)(#03321-)
| YM***41 | Buffle | 1 |
| YM***10 | Cap | 1 |
| YM***30 | Pan,Dust | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Air Cleaner And Mounting (Single Element Type)(#03321-)
| YM***41 | Buffle | 1 |
| YM***10 | Cap | 1 |
| YM***30 | Pan,Dust | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Air Intake Manifold And Connection(#03321-)
| YM***01 | Heater,Intake Air | 1 |
| YM***00 | Manifold,Air Intake | 1 |
| YM***11 | Gasket,Intake Manifold | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Cylinder Head Cover(#03321-)
| YM***20 | Cover, Breather | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Cylinder Head(#03321-)
| YM***80 | Retainer, Spring | 6 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
| YM***10 | Valve,Exhaust | 3 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Exhaust Manifold And Muffler(#03321-)
| YM***00 | Manifold,Exhaust | 1 |
| YM***22 | Stud | 4 |
| YM***10 | Muffler | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Cylinder Head : Rocker Arm(#03321-)
| YM***02 | Screw | 6 |
| YM***80 | Spring | 3 |
| YM***50 | Rocker Arm Ass'Y | 6 |
Electrical System
Komatsu : 3d84-2e(S/N 00292-Up) : Electrical System : Alternator (40a)(#03321-)
| YM***50 | Brush Ass'Y | 1 |
| YM***00 | Retainer,Bearing | 1 |
| YM***70 | Diode Ass'Y | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Electrical System : Alternator And Mounting (40a)(#03321-)
| YM***30 | Plate,Adjust | 1 |
| YM***02 | Nut | 1 |
| YM***02 | Nut | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Electrical System : Safety Relay(#03321-)
| YM***00 | Relay, Safety | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Electrical System : Starting Motor (1.8kw)(#03321-)
| YM***40 | Bolt,Through | 2 |
| YM***50 | Pinion Ass'Y,Pinion | 1 |
| YM***00 | Cover,Rear | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Electrical System : Starting Motor And Mounting (1.8kw)(#03321-)
| YM***52 | Bolt Plated | 2 |
| YM***02 | Nut,Rock | 1 |
| YM***00 | Washer,Spring | 1 |
Fuel System
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Engine Stop Motor And Mounting(#03321-18427)
| YM***80 | Ring,Snap | 1 |
| YM***00 | Pin,Cotter | 1 |
| YM***90 | Washer | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Engine Stop Motor And Mounting(#18428-)
| YM***20 | Motor Ass'Y,Engine Stop | 1 |
| YM***80 | Ring,Snap | 1 |
| YM***00 | Pin,Cotter | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Filter And Piping(#03321-)
| YM***70 | Union | 1 |
| YM***10 | Hose,(See Fig.0415-17?0416-17) | 1 |
| YM***00 | O-Ring (Kit) | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2)(#03321-)
| YM***02 | Lever Ass'Y,Stop | 1 |
| YM***10 | Pin,Stop Lever | 1 |
| YM***00 | O-Ring (Kit) | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2)(#03321-)
| YM***01 | Weight Assembly., Governor | 1 |
| YM***90 | Shaft,Governor Lever | 1 |
| YM***50 | Angleich Ass'Y | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Injection Pump (Pump) (1/2)(#03321-)
| YM***90 | Injection Pump Ass'Y | 1 |
| YM***50 | Kit, Shim | 1 |
| YM***10 | Plate? Caution | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Injection Pump (Pump) (2/2)(#03321-)
| YM***70 | Retainer, Spring | 3 |
| YM***00 | Plunger Ass'Y | 3 |
| YM***02 | Screw | 2 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Injection Pump And Piping(#03321-)
| YM***20 | Retainer, Pipe | 1 |
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***30 | Bolt | 2 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Fuel Nozzle And Spill Pipe(#03321-)
| YM***20 | Spring | 1 |
| YM***00 | Fuel Injection Nozzle, Assembly | 1 |
| YM***80 | Seat,Nozzle (Kit) | 3 |
Komatsu : 3d84-2e(S/N 00292-Up) : Fuel System : Water Separator And Piping(#03321-)
| YM***00 | Gasket | 2 |
| YM***00 | O-Ring (Kit) | 1 |
| YM***50 | Plug,Air | 2 |
Lubricating Oil System
Komatsu : 3d84-2e(S/N 00292-Up) : Lubricating Oil System : Lubricating Oil Filter And Mounting(#03321-)
| YM***50 | Nut | 1 |
| YM***02 | Bolt Plated | 3 |
| YM***50 | Cartridge,Engine | 1 |
Komatsu : 3d84-2e(S/N 00292-Up) : Lubricating Oil System : Lubricating Oil Pump And Piping(#03321-)
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***40 | Gasket,Inlet Pipe | 1 |
| YM***41 | Gasket (Kit) | 1 |
Tool And Engine Kit
Komatsu : 3d84-2e(S/N 00292-Up) : Tool And Engine Kit : Gasket Kit(#03321-)
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***20 | Gasket,Water Pump | 1 |
| YM***10 | Gasket (Kit) | 1 |
Frequently asked questions
What engine does the Komatsu 3D84-2E use?
The Komatsu 3D84-2E is a vertical, water-cooled, 4-stroke, 3-cylinder diesel engine with a displacement of 1.4 liters (1,496 cc) and a bore of 84 mm. It produces 38 hp at 2,700 rpm. It is closely related to the Yanmar 3TNE84 engine.
What is the operating weight of the machine using the 3D84-2E engine?
Operating weight varies by configuration and series. The 3D84-2E engine is typically found in Komatsu mini excavators (e.g., PC20, PC30 series) and skid steer loaders (e.g., SK510-5). Specific weights depend on the exact machine model, attachment package, and counterweight configuration. Consult the specific machine's operation and maintenance manual for precise weight data.
What replaced the Komatsu 3D84-2E engine?
The 3D84-2E is part of the broader 3D84 engine family, which has been succeeded by newer Komatsu engines meeting Tier 4 Final/Stage V emissions standards. Specific replacement engines vary by machine model and production year. Komatsu has transitioned to more advanced powertrains in its mini-excavator and skid steer lines, often incorporating electronic control modules and advanced emissions aftertreatment systems.
What 3D84-2E(S/N 00292-UP) owners discuss
What is the engine architecture and primary application for the Komatsu 3D84-2E?
What are the known hydraulic behaviors and common failure patterns for machines powered by this engine?
What undercarriage and wear patterns are typical for this machine class?
What are the common engine quirks and maintenance requirements for the 3D84-2E series?
What electrical and sensor issues are frequently reported by owners?
What fluids and specifications should be used for the Komatsu 3D84-2E engine and hydraulic system?
What should be checked when buying a used machine with a 3D84-2E engine?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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