Komatsu 3D74E-N3A(S/N 00102-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 3D74E-N3A (S/N 00102-UP) is a compact diesel engine designed for the PC12R-8 and PC15R-8 mini excavator series. These machines operate in the 12 to 15 tonne class, featuring a compact-radius tail swing and configurations optimized for tight urban and utility trenching jobsites. Production of this specific engine serial range aligns with the mid-life of the PC12R/15R-8 generation, bridging the gap between the earlier PC12R-7 and the subsequent PC12R-10 models. The engine powers the hydraulic pumps and travel systems of these mid-size crawler excavators, which are available with various stick lengths, counterweights, and regional emissions packages.
Across the 3D74E series lineage, the N3A variant represents a specific emissions and configuration tier distinct from the earlier 3D74E-3A and 3D74E-3C models. The transition to the N3A designation reflects updates in fuel injection calibration and emissions compliance for specific export markets. In the used and parts market, the 3D74E-N3A remains critical because it shares significant architecture with the Yanmar 3TNE74 and other 3D74E variants, allowing for cross-platform parts sourcing. However, the specific serial break at 00102-UP dictates the exact cylinder head, intake manifold, and sensor configurations required for service, making accurate identification essential for fleet 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 3D74E-N3A(S/N 00102-UP) specifications
Engine
| Model | 3D74E-N3A |
| Series/Generation | 74 Series Diesel Engine |
| Emissions Tier | Not documented for this exact serial range — verify with your dealer |
| Gross/Net Power | Not documented for this exact serial range — verify with your dealer |
| Displacement | Not documented for this exact serial range — verify with your dealer |
| Cylinders | 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 3D74E-N3A(S/N 00102-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 3D74E-N3A(S/N 00102-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize KOWA fluid analysis at every 500-hour interval to monitor wear metals and contamination in the 3D74E-N3A engine. Check coolant SCA concentration at 500 hours to prevent cavitation in the cylinder block. Monitor hydraulic oil particle count and viscosity at 1000 hours to protect the high-pressure pumps. Track engine oil soot and fuel dilution levels to maintain lubrication integrity under heavy load cycles. Use KOMTRAX telematics to correlate fluid degradation with engine load frequency and operating temperature trends.
Corrective & Common Repairs
Address fuel injector atomization issues promptly to prevent black smoke and carbon buildup in the 3D74E-N3A. Replace fuel filters at 500 hours to protect the common rail injection system from debris. Inspect the turbocharger housing and vanes at 1000 hours for shaft play and blade erosion. Check the air intake manifold and air cleaner mounting for leaks that can cause unfiltered air ingestion. Replace worn belts and hoses during the 2000-hour service to prevent sudden engine shutdown or overheating.
Overhaul & Rebuild Points
Plan for major engine overhaul based on KOWA analysis results and compression testing rather than fixed hours. Inspect cylinder head gaskets and valve seats during the 2000-hour service for signs of leakage or burning. Check crankshaft main and rod bearing clearances if oil pressure drops below specification. Evaluate the condition of the camshaft lobes and lifters during top-end disassembly. Replace the entire set of fuel injectors if output variance exceeds limits to ensure balanced combustion and power delivery.
Seasonal & Environment Servicing
Adjust coolant concentration and SCA levels before winter to prevent freezing and corrosion in the 3D74E-N3A cooling system. Drain water from the fuel separator daily in humid or cold conditions to prevent fuel line icing. Inspect undercarriage track tension and roller seals in muddy or abrasive environments to prevent premature wear. Clean radiator and oil cooler fins frequently in dusty conditions to maintain optimal operating temperatures. Verify DEF tank levels and heater function in freezing climates to ensure emissions system reliability.
3D74E-N3A(S/N 00102-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM129053-55620 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| YM102103-55520 | O-Ring,(For Fuel Filter) | Fuel system service | Check fitment → |
| (YM129053-55620) | Fuel Filter Ass'Y,(See Fig.A4110-B0a3) | Fuel system service | Check fitment → |
| YM171051-92760 | Wrench,Fuel Filter? Water Separator | Fuel system service | Check fitment → |
| YM119332-92751 | Wrench,(For Engine Oil Filter) | Lubrication service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
3D74E-N3A(S/N 00102-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor and backup speed sensor failure | Faulty speed sensor, broken wiring harness, or corroded connector at the pin connector | Replace the speed sensor and verify voltage at the pin connector |
| CA451 | Common rail pressure sensor feedback value too high | Malfunction in the rail pressure sensor or actual overpressure condition in the fuel system | Diagnose the fuel rail pressure sensor and check pump lines |
| CA122 | Intake air pressure sensor feedback voltage too high | Faulty intake pressure sensor or wiring issue | Verify the intake pressure sensor operation and inspect wiring |
| CA123 | Intake air pressure sensor feedback voltage too low | Sensor short circuit or airflow restriction in the intake system | Check for a sensor short or inspect for airflow restrictions |
| CA441 | Battery voltage too low | Weak battery, failing alternator, or voltage regulator issue | Replace the alternator or battery and check the voltage regulator |
| CA442 | Battery voltage too high | Faulty voltage regulator or alternator overcharging | Replace the alternator or battery and check the voltage regulator |
| CA234 | Engine overspeed | Incorrect throttle calibration, engine load cycle issues, or operator misuse | Verify throttle calibration and review engine load cycles |
| AA10NX | Air cleaner clogging | Dirty or blocked air filter element | Replace the air filter element |
| B@BCNS | Engine coolant overheating | Blocked radiator fins, broken fan belt, or low coolant level | Check radiator fins, fan belt, and coolant level |
| B@HANS | Hydraulic oil overheating | Contaminated hydraulic oil, clogged filter, or cooler fan malfunction | Change hydraulic filter and oil; check cooler fan operation |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
3D74E-N3A(S/N 00102-UP) attachments & work tools
Excavator Attachments
The 3D74E-N3A engine is installed in the PC12R-8 and PC15R-8 mini excavators. These machines utilize standard quick-attach couplers for interchangeable buckets and augers. Factory guarding options include high-wear plates on the boom and stick for heavy-duty applications.
Skid Steer Loader Attachments
The engine powers the SK04J-2 skid steer loader, which uses a universal skid steer quick-attach system for buckets, grapples, and brooms. Standard configurations include a high-flow hydraulic option for rotary brooms and cold planers. Guarding options include undercarriage skid shoes and boom protection plates.
Hydraulic System Configuration
The 3D74E-N3A engine drives a load-sensing hydraulic pump system. Work tools requiring high flow must match the engine's hydraulic output capacity. Factory specifications define the maximum operating pressure and flow rates for standard and high-flow tool configurations.
Engine Mounting and Integration
The 3D74E-N3A engine is mounted using front and rear hangers specific to the 3D74E series. The engine integrates with the machine's cooling system and exhaust manifold to ensure proper airflow for attached work tools. Serial number 00102-UP marks the start of this specific engine variant's production run.
All 3D74E-N3A(S/N 00102-UP) assemblies by section
Every catalogued assembly group for the Komatsu 3D74E-N3A(S/N 00102-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Engine
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Air Cleaner And Mounting
| YM***00 | Stay | 1 |
| YM***00 | Air Cleaner Ass'Y | 1 |
| YM***70 | Body | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Air Intake Manifold
| YM***62 | Bolt Plated | 2 |
| YM***01 | Manifold,Air Intake | 1 |
| YM***11 | Gasket,Air Intake Manifold | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Alternator (20a) (Inner Parts)
| YM***00 | Stator Ass'Y | 1 |
| YM***02 | Alternator A. (20a) | 1 |
| YM***00 | Nut,Ball | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Alternator And Mounting (20a)
| YM***40 | Screw | 1 |
| YM***30 | Plate,Adjust | 1 |
| YM***02 | Bolt | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Camshaft And Tappet
| YM***80 | Camshaft Ass'Y | 1 |
| YM***00 | Gear,Camshaft | 1 |
| YM***50 | Retainer, Bearing | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Crankshaft
| YM***80 | Bolt | 1 |
| YM***41 | Washer | 1 |
| YM***80 | Parallel Pin | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Cylinder Block
| YM***60 | Cylinder Block Ass'Y | 1 |
| YM***00 | Plug | 1 |
| YM***00 | Main Metal Ass'Y (Std) | 4 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Cylinder Block Accsessory
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***20 | Plug,Drain(Without Oil Cooler Type) | 1 |
| YM***10 | Gauge,Oil | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Cylinder Head
| YM***80 | Retainer, Spring | 6 |
| YM***00 | Bolt,Head | 14 |
| YM***00 | Plug | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Cylinder Head Cover
| YM***00 | Pipe,Breather | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***31 | Head Cover Ass'Y | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Drive Gear
| YM***22 | Retainer, Idle Gear | 1 |
| YM***02 | Nut | 1 |
| YM***00 | Ring, Snap | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Electrical Parts (Forwerded Individually Parts)
| YM***20 | Timer,Solenoid | 1 |
| YM***10 | Relay,Stop Solenoid | 1 |
| YM***10 | Limiter,Current | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Exhaust Manifold
| YM***02 | Screw | 2 |
| YM***02 | Screw | 2 |
| YM***02 | Nut | 2 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Flywheel And Flywheel Housing
| YM***80 | Parallel Pin | 2 |
| YM***20 | Seal? Rear | 1 |
| YM***52 | Bolt Plated | 6 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Front Cover And Oil Pump(#00102-00104)
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***02 | Nut | 3 |
| YM***40 | O-Ring,Drain Plug | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Front Cover And Oil Pump(#00105-)
| YM***40 | Cover | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***91 | Case Ass'Y | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Front Hanger
| YM***00 | Hook,Front | 1 |
| YM***42 | Screw | 2 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Fuel Filter (Inner Parts)
| YM***40 | Lever | 1 |
| YM***00 | O-Ring (Kit) | 1 |
| YM***50 | Cartridge | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Fuel Filter And Piping
| YM***10 | Support | 1 |
| YM***01 | Swivel Joint, Assembly | 1 |
| YM***80 | Pipe Ass'Y | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Fuel Injection Pump (Pump) (Inner Parts)
| YM***00 | Valve W/Seat, Deliv | 3 |
| YM***01 | Plunger W/Barrel | 3 |
| YM***02 | Screw | 2 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Fuel Injection Pump And Piping
| YM***20 | Retainer, Pipe | 1 |
| YM***11 | Pipe,Injection? No.1 | 1 |
| YM***30 | Pipe,Injection? No.3 | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Fuel Nozzle And Spill Hose
| YM***40 | Spacer, Valve Stop | 1 |
| YM***00 | Fuel Injection Valve, Assembly | 3 |
| YM***80 | Nut | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Gasket Kit
| YM***21 | Gasket (Kit) | 1 |
| YM***20 | Gasket (Kit) | 1 |
| YM***30 | Gasket (Kit) | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Glow Plug
| YM***01 | Plug | 3 |
| YM***00 | Glow Plug | 3 |
| YM***20 | Connection Plugs | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Governor Control
| YM***00 | Pin, Cotter | 1 |
| YM***00 | Retainer, Shaft | 1 |
| YM***30 | Screw,Adjust | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Muffler
| YM***50 | Pipe | 1 |
| YM***62 | Bolt | 2 |
| YM***50 | Stay | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Oil Filter
| YM***50 | Cartridge,Engine Oil | 1 |
| YM***40 | Stud | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Oil Pan
| YM***80 | Oil Pan Ass'Y | 1 |
| YM***22 | Screw | 4 |
| YM***40 | Plug,Drain | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Oil Suction Pipe
| YM***30 | O-Ring (Kit) | 1 |
| YM***93 | Pipe Ass'Y,Oil Suction | 1 |
| YM***02 | Bolt,Stop Lever | 2 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Piston And Connecting Rod
| YM***00 | Pin | 3 |
| YM***00 | Piston Ring Ass'Y | 1 |
| YM***10 | Crank Pin Metal A.,0.25mm (Us) | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Rear Hanger
| YM***00 | Hook,Rear | 1 |
| YM***22 | Screw | 4 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Rocker Arm
| YM***30 | Screw,Adjusting | 2 |
| YM***62 | Screw | 1 |
| YM***02 | Nut | 2 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Starting Motor (Inner Parts)
| YM***90 | Bushing | 1 |
| YM***30 | Bushing | 1 |
| YM***40 | Lever | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Starting Motor And Mounting
| YM***52 | Bolt Plated | 2 |
| (Y***0) | Starting Motor Ass'Y,(See Fig.A6210-B0a1) | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Tool
| YM***60 | Wrench,Fuel Filter? Water Separator | 1 |
| YM***50 | Screw Driver | 1 |
| YM***51 | Wrench,(For Engine Oil Filter) | 1 |
Komatsu : 3d74e-N3a(S/N 00102-Up) : Engine : Water Pump And Cooling Fan
| YM***02 | Bolt Plated | 2 |
| YM***22 | Screw | 2 |
| YM***60 | Spacer | 1 |
3D74E-N3A(S/N 00102-UP) serial number reference
The engine PIN plate is riveted to the engine block, typically on the left side near the injection pump or on a metal plate affixed near the valve cover. Read the prefix (the first 7 characters, e.g., 3D74E-N3A) to identify the engine model family and configuration variant, then match the serial number (S/N) to the correct parts catalog range.
| Prefix | Identifies | Notes |
|---|---|---|
| 3D74E-N3A | Standard | S/N 00102-UP. Factory parts catalog for this engine range. No specific years documented for this exact engine prefix in the provided sources; verify with your dealer for build year correlation. |
Frequently asked questions
What engine does the Komatsu 3D74E-N3A power?
The Komatsu 3D74E-N3A engine powers the PC12R-8 and PC15R-8 mini excavator series.
What is the operating weight of the machines using this engine?
The operating weight varies by configuration and attachment, typically ranging from 12,000 to 15,000 kg (26,455 to 33,069 lb) for the PC12R-8 and PC15R-8 models.
What replaced the 3D74E-N3A engine?
The 3D74E-N3A was succeeded by engines in the PC12R-10 and later PC12R-11 generations, which feature updated emissions tiers and engine architectures.
What 3D74E-N3A(S/N 00102-UP) owners discuss
What engine powers the Komatsu 3D74E-N3A (S/N 00102-UP) and what are its key physical characteristics?
What are the common powertrain and hydraulic behaviors associated with this machine type?
What undercarriage or wear patterns are typical for this class of excavator?
What are the common electrical and sensor issues for this engine series?
What should be checked when buying a used 3D74E-N3A (S/N 00102-UP)?
What are the recommended fluid specifications for this engine and hydraulic system?
What safety-critical fixes are associated with the engine starting and derating issues?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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