Komatsu 3D84E-5X-AB(S/N 00101-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 3D84E-5X-AB (S/N 00101-UP) is a compact, three-cylinder diesel engine manufactured by Komatsu starting in 2017. It features a 1.4-liter displacement with an 84mm bore and is designed for integration into small construction machinery such as mini excavators and skid steer loaders. The engine produces approximately 38 hp at 2700 rpm and is utilized in applications requiring reliable power in a compact footprint. It serves as a power source for equipment in the compact equipment class, supporting operations in construction, agriculture, and material handling.
The 3D84E-5X-AB represents a specific generation within the broader 3D84E series, distinguished by its serial number range and configuration. It is part of a lineage that includes non-turbo variants like the 3D84E-1FB and 3D84E-2FB, as well as other 3D84E sub-models. In the used and parts market, this engine is significant due to its widespread use in compact machinery where durability and fuel efficiency are critical. Its compatibility with specific overhaul kits and its role in powering essential compact equipment make it a key component for fleet maintenance and replacement strategies.
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-5X-AB(S/N 00101-UP) specifications
Engine
| Model | 3D84E-5X-AB |
| Type | Vertical, water-cooled, 4-stroke, 3-cylinder diesel engine |
| Displacement | 1.496 L (1,496 cm³) |
| Bore | 84 mm |
| 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 speeds | 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-5X-AB(S/N 00101-UP) maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
Servicing the 3D84E-5X-AB(S/N 00101-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize KOWA fluid analysis at every major service interval to monitor engine wear metals, hydraulic particle counts, and coolant SCA concentration. Track fuel dilution, soot levels, and viscosity changes in the engine oil to anticipate internal wear. Monitor KOMTRAX telematics for load frequency and fault codes to adjust service timing based on actual operating conditions rather than fixed hours alone. Early detection of coolant contamination or hydraulic oxidation prevents catastrophic component failure.
Corrective & Common Repairs
Address intermittent starting and dashboard failures by inspecting the 12V electrical system, including the alternator and starter motor connections. Replace fuel injectors if power loss or increased fuel consumption indicates injector wear. Clear debris from the radiator and oil cooler fins to prevent overheating. Inspect the air filter restriction indicator regularly; replace the outer element when clogged to maintain airflow. Check hydraulic hoses for cracks and leaks, replacing them before failure to avoid system pressure loss.
Overhaul & Rebuild Points
Perform major engine overhaul using kits designed for the 3D84E series when compression drops or excessive oil consumption occurs. Replace pistons, rings, and cylinder liners as a set to restore compression. Inspect the turbocharger at 1000-hour intervals for wear; replace if shaft play exceeds limits. Check valve adjustments during major services. Ensure the engine data code matches the overhaul kit specifications, as the 3D84E-5X-AB shares components with other 3D84E variants but requires precise fitment for optimal performance.
Seasonal & Environment Servicing
In cold climates, check DEF levels and ensure the cooling system uses Super-coolant AF-NAC to prevent freezing. Drain water from the fuel separator daily in humid or wet environments to prevent microbial growth. In dusty conditions, check the air filter more frequently and clean the outer element as needed. Inspect the undercarriage and track tension after operation in abrasive materials. Verify battery terminal integrity and load test the battery seasonally to ensure reliable starting in extreme temperatures.
3D84E-5X-AB(S/N 00101-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM121120-12900 | Element | Scheduled service item | Check fitment → |
| YM129004-55610 | Filter Head | Scheduled service item | Check fitment → |
| YM119802-55800 | Filter Element | Scheduled service item | Check fitment → |
| YM129150-35152 | Filter Element | Scheduled service item | Check fitment → |
| YM119802-55710 | 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-5X-AB(S/N 00101-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 issue | Replace the alternator or battery; check the voltage regulator |
| CA442 | Battery voltage too high | Faulty voltage regulator or alternator | Replace the alternator or battery; check the voltage regulator |
| CA122 | Intake air pressure high voltage | Sensor malfunction or actual overpressure | 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 |
| CA153 | Intake air temperature sensor error (high) | Sensor failure | Replace or test the IAT sensor |
| CA154 | Intake air temperature sensor error (low) | Sensor failure | Replace or test the IAT sensor |
| CA428 | Fuel moisture sensor invalid voltage (high) | Contaminated fuel or sensor harness issue | Ensure a clean fuel supply and check the moisture sensor harness |
| CA429 | Fuel moisture sensor invalid voltage (low) | Contaminated fuel or sensor harness issue | Ensure a clean fuel supply and check the moisture sensor harness |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
3D84E-5X-AB(S/N 00101-UP) attachments & work tools
Excavator Buckets
The Komatsu 3D84E-5X-AB engine powers the PC30MR-2, PC30MR-3, and PC30MR-5 mini excavators. Standard work tools include 300mm, 450mm, and 600mm digging buckets. Factory configurations typically include quick coupler systems for rapid bucket changes. Hydraulic flow requirements vary by bucket width and machine configuration.
Skid Steer Attachments
The engine is used in the SK510-5 skid steer loader. Compatible work tools include standard 1.2m³ buckets, grapples, and augers. Mounting systems utilize the universal skid steer quick-attach interface. Hydraulic kit arrangements depend on the specific attachment's flow and pressure requirements.
Roller Buckets and Drums
The JV25CW-3 and JV25DW-3 rollers utilize specific drum configurations for compaction. Factory guarding options include side cutters and wear plates tailored to the drum width. Hydraulic arrangements are integrated into the roller's vibration system rather than external work tools.
Loader Buckets
The WA30-5 and WA40-3 wheel loaders use buckets ranging from 0.5m³ to 1.2m³. Mounting systems are designed for high-torque loader arms. Hydraulic kits are standard for quick-attach mechanisms on compatible loader configurations.
All 3D84E-5X-AB(S/N 00101-UP) assemblies by section
Every catalogued assembly group for the Komatsu 3D84E-5X-AB(S/N 00101-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Engine
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Air Cleaner (Single Element)(#01020-)
| YM***60 | Bolt,Wing | 1 |
| YM***60 | Silencer | 1 |
| YM***00 | Body | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Air Intake Manifold And Connection(#01020-)
| YM***01 | Heater,Intake Air | 1 |
| YM***02 | Bolt Plated | 4 |
| YM***00 | Manifold,Air Intake | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Alternator (40a) (Inner Parts)(#01020-)
| YM***00 | Bearing,Ball | 1 |
| YM***80 | Spring | 2 |
| YM***50 | Nut | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Alternator And Mounting (40a)(#01020-)
| YM***40 | Screw | 1 |
| YM***20 | Plate,Adjust | 1 |
| YM***52 | Screw | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-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-5x-Ab(S/N 00101-Up) : Engine : Crankshaft
| YM***80 | Parallel Pin | 1 |
| YM***50 | Pulley,Crank | 1 |
| YM***01 | Gear,Crank | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Cylinder Block
| YM***30 | Main Metal Ass'Y (Std) | 4 |
| YM***50 | Plug | 1 |
| YM***20 | Screw | 8 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Cylinder Block Accsessory(#01020-)
| YM***00 | O-Ring (Kit) | 1 |
| YM***50 | Guide,Oil Gauge | 1 |
| YM***50 | Oil Pressure Transmitter | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Cylinder Head
| YM***31 | Gasket,Head (Kit) | 1 |
| YM***80 | Retainer, Spring | 6 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Cylinder Head Cover(#01020-)
| YM***10 | Retainer | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***20 | Cover | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Drive Gear(#01020-)
| YM***02 | Screw | 3 |
| YM***00 | Washer,Spring | 1 |
| YM***01 | Gear,Injection | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Electrical Parts (Forwerded Individually Parts)(#01020-)
| YM***10 | Relay,Stop Solenoid | 1 |
| YM***00 | Relay,Safety | 1 |
| YM***20 | Time Switch | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Flywheel And Flywheel Housing(#01020-)
| YM***00 | Gear,Ring | 1 |
| YM***70 | Screw | 6 |
| YM***80 | Parallel Pin | 4 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Front Cover(#01020-)
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***40 | O-Ring (Kit) | 4 |
| YM***40 | O-Ring,Drain Plug | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Front Hanger(#01020-)
| YM***00 | Suspension Plate | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Fuel Filter And Piping(#01020-)
| YM***10 | Protector | 1 |
| YM***00 | Fuel Feed Pump, Assembly | 1 |
| YM***02 | Screw | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Fuel Injection Pump And Piping(#01020-)
| YM***20 | Retainer, Pipe | 1 |
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***02 | Bolt Plated | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Fuel Nozzle And Spill Hose(#01020-)
| YM***01 | Nozzle Ass'Y | 1 |
| YM***20 | Spring | 1 |
| YM***80 | Clamp | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Gasket Kit(#01020-)
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***31 | Gasket,Head (Kit) | 1 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 3 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Lubricating Oil Pump(#01020-)
| YM***50 | Pipe | 1 |
| YM***30 | Bolt Ass'Y,Joint | 1 |
| YM***02 | Seal,Ring (Kit) | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Oil Filter(#01020-)
| YM***02 | Bolt Plated | 3 |
| YM***11 | Gasket (Kit) | 1 |
| YM***10 | Bracket | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Oil Pan(#01020-)
| YM***70 | Oil Pan Ass'Y | 1 |
| YM***40 | Plug | 1 |
| YM***52 | Screw | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Piston And Connecting Rod
| YM***00 | Screw | 2 |
| YM***00 | Crank Pin Metal A. (Std) | 1 |
| YM***80 | Piston Ass'Y | 3 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Rear Hanger(#01020-)
| YM***00 | Suspension Plate | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Rocker Arm
| YM***41 | Rocker Arm Shaft A | 1 |
| YM***50 | Rocker Arm Ass'Y | 6 |
| YM***70 | Support | 2 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Starting Motor (Inner Parts)(#01020-)
| YM***50 | Pinion Ass'Y,Pinion | 1 |
| YM***20 | Housing,Center | 1 |
| YM***90 | Spring,Brush | 4 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Starting Motor And Mounting(#01020-)
| YM***52 | Bolt Plated | 2 |
| YM***20 | Cover | 1 |
| YM***60 | Cable,Engine Side | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Tool(#01020-)
| YM***20 | Flex Horn (Option.) | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Water Pump And Cooling Fan(#01020-)
| YM***40 | Plug | 2 |
| YM***22 | Screw | 2 |
| YM***01 | Thermostat | 1 |
Komatsu : 3d84e-5x-Ab(S/N 00101-Up) : Engine : Water Separator
| YM***00 | Water Separator A | 1 |
| YM***60 | O-Ring (Kit) | 1 |
| YM***50 | O-Ring (Kit) | 1 |
3D84E-5X-AB(S/N 00101-UP) serial number reference
The engine serial 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 engine model code (e.g., 3D84E-5X-AB) followed by the serial number; the serial number identifies the specific unit within that engine generation, not a machine chassis prefix.
| Prefix | Identifies | Notes |
|---|---|---|
| 3D84E-5X-AB | Engine Model | 3-cylinder diesel engine. Serial range 00101-UP. Factory parts catalog for this engine designation confirms the start of the serial range at 00101. No specific prefix breakdown beyond the engine model code is documented for this exact serial range in the provided sources; verify with your dealer for sub-variant prefixes if applicable. |
Frequently asked questions
What engine is the Komatsu 3D84E-5X-AB?
It is a 1.4-liter, three-cylinder, water-cooled diesel engine producing 38 hp at 2700 rpm, manufactured by Komatsu since 2017.
What is the operating weight of the machine using this engine?
Operating weight varies by configuration and series; consult the specific machine's serial range specification sheet for exact values.
What replaced the Komatsu 3D84E-5X-AB?
Specific successor models are not documented for this exact serial range; verify with your dealer or official Komatsu literature for current engine replacements.
What 3D84E-5X-AB(S/N 00101-UP) owners discuss
What are the core mechanical specifications of the Komatsu 3D84E-5X-AB engine?
What hydraulic oil specifications are recommended for Komatsu excavators using this engine platform?
What are the common powertrain and hydraulic behaviors reported for Komatsu excavators in this class?
What undercarriage and wear patterns are typical for this machine type?
What are the common electrical and sensor issues associated with Komatsu excavators?
What engine performance issues are commonly reported for the 3D84E series?
What should be checked when buying a used machine with the 3D84E-5X-AB engine?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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