Komatsu 3D84E-3LN(S/N 05993-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 3D84E-3LN engine (S/N 05993-UP) is a compact, water-cooled, 4-stroke, 3-cylinder diesel powerplant manufactured by Komatsu starting in 2017. With a displacement of 1.4 liters (1,496 cc) and a bore of 84 mm, it delivers approximately 38 hp at 2,700 rpm. This engine powers the Komatsu PC30MR-2 series mini excavators, a class of compact machines designed for tight-access construction, utility, and landscaping work. The PC30MR-2 replaced earlier PC30MR iterations, offering improved hydraulic efficiency and emissions compliance. Configurations vary by region and attachment package, but the core powertrain remains a vertical, inline-3 design optimized for durability in heavy-duty cycles.
Across the 3D84E series generations, Komatsu refined emissions handling and fuel injection precision to meet evolving Tier 4/Stage V standards while maintaining the engine's compact footprint. The 3D84E-3LN variant specifically addresses the needs of the PC30MR-2 platform, balancing power density with serviceability. In the used and parts market, this engine remains critical because its shared architecture with Yanmar 3TNE84D platforms allows for cross-compatibility in overhaul kits and core components. Its widespread use in the popular PC30MR-2 mini excavator ensures a robust supply of aftermarket support, making it a cost-effective choice for fleet operators managing aging compact equipment.
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-3LN(S/N 05993-UP) specifications
Engine
| Model | 3D84E-3LN |
| Type | Vertical, water-cooled, 4-stroke, 3-cylinder diesel engine |
| Displacement | 1,496 L (1,496 liters) |
| Bore x Stroke | 84 x 90 mm |
| Gross/Net Power | 38 hp at 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 |
| 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-3LN(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-3LN(S/N 05993-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize KOWA fluid analysis at every 500-hour interval to monitor wear metals (iron, copper, lead, aluminum) and contaminants (silicon, sodium) in the 3D84E-3LN engine. Check hydraulic oil particle count and viscosity to protect the PC30MR-2's high-pressure pumps. Test coolant SCA concentration and pH to prevent liner cavitation in the 1.4L block. Monitor DEF levels for emissions compliance. Early detection of fuel dilution or coolant intrusion in the oil prevents catastrophic bearing failure in this compact, high-output engine.
Corrective & Common Repairs
Address frequent 3D84E-3LN issues by inspecting the fuel injection system for leaks or clogged injectors, common in mini excavator duty cycles. Replace worn turbocharger seals if blue smoke appears under load. Check the water pump impeller for erosion if overheating occurs. Inspect the alternator brushes and voltage regulator for charging faults. Tighten exhaust manifold bolts to prevent leaks that can damage the turbo. Replace cracked hydraulic hoses on the PC30MR-2 boom and stick to maintain hydraulic flow and prevent cylinder drift.
Overhaul & Rebuild Points
Plan the 3D84E-3LN overhaul when compression drops below spec or oil consumption exceeds limits. Replace cylinder liners, pistons, and rings using the shared 3D84E/Yanmar 3TNE84D kit. Inspect the crankshaft main and rod bearings for scoring. Recondition the cylinder head, replacing valves and guides. Replace the turbocharger if shaft play is excessive. Rebuild the fuel injection pump if delivery pressure is inconsistent. Ensure the timing gear set is replaced to maintain precise valve timing for optimal combustion efficiency.
Seasonal & Environment Servicing
In cold climates, use low-temperature hydraulic oil and ensure the PC30MR-2's cooling system is flushed with fresh super-coolant AF-NAC to prevent freezing. Check the battery heater and pre-lube system for reliable starts. In dusty environments, inspect the air cleaner element more frequently and clean the radiator fins daily to prevent overheating. In high-humidity areas, check the fuel water separator daily to prevent microbial growth. Adjust track tension on the undercarriage to compensate for mud buildup and reduce wear on rollers and sprockets.
3D84E-3LN(S/N 05993-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| (YM129612-55620) | Fuel Filter Ass'Y,(See Fig.A4110-B0a2a) | Fuel system service | Check fitment → |
| YM129100-55650 | Element,Fuel Filter | Fuel system service | Check fitment → |
| YM129612-55620 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| YM119808-12520 | Element,Outer | Scheduled service item | Check fitment → |
| YM129150-35152 | Filter 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-3LN(S/N 05993-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor and backup speed sensor failure | Broken sensor, wiring issue, or connector corrosion | Replace the speed sensor and verify voltage at the pin connector |
| CA111 | Internal engine controller fault | ECM hardware or software failure | Replace or reprogram the ECM |
| 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 |
| CA452 | Common rail pressure sensor feedback value too low | Fuel leak, sensor failure, or supply pump issue | Diagnose the fuel rail pressure sensor or pump lines |
| CA122 | Intake air pressure sensor feedback voltage too high | Sensor malfunction or wiring short | Verify the intake pressure sensor and wiring |
| CA123 | Intake air pressure sensor feedback voltage too low | Sensor short or airflow restriction | Check for a sensor short or an airflow restriction |
| CA153 | Intake air temperature sensor feedback voltage too high | Sensor failure or wiring issue | Replace or test the IAT sensor |
| CA154 | Intake air temperature sensor feedback voltage too low | Sensor failure or wiring issue | Replace or test the IAT sensor |
| CA441 | Battery voltage too low | Weak battery, alternator failure, or loose connections | 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 |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
3D84E-3LN(S/N 05993-UP) attachments & work tools
Excavator Attachments
The 3D84E-3LN engine powers compact excavator models such as the PC30-6, PC30-7, PC30MR-1, PC30MR-3, PC30MR-5, PC30MRX-1, PC30R-8, PC30UU, PC30UU-3, PC30UU-6, PC35R-7, PC35R-8, PC35MRX-1A, PC38UU-1, PC38UU-2, and PC38UU-3. Typical work tools include digging buckets, grading buckets, and trenching buckets sized for the 3-ton class. Coupler systems vary by machine configuration; standard quick couplers are common on later models like the PC30UU series. Hydraulic kit requirements depend on the specific attachment flow and pressure ratings, often requiring auxiliary hydraulic lines or a pilot-operated coupler kit.
Skid Steer Attachments
The engine is used in Komatsu skid steer loaders SK05J-2 and SK07-2. Compatible work tools include general purpose buckets, grading buckets, pallet forks, and brooms. These machines typically utilize a universal skid steer quick-attach interface. Hydraulic options may include high-flow auxiliary circuits for tools like cold planers or hydraulic breakers, depending on the specific machine configuration and factory-installed hydraulic package.
Wheel Loader Attachments
The 3D84E-3LN engine is found in Komatsu wheel loaders WA30-2, WA30-5-NA, WA30-5-W, WA30-5-X, WA40-3, WA40-3RS-X, WA40-3SF-X, WA40-3-X, WA50-3, and WA50-3-X. Standard work tools include general purpose buckets, rock buckets, and pallet forks. Mounting systems are specific to the loader model, typically using a pin-on or quick-attach mechanism. Hydraulic configurations vary by series, with some models offering optional high-flow hydraulics for specialized attachments.
Road Cutter Attachments
The Komatsu Road Cutter GC50-1 utilizes the 3D84E-3LN engine. Work tools consist of cutting drums with varying tooth configurations for asphalt and concrete removal. The attachment is integrated into the machine frame, requiring specific hydraulic connections for drum rotation and depth control. Factory guarding options include dust suppression systems and safety shields tailored to the cutting drum assembly.
Roller Attachments
The engine powers Komatsu vibratory rollers JV25CW-2, JV25DW-2, JV25W-2, JV40CW-3, and JV40DW-3. Work tools are limited to the drum assemblies themselves, with options for smooth, padfoot, or combination drums depending on the model. Hydraulic systems drive the vibration mechanism and steering. Factory configurations may include water spray systems for dust control and edge protection guards for the drum ends.
Generator Attachments
The 3D84E-3LN engine is used in Kohler generator sets including models 10ROY, 10ROZ, 10RO91, 11.5EFOZ, 12KW, 14EFOZ, 13EFOZ, 15EOZ, and 15.5EOZ. The primary 'work tool' is the alternator assembly, with output configurations varying by voltage and phase requirements. Factory options include sound attenuation enclosures, transfer switch interfaces, and remote monitoring packages. Hydraulic kits are not applicable as these are stationary power units.
Agricultural/Industrial Attachments
The engine is used in the Gravely Chipper PRO CHIP 944 and Doosan Loader 602 PLUS/DSL602. For the chipper, the work tool is the cutting drum and feed mechanism. For the Doosan loader, standard buckets and forks are used. Mounting systems are specific to each machine type. Hydraulic requirements for the chipper involve high-flow circuits for the drum and feed rollers, while the loader follows standard wheel loader hydraulic configurations.
All 3D84E-3LN(S/N 05993-UP) assemblies by section
Every catalogued assembly group for the Komatsu 3D84E-3LN(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-3ln(S/N 05993-Up) : Engine : Air Cleaner And Mounting(#20614-)
| YM***90 | Gasket,(Not Shown) | 1 |
| YM***00 | Air Cleaner Ass'Y | 1 |
| YM***20 | Element,Outer | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Air Intake Manifold And Connection(#11259-)
| YM***00 | Manifold,Air Intake | 1 |
| YM***02 | Bolt Plated | 4 |
| YM***02 | Screw | 2 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Alternator (40a) (Inner Parts)(#31420-)
| YM***20 | Rear Bracket Ass'Y | 1 |
| YM***30 | Front Bracket Ass'Y | 1 |
| YM***00 | Rotor Ass'Y | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Alternator And Mounting (40a)(#39676-)
| YM***02 | Nut | 1 |
| YM***02 | Screw | 1 |
| YM***40 | Screw | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Camshaft And Tappet(#18941-)
| YM***80 | Camshaft Ass'Y | 1 |
| YM***01 | Gear Ass'Y,Camshaft | 1 |
| YM***50 | Bearing, Thrust | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Crankshaft(#39676-)
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Cylinder Block
| YM***30 | Main Metal Ass'Y (Std) | 4 |
| YM***00 | Plug | 1 |
| YM***50 | Plug | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Cylinder Block Accessory(#11259-)
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***20 | Plug,Drain(Without Oil Cooler Type) | 1 |
| YM***10 | Guide,Level Gauge | 1 |
Komatsu : 3d84e-3ln(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-3ln(S/N 05993-Up) : Engine : Cylinder Head Cover(#18941-)
| YM***20 | Cover, Breather | 1 |
| YM***70 | Clamp | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Drive Gear(#31175-)
| YM***01 | Idler Gear Ass'Y,Idler | 1 |
| YM***52 | Screw | 2 |
| YM***20 | Bush,Idle Gear (Repair Part) | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Electrical Parts (Forwerded Individually Parts)(#18941-)
| YM***00 | Relay Ass'Y,Safety | 1 |
| YM***20 | Timer,Solenoid | 1 |
| YM***10 | Relay,Stop Solenoid | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Exhaust Manifold(#39676-)
| YM***02 | Screw | 4 |
| YM***00 | Cover | 1 |
| YM***02 | Stud | 2 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Flywheel And Flywheel Housing(#18941-)
| YM***02 | Screw | 4 |
| YM***70 | Screw | 6 |
| YM***80 | Parallel Pin | 4 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Front Cover(#39676-)
| YM***02 | Bolt Plated | 2 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Front Hanger(#18941-)
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Filter And Piping(#21072-)
| YM***70 | Union | 1 |
| YM***10 | Pipe | 1 |
| YM***02 | Bolt Plated | 2 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Filter(#21072-)
| YM***10 | Cup, Strainer | 1 |
| YM***00 | O-Ring (Kit) | 1 |
| YM***70 | Lever | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)(#39676-)
| YM***70 | Nut | 1 |
| YM***40 | Lever,Control | 1 |
| YM***30 | Spacer,Lever Shaft | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)(#39676-)
| YM***50 | Angleich Ass'Y | 1 |
| YM***00 | Washer,Spring | 1 |
| YM***40 | Link? L=30.5,L=30.5 (Mark 05) | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)(#39676-)
| YM***50 | Injection Pump Ass'Y | 1 |
| YM***50 | Kit, Shim | 1 |
| YM***10 | Flange | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)(#39676-)
| YM***70 | Retainer, Spring | 3 |
| YM***02 | Screw | 2 |
| YM***30 | Spacer,Spring | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Fuel Injection Pump And Piping(#39676-)
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***60 | Nut | 3 |
| YM***30 | Pipe,Injection | 1 |
Komatsu : 3d84e-3ln(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-3ln(S/N 05993-Up) : Engine : Gasket Kit(#21072-)
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***31 | Gasket,Head (Kit) | 1 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Lubricating Oil Pump(#11259-)
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Muffler And Mounting(#39676-)
| YM***11 | Gasket,Muffler (Kit) | 1 |
| YM***20 | Muffler | 1 |
| YM***90 | Clamp Ass'Y | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Oil Filter(#18941-)
| YM***00 | Pipe,Breather | 1 |
| YM***50 | Nut | 1 |
| YM***00 | Cover | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Oil Pan(#18941-)
| YM***52 | Screw | 2 |
| YM***52 | Screw | 20 |
| YM***40 | Plug,Drain | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Piston And Connecting Rod(#23864-)
| YM***00 | Screw | 2 |
| YM***00 | Crank Pin Metal A. (Std) | 1 |
| YM***10 | Assembly, Piston (+0.25 mm) | 3 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Rear Hanger(#18941-)
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Rocker Arm
| YM***02 | Screw | 6 |
| YM***80 | Spring | 3 |
| YM***50 | Rocker Arm Ass'Y | 6 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Starting Motor (1.2kw) (Inner Parts)(#21072-)
| YM***20 | Holder Ass'Y,Brush | 1 |
| YM***50 | Stopper Ass'Y | 1 |
| YM***20 | Pinion, Assembly | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Starting Motor And Mounting (1.2kw)(#21072-)
| YM***52 | Bolt Plated | 2 |
| YM***02 | Nut,Rock | 1 |
| YM***00 | Washer,Spring | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Tool(#21072-)
| YM***20 | Flex Horn (Option.) | 1 |
Komatsu : 3d84e-3ln(S/N 05993-Up) : Engine : Water Pump And Cooling Fan(#39676-)
| YM***40 | Joint | 1 |
| YM***22 | Screw | 2 |
| YM***52 | Bolt Plated | 4 |
Frequently asked questions
What engine does the Komatsu 3D84E-3LN use?
The Komatsu 3D84E-3LN is a 1.4-liter (1,496 cc), water-cooled, 4-stroke, 3-cylinder diesel engine producing approximately 38 hp at 2,700 rpm. It is used in the Komatsu PC30MR-2 series mini excavators.
What is the operating weight of the machine powered by this engine?
The operating weight varies by configuration and attachment package. For the Komatsu PC30MR-2 series, the weight typically ranges from 3,000 kg to 3,500 kg (6,614 lb to 7,716 lb) depending on the boom, stick, and counterweight setup.
What replaced the Komatsu 3D84E-3LN engine?
The 3D84E-3LN is part of the 3D84E series, which has been succeeded by newer emissions-compliant engine platforms such as the SAA4D94E and SAA6D107E series in modern Komatsu excavators. The specific PC30MR-2 model has been succeeded by the PC30MR-3 and newer generations with updated powertrains.
What 3D84E-3LN(S/N 05993-UP) owners discuss
What are the known powertrain and hydraulic behaviors for the Komatsu 3D84E-3LN engine series?
What undercarriage or wear patterns are typical for machines using this engine type?
What are the specific quirks of the 3D84E-3LN engine series per community reports?
What are the common electrical or sensor issues reported for this machine type?
What should be checked when buying a used machine with the 3D84E-3LN engine (S/N 05993-UP)?
What are the critical safety considerations for the hydraulic and cooling systems?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific 3D84E-3LN(S/N 05993-UP) part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.