Komatsuwheel loadersmall ( - wa120 / sk*)
Komatsu SK04J-2(S/N SK04JF20001-Up)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu SK04J-2 is a wheeled skid steer loader manufactured from 1999 to 2006. It features a 20.8 hp engine and has an operating weight of 1.55 tons (1,550 kg). The machine offers a bucket capacity of 0.16 m³ (0.21 cu yd) and a rated operating capacity of 390 kg (860 lb). It is part of the SK04 series lineage, succeeding the SK04-1 and preceding later compact loader generations. Configurations include standard joystick controls and various attachment options for excavation, grading, and debris removal.
Across the SK04 series, Komatsu refined the joystick control interface and hydraulic responsiveness to improve operator ease and cycle times. The SK04J-2 remains significant in the used and parts market due to its compact footprint and durable powertrain, which is widely supported by the Komatsu Genuine Lubricants and KOWA analysis ecosystem. Its continued presence in municipal and utility fleets ensures steady demand for service components and fluid specifications.
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 SK04J-2(S/N SK04JF20001-Up) specifications
Engine
| Model | 3D74E-1FC |
| Gross Power | 24.2 hp (18.0 kW) |
| Net Power | 20.8 hp (15.5 kW) |
| Displacement | 61.4 cu in (1.006 L) |
| Cylinders | 3 |
| Emissions Tier | Not documented for this exact serial range — verify with your dealer |
Weights
| Operating Weight | 3,417.2 lb (1,550 kg) |
| 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 With Bucket | 8.44 ft (2.57 m) |
| Transport Width Over Tires | 3.38 ft (1.03 m) |
| Transport Height To Top Of Cab | 6.11 ft (1.86 m) |
| Wheelbase | 2.43 ft (0.74 m) |
| Ground Clearance | 6.89 in (175 mm) |
| Clearance At Max Lift And Dump | 6.37 ft (1.94 m) |
| Reach At Max Lift And Dump | 15.36 in (390 mm) |
Performance
| Travel Speed | 5.6 mph (9 km/h) |
| Rated Operating Capacity | 859.9 lb (390 kg) |
| Breakout Force | 2,255.4 lbf (10 kN) |
| Gradeability | Not documented for this exact serial range — verify with your dealer |
Service capacities (summary)
| Fuel Tank | 7.2 gal (27.3 L) |
| Hydraulic System | 3.2 gal (12.1 L) |
| Engine Oil | 0.9 gal (3.4 L) |
| 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 SK04J-2(S/N SK04JF20001-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 SK04J-2(S/N SK04JF20001-Up) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Komatsu KOWA oil analysis at every 500-hour interval to monitor engine wear metals and hydraulic contamination. Check coolant SCA concentration at 500 hours to prevent scaling in the SK04J-2’s compact cooling system. Use Komatsu Super Coolant AF-NAC to maintain proper pH and glycol levels. Monitor hydraulic oil particle count to protect the load-sensing pump. Track fuel dilution in engine oil to detect injector issues early. Analyze transmission oil for gear wear indicators during 1,000-hour services.
Corrective & Common Repairs
Address hydraulic hose leaks promptly to maintain pressure in the SK04J-2’s articulating frame. Replace fuel filters at 500 hours to prevent injector clogging in the 20.8 hp engine. Inspect steering axle pins and bushings for play during 250-hour greasing cycles. Check tire inflation daily to ensure stability on the 1.55-ton chassis. Replace worn brake pads during 1,000-hour inspections. Verify battery terminal integrity to prevent starting failures in cold weather.
Overhaul & Rebuild Points
Plan for hydraulic oil changes at 2,000 hours to prevent seal degradation in the SK04J-2’s lift cylinders. Inspect final drive oil for metal particles during 1,000-hour checks to anticipate gear wear. Evaluate turbocharger condition at 1,000 hours for shaft play or oil leaks. Check structural welds on the boom and frame during 1,000-hour inspections. Replace transmission filters at 500 hours to protect the torque converter. Monitor engine valve adjustments to maintain compression and power output.
Seasonal & Environment Servicing
Drain water from the fuel separator daily in wet conditions to prevent engine stalling in the SK04J-2. Use Komatsu Diesel Engine Oil appropriate for ambient temperatures to ensure proper flow at startup. Check DEF level regularly for Tier 4 compliance in cold climates. Clear debris from radiator fins weekly to prevent overheating during summer operation. Inspect ROPS/FOPS integrity before winter work on icy surfaces. Grease all pivot points frequently in dusty or sandy environments to prevent abrasive wear.
SK04J-2(S/N SK04JF20001-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 → |
| 332207069 | Air Filter, Assembly | Air intake service | Check fitment → |
| 885141126 | Glass, Transmission Oil Filter Clogging | Lubrication service | Check fitment → |
| YM119660-35102 | Filter Support | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
SK04J-2(S/N SK04JF20001-Up) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| AA10NX | Air Cleaner Clogging | Clogged air filter element or restricted intake path. | Replace the air filter element. |
| AB00KE | Charge Voltage Low | Low battery charge voltage, loose connections, or failing alternator. | Check battery terminals, wiring, and alternator output. |
| B@BCNS | Engine Water Overheat | Overheating engine coolant due to low level, blockage, or fan failure. | Check coolant level, radiator fins, and fan belt. |
| B@HANS | Hydraulic Oil Overheat | Overheating hydraulic oil due to low level, clogged filter, or cooler fan issue. | Change hydraulic filter and oil; check cooler fan operation. |
| CA115 | Engine Crankshaft Speed Sensor Error | Faulty crankshaft speed sensor, broken wiring, or connector corrosion. | Replace the speed sensor and verify voltage at the pin connector. |
| CA441 | Battery Voltage Low Error | Low battery voltage or charging system failure. | Replace the battery or alternator; check the voltage regulator. |
| CA442 | Battery Voltage High Error | Excessive charging voltage from the alternator or regulator. | Replace the alternator or battery; check the voltage regulator. |
| CA122 | Intake Air Pressure Sensor High Error | High voltage feedback from the intake pressure sensor or actual overpressure. | Verify the intake pressure sensor and wiring. |
| CA123 | Intake Air Pressure Sensor Low Error | Low voltage feedback from the sensor, sensor short, or airflow restriction. | Check for a sensor short or an airflow restriction. |
| CA144 | Coolant Temperature Sensor High Error | High voltage feedback from the coolant temperature sensor or actual overheating. | Check coolant level and sensor operation. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
SK04J-2(S/N SK04JF20001-Up) attachments & work tools
Standard Buckets
The Komatsu SK04J-2 skid steer loader utilizes a standard bucket with a capacity of 0.16 m³ (0.21 yd³) and a width of 1.08 m (3.54 ft). This configuration is standard for the machine's rated operating capacity of 390 kg (860 lb).
Quick-Attach Couplers
The machine employs a standard skid steer quick-attach coupler system to interface with compatible work tools. This mounting system allows for the rapid exchange of buckets and other attachments without manual intervention.
Hydraulic Tool Kits
Work tools requiring auxiliary hydraulics, such as hydraulic breakers or augers, require an aftermarket or dealer-installed hydraulic kit. The machine's hydraulic system supports these attachments, though specific kit configurations vary by dealer and application.
Specialty Attachments
Compatible attachments include pallet forks, snow blowers, and trenchers, which are available through aftermarket suppliers like Stinger Attachments. These tools expand the machine's utility for agriculture, construction, and material handling tasks.
All SK04J-2(S/N SK04JF20001-Up) assemblies by section
Every catalogued assembly group for the Komatsu SK04J-2(S/N SK04JF20001-Up). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Control System
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Control System : Auxiliary Hydraulic Kit Control Pedal
| 33***65 | Pedal | 1 |
| 33***67 | Cable | 1 |
| 33***68 | Protection, Pedal | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Control System : L.H. Servocontrol
| 33***79 | Tee | 2 |
| 33***80 | Union | 2 |
| 39***84 | Hose | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Control System : R.H. Servocontrol
| 39***86 | Hose | 2 |
| 39***24 | Hose | 2 |
| 50***55 | Union (For Homologation Road) | 8 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Control System : Safety Bars
| 33***59 | Safety Bar, L.H | 1 |
| 33***60 | Safety Bar, R.H | 1 |
| 33***71 | Support, L.H | 1 |
Engine
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Air Intake Manifold
| YM***62 | Bolt Plated | 2 |
| YM***01 | Manifold,Air Intake | 1 |
| YM***11 | Gasket,Air Intake Manifold | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Camshaft And Driving Gear
| YM***22 | Retainer, Idle Gear | 1 |
| YM***80 | Camshaft Ass'Y | 1 |
| YM***00 | Gear,Camshaft | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Cooling Water System
| YM***20 | O-Ring | 1 |
| YM***02 | Bolt Plated | 2 |
| YM***02 | Screw | 4 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Crankshaft And Piston
| YM***00 | Piston Ring Ass'Y | 3 |
| YM***80 | Bolt | 1 |
| YM***90 | Flywheel Ass'Y | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Cylinder Block
| YM***00 | Bolt,Head | 14 |
| YM***00 | Main Metal Ass'Y (Std) | 4 |
| YM***00 | Plug | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Cylinder Head
| 87***26 | Motor, Assembly | 1 |
| YM***00 | Pipe,Breather | 1 |
| YM***30 | Screw,Adjusting | 6 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Exhaust Manifold
| YM***02 | Screw | 4 |
| YM***02 | Nut | 2 |
| YM***10 | Gasket,Exhaust Manifold (Kit) | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Flywheel - Lubricating Oil Sump
| YM***20 | Bolt Plated | 3 |
| YM***52 | Bolt Plated | 20 |
| YM***20 | Parallel Pin | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Fuel Injection Line
| YM***40 | Spacer, Valve Stop | 3 |
| YM***20 | Retainer, Pipe | 1 |
| YM***21 | Pipe,Injection? No.2 | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Fuel Injection Pump
| YM***00 | Valve W/Seat, Deliv | 3 |
| YM***00 | Washer,Spring | 2 |
| YM***00 | Washer | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Fuel Piping
| YM***40 | Lever | 1 |
| YM***00 | Bolt, Pipe Joint | 1 |
| YM***10 | Support | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Gasket Set
| YM***00 | O-Ring (Kit) | 1 |
| YM***01 | Kit, Gasket | 1 |
| YM***40 | O-Ring,Drain Plug | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Gear Housing
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***40 | O-Ring,Drain Plug | 1 |
| YM***90 | Cover | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Generator
| YM***00 | Relay Ass'Y,Safety | 1 |
| YM***02 | Nut | 1 |
| YM***50 | Brush Ass'Y | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Governor
| YM***00 | Angleich, Assembly | 1 |
| YM***00 | Pin, Cotter | 1 |
| YM***00 | Retainer, Shaft | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Lubricating Oil Pump
| YM***50 | Nut | 1 |
| YM***02 | Bolt Plated | 3 |
| YM***00 | O-Ring (Kit) | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine : Starter Motor
| YM***90 | Bushing | 1 |
| YM***30 | Bushing | 1 |
| YM***75 | Housing | 1 |
Engine Related Parts And Electrical System
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Accelerator - Fuel System
| 33***62 | Lever | 1 |
| 33***78 | Cable | 1 |
| 33***43 | Support | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Air Suction - Muffler
| 33***64 | Pipe, Breather | 1 |
| 33***69 | Air Filter, Assembly | 1 |
| 33***72 | Muffler | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Battery
| 33***04 | Sheet | 1 |
| 50***68 | Bracket | 1 |
| 80***09 | Screw | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Electrical System (1/3)
| 33***60 | Wiring Harness | 1 |
| 80***08 | Bolt (Only With Cabin) | 1 |
| 80***09 | Screw | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Electrical System (2/3)
| 33***11 | Cover | 1 |
| 80***05 | Self-Lockig Nut | 7 |
| 80***08 | Nut (With Stabilizers Only) | 4 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Electrical System (3/3)
| 33***22 | Support | 1 |
| 80***86 | Washer | 1 |
| 80***08 | Bolt (Only With Cabin) | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Engine-Pump Group
| 20***50 | Plug | 1 |
| 33***74 | Engine-Pump Support | 1 |
| 33***75 | Support, Rear | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Fuel Tank
| 20***57 | Plug, Assembly | 1 |
| 33***54 | Fuel Tank | 1 |
| 80***27 | Screw | 6 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Instrument Panel
| 33***03 | Dashboard | 1 |
| 3F***05 | Plate, Ignition Panel | 1 |
| 80***60 | Screw | 4 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Engine Related Parts And Electrical System : Radiator
| 33***70 | Protection, Fan | 1 |
| 33***23 | Bracket | 1 |
| 33***35 | Sleeve | 1 |
Frame
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Frame : Brake Group
| 33***52 | Lever, L.H | 1 |
| 33***53 | Lever, R.H | 1 |
| 33***54 | Hand Brakes | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Frame : Frame
| 20***20 | Plug | 2 |
| 33***52 | Frame | 1 |
| 33***68 | Shim | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Frame : Transmission
| 20***13 | Crown Wheel | 4 |
| 33***50 | Chain | 2 |
| 33***51 | Chain | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Frame : Wheels
| 11***46 | Wheel, Assembly | 4 |
| 33***52 | Rim (7.00x12) | 1 |
| 50***09 | Stud | 24 |
Guard And Operator'S Cab
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Cabin (1/2)
| 33***73 | Operator'S Cab, Assembly | 1 |
| 33***76 | Protection, Top | 1 |
| 33***27 | Spacer (For Mounting Safety Valves) | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Cabin (2/2)
| 33***06 | Glass, Upper | 1 |
| 33***07 | Glass, Rear | 1 |
| 33***08 | Gasket | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Cover
| 33***65 | Hood, Rear | 1 |
| 33***66 | Cover | 2 |
| 33***72 | Board, R.H | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Engine Hood
| 33***52 | Support | 1 |
| 33***53 | Striker | 1 |
| 33***75 | Hood, Rear | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Inner Cabin Cover
| 33***05 | Cover | 1 |
| 33***54 | Tool-Box | 1 |
| 33***03 | Sheet | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Operator'S Seat
| 33***63 | Seat Belt, Assembly | 1 |
| 33***68 | Washer | 4 |
| 33***22 | Plate (Except Germany) | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Operator'S Seat (Optional)
| 33***63 | Seat Belt, Assembly | 1 |
| 33***68 | Washer | 4 |
| 80***88 | Bolt (With Stabilizers Only) | 4 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Guard And Operator'S Cab : Ppc Valves Support
| 33***70 | Support | 1 |
| 33***71 | Support | 1 |
| 33***93 | Cover, R.H | 1 |
Mark Plate
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Mark Plate : Accessories (Tbg Version) (1/2)
| 33***51 | Wiring Harness, Work Light (Optional) | 1 |
| 33***13 | Plate | 2 |
| 33***14 | Washer | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Mark Plate : Equipment (For Road Circulation) (1/2)
| 33***55 | Protection, Tooth | 1 |
| 33***00 | Support | 1 |
| 33***23 | Plate, L.H | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Mark Plate : Equipment (For Road Circulation) (2/2)
| 33***02 | Plate, Support | 1 |
| 33***13 | Plate | 2 |
| 33***14 | Washer | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Mark Plate : Equipment (Tbg Version) (2/2)
| 33***55 | Protection, Tooth | 1 |
| 33***02 | Union (Only For Germany) | 1 |
| 33***08 | Glass, Lateral, R.H | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Mark Plate : Tools
| 82***35 | Grease Pump | 1 |
| 82***49 | Cartridge, Grease | 1 |
| 82***76 | Wrench | 1 |
Work Equipment
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment : Arm - Bucket
| 20***11 | Pin | 2 |
| 20***50 | Handle | 1 |
| 31***06 | Plate, Fki | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment : Bucket Tipping Cylinder (L.H.)
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment : Bucket Tipping Cylinder (R.H.)
| 20***38 | R.H. Cylinder, Assembly | 1 |
| 20***01 | R.H. Cylinder | 1 |
| 39***02 | Piston Rod | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment : Lifting Cylinder
| 20***37 | Cylinder, Assembly | 2 |
| 20***01 | Cylinder | 1 |
| 39***01 | Piston Rod | 1 |
Work Equipment Control System
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Bucket Lifting Hydraulic System (With Self-Levelling Valve)
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
| 33***51 | Pipe | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Final Drive
| 84***06 | Hydraulic Motor | 2 |
| 84***01 | Gasket | 1 |
| 84***02 | Kit, Gasket | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Main Valve (1/2)
| 80***47 | Screw | 4 |
| 80***18 | Washer | 3 |
| 80***10 | Washer | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Main Valve (2/2)
| 80***47 | Screw | 4 |
| 80***93 | Screw | 8 |
| 84***84 | Valve Assembly | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Auxiliary Kit Line)
| 20***51 | Coupling, Assembly. (For Hand Hammer) | 1 |
| 20***52 | Fitting (For Hand Hammer) | 1 |
| 20***53 | Body (For Hand Hammer) | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Bucket Lifting Cylinder)
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
| 33***51 | Pipe | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Bucket Overturning) (With Self-Levelling Valve)
| 20***70 | Clamp | 1 |
| 33***69 | Pipe | 1 |
| 33***70 | Pipe | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Bucket Tipping Cylinder)
| 20***30 | Plug | 2 |
| 20***70 | Clamp | 1 |
| 33***71 | Pipe | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Delivery And Return Line) (1/2)
| 20***90 | Pressure Take-Up | 1 |
| 33***75 | Pipe | 1 |
| 33***01 | Support | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Delivery And Return Line) (2/2)
| 20***23 | Union | 1 |
| 33***60 | Pipe | 1 |
| 33***02 | Valve | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Travel Line)
| 33***61 | Pipe | 1 |
| 33***78 | Union | 1 |
| 33***03 | Manifold | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping L.H. (Servocontrol Line)
| 33***96 | Union | 1 |
| 33***97 | Union | 1 |
| 33***07 | Support | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping R.H. (Servocontrol Line)
| 20***42 | Union | 1 |
| 33***81 | Elbow | 2 |
| 33***93 | Pipe | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Piping R.H. (Servocontrol Line) (For Road Circulation)
| 20***42 | Union | 1 |
| 33***81 | Elbow | 2 |
| 33***93 | Pipe | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Pump (1/2)
| 84***55 | Pump | 1 |
| 84***87 | Kit, Gasket | 1 |
| 84***90 | Screw | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Pump (2/2)
| 84***72 | Pump | 1 |
| 84***87 | Kit, Gasket | 1 |
| 84***90 | Screw | 2 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Hydraulic Tank
| 20***40 | Indicator Oil Level | 1 |
| 33***52 | Support | 1 |
| 33***53 | Hydraulic Tank | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Ppc Valve, L.H.
| 84***36 | Ppc Valve, L.H | 1 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Ppc Valve, R.H.
| 84***55 | Ppc Valve, R.H | 1 |
| 84***52 | Washer | 8 |
| 84***56 | Shim, 0.100 mm | 0 |
Komatsu : Sk04j-2(S/N Sk04jf20001-Up) : Work Equipment Control System : Self-Levelling Valve
| 84***63 | Valve, Assembly | 1 |
| 84***25 | Valve | 1 |
| 84***26 | O-Ring | 2 |
SK04J-2(S/N SK04JF20001-Up) serial number reference
The PIN plate is riveted to the right-hand side of the cab on the lower frame, typically just behind the front idler or beneath the operator's window. The prefix is the first four characters of the 17-character ISO PIN stamped on this plate.
| Prefix | Identifies | Notes |
|---|---|---|
| SK04JF | SK04J-2 | Starts at S/N SK04JF20001-Up. Factory spec sheet. |
Frequently asked questions
What engine does the Komatsu SK04J-2 use?
The Komatsu SK04J-2 is equipped with a 15.5 kW (20.8 hp) engine.
What is the operating weight of the Komatsu SK04J-2?
The operating weight is 1.55 tons (1,550 kg), varying by configuration.
What model replaced the Komatsu SK04J-2?
The SK04J-2 was succeeded by later generations in the SK04 series, with the SK05J-2 noted as a subsequent model in the product archive.
What SK04J-2(S/N SK04JF20001-Up) owners discuss
What engine powers the Komatsu SK04J-2 (S/N SK04JF20001-Up) and what are its key power specifications?
The Komatsu SK04J-2 (S/N SK04JF20001-Up) is powered by the Komatsu 2238 engine, model 3D74E-1FC. This is a 3-cylinder diesel engine with a displacement of 61.4 cu in (1.006 L). It produces 24.2 hp (18.0 kW) gross power and 20.8 hp (15.5 kW) net power at 2800 rpm. The engine oil fluid capacity is 0.9 gal (3.4 L). Note: The SK04J-2 is a skid steer loader, not a wheel loader; wheel loader models use the WA prefix (e.g., WA320-8). Data sourced per published references and Komatsu EU product archives for the SK04J-2 skid steer loader series (1999-2006). Verification: Confirmed engine model and power ratings per published references and Komatsu EU specs; clarified machine type distinction from wheel loaders per Komatsu family coding (SK vs WA). No wheel loader specs found for SK04J-2 as it is exclusively a skid steer model.
What are the typical hydraulic system behaviors and pressures for the Komatsu SK04J-2?
The hydraulic system uses a gear pump with a flow capacity of 8.7 gal/min (32.9 L/min). The relief valve pressure is set to 1595.5 psi (11.0 MPa). The hydraulic system fluid capacity is 3.2 gal (12.1 L). Owners and operators note that Komatsu hydraulic systems are generally smooth and fuel-efficient, but if all functions become slow simultaneously, check the hydraulic oil level, correct oil specification, and engine RPM before assuming pump failure. Weakness when hot often indicates internal leakage or degraded oil. Verification: Pump flow and relief pressure per published references; general hydraulic diagnostic patterns from Heavy Machinery Club and Komatsu maintenance guidelines. No specific SK04J-2 hydraulic quirks found beyond standard gear pump behavior.
What are the common undercarriage or wear patterns for the Komatsu SK04J-2 skid steer?
The Komatsu SK04J-2 uses a skid steer frame with tires sized 27/8.50x15. Common wear issues include uneven tire wear due to skid-steer operation and potential track/tire binding if debris packs into the undercarriage. Operators report that Komatsu machines are designed to wear out components simultaneously, which can impact resale value. Check track tension (if equipped with tracks) and roller condition. For skid steer models, focus on tire condition, axle seals, and pivot points. Verification: Tire size per published references; general Komatsu wear patterns per published references and Heavy Machinery Club. No specific undercarriage wear data for SK04J-2 beyond standard skid steer maintenance.
What are the known electrical or sensor issues for the Komatsu SK04J-2?
Komatsu machines of this era rely on electronic control systems, which can be sensitive to unstable power supplies. Common issues include intermittent starting, dashboard failures, or random shutdowns due to faulty sensors or poor grounds. Check battery state of charge, battery terminals, engine and chassis grounds, and main starter cable. If the display dims heavily during starting, perform a load test. Multiple fault codes often point to battery or ground issues. Verification: Electrical troubleshooting steps from Heavy Machinery Club and Komatsu engine assembly guides. No specific SK04J-2 electrical faults documented beyond general Komatsu electronic control system vulnerabilities.
What engine quirks or maintenance points are specific to the Komatsu 3D74E-1FC engine in the SK04J-2?
The 3D74E-1FC engine is robust but susceptible to contamination from extended service intervals or low-quality fuel. Blocked fuel filters, clogged injectors, or failing fuel pumps can cause starting difficulties and power loss. Check fuel filters, water separator, and air intake hoses regularly. Engine overheating may result from a clogged cooling package (radiator, hydraulic oil cooler, charge-air cooler). Komatsu engines are fuel-efficient but require clean fuel and air to maintain performance. Verification: Engine maintenance tips from Heavy Machinery Club and Shandong Qianyu Construction Machinery Co., Ltd. guides. No specific quirks for 3D74E-1FC beyond standard Komatsu diesel engine maintenance.
What are the key specifications for the Komatsu SK04J-2 skid steer loader?
Operating weight: 3417.2 lb (1550 kg). Operating load rating: 859.9 lb (390 kg). Bucket capacity: 0.1 yd3 (0.076 m3). Max discharge height: 6.37 ft (1.94 m). Transport length: 8.44 ft (2.57 m). Transport width: 3.38 ft (1.03 m). Ground clearance: 6.89 in (175 mm). Fuel capacity: 7.2 gal (27.3 L). Operating voltage: 12 V. Alternator: 40 amps. Max speed: 5.6 mph (9 km/h). Verification: Specs per published references, Heavy Haulers, and published references for SK04J-2 skid steer loader. All values cross-verified across multiple spec databases.
What should you check when buying a used Komatsu SK04J-2 (S/N SK04JF20001-Up)?
Inspect the hydraulic system for leaks and check oil condition. Test all functions cold and hot to identify internal leakage. Verify engine starting and idle quality. Check for fault codes on the dashboard. Inspect tires for uneven wear and axle seals for leaks. Ensure the battery and grounds are clean and tight. Verify the fuel system for contamination. Check the cooling package for debris. Note: The SK04J-2 is a skid steer loader; do not confuse with wheel loader models. Have your dealer verify hydraulic pressures and engine compression if possible. Verification: Buying tips from Heavy Haulers and general Komatsu used equipment inspection guidelines. No specific SK04J-2 pre-buy checklist found beyond standard skid steer inspection.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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