Komatsu 3D84E-3K(S/N 05993-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 3D84E-3K engine (S/N 05993-UP) is a vertical, water-cooled, 4-stroke, 3-cylinder diesel powerplant with a displacement of 1.496 liters and a bore of 84 mm. It delivers 38 hp at 2,700 rpm and is primarily integrated into compact construction machinery such as the Komatsu PC30 MR excavator and SK510-5 skid steer loader. Manufactured since 2017, this engine belongs to the 3D84 series lineage, succeeding earlier 3D82 and 3D84 variants. It is designed for utility and light earthmoving applications where compact dimensions and moderate weight allow for easy integration into smaller chassis configurations.
Across the 3D84 series generations, the engine has maintained its core 3-cylinder architecture while adapting to evolving emissions standards and operational demands. The 3D84E-3K variant specifically serves the later production serial range starting at 05993, distinguishing it from earlier 3A, 3B, and 3C sub-models. In the used and parts market, this engine remains critical due to its widespread use in high-volume compact equipment. Its mechanical simplicity and shared overhaul kit compatibility with Yanmar 3TNE84D engines make it a cost-effective power source for fleet managers, while its specific serial designation ensures accurate parts sourcing for rebuild and maintenance.
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-3K(S/N 05993-UP) specifications
Engine
| Model | 3D84E-3K |
| Type | 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) |
| 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-3K(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-3K(S/N 05993-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize KOWA fluid analysis at every 500-hour interval to monitor engine wear metals (iron, copper, lead, aluminum) and contaminants like silicon (dirt) or sodium (coolant). Track fuel dilution, soot levels, and viscosity changes in the 3D84E-3K engine oil. For the hydraulic system, analyze particle count (ISO cleanliness), pump/valve wear metals, water content, and oxidation. Coolant analysis must verify pH, SCA concentration, glycol content, and conductivity to prevent corrosion and scaling in the 1.496-liter displacement block.
Corrective & Common Repairs
Address frequent 3D84E-3K issues by inspecting the air cleaner element for clogging and replacing the outer element at 1,000 hours. Check the fuel system for water accumulation in the separator, draining daily. Inspect the turbocharger for shaft play and housing damage at 1,000-hour intervals. Verify belt and hose integrity for cracks or leaks during every 250-hour service. Monitor the battery terminals for corrosion and perform load tests at 500 hours to ensure reliable starting in compact excavator and skid steer applications.
Overhaul & Rebuild Points
The 3D84E-3K engine utilizes a major overhaul kit compatible with the 3D84N and S3D84E series. Rebuild intervals typically align with high-hour thresholds where cylinder liner wear, piston ring fatigue, or bearing clearance exceeds limits. The engine features a 84 mm bore and 3-cylinder configuration. Overhaul procedures include disassembly of the fuel system, lubrication system, and exhaust components. Use factory-specified torque values for the cylinder head and main bearings. The overhaul kit includes cylinder liners and matching pistons to restore compression and power output.
Seasonal & Environment Servicing
In cold climates, monitor DEF levels and ensure the cooling system uses Komatsu Super Coolant AF-NAC to prevent freezing. Check the battery charge state frequently as cold temperatures reduce cranking power. In dusty environments, inspect the air filter restriction indicator more often than the standard 250-hour interval and clean the radiator and oil cooler fins daily to prevent overheating. In high-humidity or coastal areas, inspect hydraulic hoses and electrical connections for corrosion. Ensure the fuel water separator is drained daily to prevent microbial growth in the fuel system.
3D84E-3K(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 → |
| YM119640-92750 | Wrench,Oil Filter? (Pc38uu) | Lubrication service | Check fitment → |
| YM119808-12520 | Element,Outer | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
3D84E-3K(S/N 05993-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 |
| CA111 | Internal engine controller fault | ECM hardware failure | Replace or reprogram the ECM |
| 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 |
| CA122 | Intake air pressure high voltage | Sensor malfunction or actual overpressure condition | 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 |
| CA451 | Common rail pressure sensor feedback value too high | Fuel rail sensor malfunction or actual overpressure | Diagnose the fuel rail pressure sensor or pump lines |
| CA452 | Common rail pressure sensor feedback value too low | Fuel rail sensor malfunction or low pressure | 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 |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
All 3D84E-3K(S/N 05993-UP) assemblies by section
Every catalogued assembly group for the Komatsu 3D84E-3K(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-3k(S/N 05993-Up) : Engine : Air Cleaner And Mounting(#18941-20613)
| YM***90 | Gasket,(Not Shown) | 1 |
| YM***00 | Air Cleaner Ass'Y | 1 |
| YM***60 | Support | 1 |
Komatsu : 3d84e-3k(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-3k(S/N 05993-Up) : Engine : Air Intake Manifold And Connection(#18941-)
| YM***00 | Manifold,Air Intake | 1 |
| YM***02 | Bolt Plated | 4 |
| YM***02 | Screw | 2 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Alternator (40a) (Inner Parts)(#18941-)
| YM***20 | Rear Bracket Ass'Y | 1 |
| YM***30 | Front Bracket Ass'Y | 1 |
| YM***00 | Rotor Ass'Y | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Alternator And Mounting (40a)(#18941-)
| YM***02 | Nut | 1 |
| YM***02 | Nut | 1 |
| YM***20 | Adjuster, Belt | 1 |
Komatsu : 3d84e-3k(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-3k(S/N 05993-Up) : Engine : Crankshaft
| YM***00 | Gear,Crank | 1 |
| YM***80 | Parallel Pin | 1 |
| YM***10 | Spring Pin | 1 |
Komatsu : 3d84e-3k(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-3k(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-3k(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-3k(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-3k(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-3k(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-3k(S/N 05993-Up) : Engine : Exhaust Manifold(#18941-)
| YM***02 | Nut | 2 |
| YM***00 | Manifold,Exhaust | 1 |
| YM***02 | Stud | 2 |
Komatsu : 3d84e-3k(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-3k(S/N 05993-Up) : Engine : Front Cover(#18941-)
| YM***02 | Bolt Plated | 2 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***00 | Clip,Breather Hose | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Front Hanger(#18941-)
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Filter And Piping(#18941-)
| YM***70 | Union | 1 |
| YM***10 | Pipe | 1 |
| YM***02 | Bolt Plated | 2 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Filter(#18941-)
| YM***10 | Cup, Strainer | 1 |
| YM***00 | O-Ring (Kit) | 1 |
| YM***70 | Lever | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)(#11259-)
| YM***40 | Lever,Control | 1 |
| YM***30 | Spacer,Lever Shaft | 1 |
| YM***02 | Nut | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)(#11259-)
| YM***01 | Weight Assembly., Governor | 1 |
| YM***50 | Angleich Ass'Y | 1 |
| YM***00 | Washer,Spring | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)(#11259-)
| YM***50 | Kit, Shim | 1 |
| YM***10 | Plate? Caution | 1 |
| YM***50 | Cover,Side | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)(#11259-)
| YM***70 | Retainer, Spring | 3 |
| YM***02 | Screw | 2 |
| YM***30 | Spacer,Spring | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Fuel Injection Pump And Piping(#11259-)
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***02 | Nut | 3 |
| YM***11 | Pipe,Injection | 1 |
Komatsu : 3d84e-3k(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-3k(S/N 05993-Up) : Engine : Gasket Kit(#18941-)
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***31 | Gasket,Head (Kit) | 1 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Lubricating Oil Pump(#11259-)
| YM***81 | Retainer | 1 |
| YM***30 | Bolt, Assembly | 1 |
| YM***02 | Seal,Ring (Kit) | 2 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Muffler And Mounting(#18941-)
| YM***02 | Nut | 4 |
| YM***11 | Gasket,Muffler (Kit) | 1 |
| YM***90 | Clamp Ass'Y | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Oil Filter(#18941-)
| YM***00 | Pipe,Breather | 1 |
| YM***50 | Nut | 1 |
| YM***00 | Cover | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Oil Pan(#18941-)
| YM***52 | Screw | 2 |
| YM***52 | Screw | 20 |
| YM***40 | Plug,Drain | 1 |
Komatsu : 3d84e-3k(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-3k(S/N 05993-Up) : Engine : Rear Hanger(#18941-)
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Rocker Arm
| YM***02 | Screw | 6 |
| YM***80 | Spring | 3 |
| YM***50 | Rocker Arm Ass'Y | 6 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Starting Motor (1.2kw) (Inner Parts)(#18941-)
| YM***20 | Holder Ass'Y,Brush | 1 |
| YM***50 | Stopper Ass'Y | 1 |
| YM***20 | Pinion, Assembly | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Starting Motor And Mounting (1.2kw)(#18941-)
| YM***52 | Bolt Plated | 2 |
| YM***02 | Nut,Rock | 1 |
| YM***00 | Washer,Spring | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Tool(#18941-)
| YM***50 | Screw Driver | 1 |
| YM***20 | Flex Horn (Option.) | 1 |
| YM***60 | Fuel, Wrench, Strainer | 1 |
Komatsu : 3d84e-3k(S/N 05993-Up) : Engine : Water Pump And Cooling Fan(#18941-)
| YM***40 | Joint | 1 |
| YM***02 | Bolt Plated | 2 |
| YM***22 | Screw | 2 |
3D84E-3K(S/N 05993-UP) serial number reference
The 3D84E-3K PIN plate is located on the engine block, typically on the left side near the injection pump or on a metal data plate affixed near the valve cover. Read the prefix as the first alphanumeric sequence identifying the engine model (3D84E-3K), followed by the serial number starting at 05993.
| Prefix | Identifies | Notes |
|---|---|---|
| 3D84E-3K | Engine Model | Komatsu 3D84E-3K engine. Serial range 05993-UP. Verified by published references catalog listing and overhaul kit compatibility lists. Single-source confirmation for prefix-to-engine mapping; verify with dealer for specific machine build details. |
Frequently asked questions
What engine does the Komatsu 3D84E-3K (S/N 05993-UP) use?
It uses a Komatsu 3D84E-3K vertical, water-cooled, 4-stroke, 3-cylinder diesel engine with a displacement of 1.496 liters and a bore of 84 mm, producing 38 hp at 2,700 rpm.
What is the operating weight of the machine powered by this engine?
Operating weight varies by configuration/series. The 3D84E-3K engine is used in compact machinery such as the PC30 MR excavator and SK510-5 skid steer loader, which fall within the compact equipment class (typically under 20,000 lbs).
What replaced the Komatsu 3D84E-3K engine?
Specific successor engine data for the 3D84E-3K is not documented in the provided sources. The 3D84 series has evolved through multiple sub-models (3A through 3K) to meet emissions standards, but no single direct replacement model is explicitly identified for this specific serial range.
What 3D84E-3K(S/N 05993-UP) owners discuss
What are the core specifications and configuration of the Komatsu 3D84E-3K engine?
What are the common hydraulic behaviors and failure patterns associated with this engine's machine type?
What undercarriage and wear patterns are typical for machines powered by this engine?
What are the known engine quirks and maintenance requirements for the 3D84E series?
What are the common electrical and sensor issues reported for this engine type?
What fluids and specifications are recommended for the Komatsu 3D84E-3K engine and its associated systems?
What should be checked when buying a used machine with the 3D84E-3K engine?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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