Komatsuwheel loadersmall ( - wa120 / sk*)
Komatsu SK04-1(S/N 3220007-Up)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu SK04-1 (S/N 3220007-Up) is a compact four-wheel-drive wheel loader built for the European market from 1997 to 1999, in roughly the 1.5-tonne operating weight class (about 1,520 kg base) with a 0.16 m3 front bucket rated near 390 kg of operating capacity. Engine identity is not settled: parts documentation for this serial range ties engine-overhaul work to a Komatsu 3D72-1 three-cylinder diesel, while several spec listings instead cite a Perkins 103-10 (103.10) three-cylinder, 0.954-litre diesel rated around 15 kW (20.3 hp) - confirm the actual engine fitted from the machine's own dataplate before ordering parts. Either way it is a small, naturally aspirated, mechanically governed diesel with glow-plug cold-start assist and no ECM or fault-code system. The base machine carries a self-leveling front loader bucket, and Komatsu offered a factory rear-mounted backhoe/digging-arm attachment as a configuration option, turning the loader into a compact loader-backhoe for trenching and digging work.
Komatsu revised the optional backhoe arm once during the SK04-1's production run: an earlier arm design covers the early-production serial block, and a later arm design applies from a subsequent production break onward (see the serial number section for the exact breakpoint) - a running production change rather than a separate model. No documented predecessor sits ahead of this serial range; the SK04-1 appears to be the entry point of the SK04 lineage. Komatsu carried the concept forward into the SK04J-2 (S/N SK04JF20001-Up), built 1999-2006 with a different 3D74E-1FC engine, though no source ties that later machine to the SK04-1 as a confirmed direct replacement rather than simply the next model in the same size class. Surviving SK04-1 units are now vintage compact loaders with thin documentation: no official spec-sheet or active owner community exists for this exact serial range, so used-market buyers and parts sourcing lean on the factory parts catalog and the machine's own dataplate rather than published brochures. That scarcity is exactly what keeps correctly identified used units and matched parts valuable to owners of small European construction, agricultural, and landscaping fleets still running this class of loader.
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 SK04-1(S/N 3220007-Up) specifications
Engine
| Engine model | Reported variously as a Perkins 103.10 or a Komatsu 3D72-1 (Yanmar-3TNA72-based), depending on source — confirm the engine actually fitted from the machine's own dataplate before ordering parts. |
| Cylinders | 3-cylinder, in-line, water-cooled diesel (both candidate engines share this layout) |
| Displacement | 0.954 L (58.2 cu in) for the Perkins 103.10 candidate, or approx. 0.879 L for the Komatsu 3D72-1 candidate |
| Rated power (gross) | approx. 15-16 kW (20-21 hp); figure varies slightly by source and engine candidate |
| Emissions tier | Not applicable — pre-emissions-tier design (1990s production) |
Weights
| Operating weight (base loader configuration) | 1,520 kg (3,351 lb) |
| Rated operating capacity | 390 kg (860 lb) |
| Shipping weight / ground pressure | Not published for this exact serial range — verify with dealer |
| Weight with optional rear backhoe attachment | Not published; factory parts catalog documents two production versions of the digging arm across this range (see the serial number section for the exact production break) but no separate operating weight is listed for either |
Dimensions
| Transport length, width, height | Not documented for this exact serial range — verify with dealer or parts book |
| Wheelbase / track gauge | Not documented for this exact serial range |
| Ground clearance | Not documented for this exact serial range |
Performance
| Maximum travel speed | 9 km/h (5.6 mph) |
| Loader bucket capacity (heaped) | 0.16 m³ |
| Loader bucket breakout / lift / dump figures | Not published for this exact serial range/configuration — verify with dealer |
| Rear backhoe digging arm reach/depth | Not documented for this exact serial range. Attachment is a factory option per the parts catalog, offered in two successive digging-arm versions across a mid-production design break (see the serial number section for the exact breakpoint), but no dig depth/reach figures are published for either version |
Service capacities (summary)
| Fuel tank, hydraulic system, engine oil, cooling system | Not documented for this exact serial range/engine pairing — verify with dealer or shop manual |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
SK04-1(S/N 3220007-Up) fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | Approx. 3.1-3.3 L (0.8-0.9 US gal); this is the published figure for the 3-cylinder indirect-injection diesel documented for this loader, not a figure confirmed against the machine's own operation & maintenance manual for this serial range. | Diesel engine oil, API CD/CE service class or later equivalent. SAE 10W-30 in temperate climates, SAE 15W-40 in warm climates; drop to a lighter grade (e.g. 10W or 5W-30) in cold-start conditions below freezing. Change oil and filter on the engine's standard service interval. |
| Cooling system | Approx. 4.7-5.0 L (1.2-1.3 US gal); engine-family figure, not confirmed against the machine's own OMM for this serial range. | Ethylene-glycol based permanent antifreeze/coolant, mixed with clean water to the ratio suited to the expected ambient temperature; use a year-round corrosion-inhibited mix, not plain water. |
| Fuel tank | Not documented for this exact serial range - verify with your dealer or the OMM. | No. 2-D diesel fuel (low-sulfur diesel where required by local regulation). Use a winter-grade or blended fuel in cold climates to avoid fuel waxing. |
| Hydraulic system and tank | Not documented for this exact serial range - verify with your dealer or the OMM. | Anti-wear hydraulic oil. ISO viscosity grade selected by ambient temperature: lighter grade (around ISO VG 32) in cold climates, heavier grade (around ISO VG 46) in temperate to warm climates. |
| Transmission / powertrain compartment | Not documented for this exact serial range - verify with your dealer or the OMM. | Not documented for this exact serial range. Confirm with your dealer whether this loader's drive uses a dedicated gear-oil-filled transmission case or draws from the main hydraulic system before selecting a fluid. |
| Front axle / differential (final drive) | Not documented for this exact serial range - verify with your dealer or the OMM. | Not documented for this exact serial range. Wheel loader axles of this size typically call for a hypoid gear oil (GL-5 type); confirm the exact grade with your dealer before servicing. |
| Rear axle / differential (final drive) | Not documented for this exact serial range - verify with your dealer or the OMM. | Not documented for this exact serial range. Wheel loader axles of this size typically call for a hypoid gear oil (GL-5 type); confirm the exact grade with your dealer before servicing. |
| Grease points (chassis, pivot pins, loader linkage, optional backhoe linkage) | N/A - serviced point by point, not a bulk-fill system. | NLGI No. 2 multipurpose lithium-based EP chassis grease. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Komatsu SK04-1(S/N 3220007-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 SK04-1(S/N 3220007-Up) beyond the schedule
Predictive Maintenance & Fluid Analysis
This loader has no ECM, so condition monitoring is manual. Sample hydraulic oil at each filter change and watch for water or metal fines - the gear-pump circuit feeding the loader and self-leveling linkage, and the backhoe diverter valve on equipped units, is sensitive to contamination. Track engine oil color and smell for fuel dilution, an early sign of injection-pump or injector wear on this small mechanically-governed diesel. Log self-leveling linkage pin play and backhoe response lag; both build gradually and flag wear before a failure interrupts a lift.
Corrective & Common Repairs
Hard cold starting and heavy exhaust smoke usually trace to injection-pump or injector wear, not electronics - this loader has no fault-code system. A weak glow-plug/preheat relay is a common companion complaint. Self-leveling bucket linkage pins and bushings wear loose from decades of tight, full-lock yard turns, letting the bucket tip out of level through the lift; re-pin or bush as needed. If hydraulics cut out or stay live unexpectedly, check the seat/operator-presence interlock before assuming a valve fault. Backhoe-equipped machines commonly need diverter-valve attention as flow sluggishness develops with pump wear.
Overhaul & Rebuild Points
Engine rebuild kits exist for the Komatsu 3D72-1, one of the engine candidates tied to this serial range in parts documentation, covering liners, pistons, rings, bearings, and valve train; budget a full in-frame rebuild once compression and oil consumption drop. Front axle steering knuckles and wheel bearings take the brunt of wear on this loader, since its working life is mostly tight, full-lock turns - inspect and overhaul at high hours rather than waiting for obvious play. Reseal loader and backhoe cylinders at rebuild time, and check pivot-pin bores for elongation before returning to digging work.
Seasonal & Environment Servicing
Cold starts depend on the glow-plug/preheat circuit and battery condition, not any electronic assist; a weak preheat relay is a known cause of hard starting on this engine class. Match hydraulic oil viscosity to season - the small gear-pump circuit feeding the loader and self-leveling linkage can struggle to prime on oil too thick for cold weather. Keep the radiator and engine bay clear of debris in dusty conditions. Verify the seat/operator-presence interlock still cuts hydraulics correctly after seasonal storage; corroded switches and connectors are common on machines this age.
SK04-1(S/N 3220007-Up) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| PKP000007 | Engine Fuel Filter | Fuel system service | Check fitment → |
| 332207069 | Air Filter, Assembly | Air intake service | Check fitment → |
| PKP000018 | Cartridge Engine Oil Filter | Lubrication service | Check fitment → |
| 885141126 | Glass, Transmission Oil Filter Clogging | Lubrication service | Check fitment → |
| PKP000201 | Element | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
SK04-1(S/N 3220007-Up) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| Engine oil pressure warning lamp | Engine lubrication pressure has dropped below the safe minimum. | Low oil level, worn oil pump, clogged oil strainer, or a failed pressure switch. | Stop the engine at once. Check oil level and condition, top up with the specified engine oil grade, then investigate before restarting. |
| Coolant temperature warning lamp | Engine coolant temperature has exceeded the safe operating range. | Low coolant level, clogged radiator fins, a slipping or broken fan belt, or thermostat failure. | Idle down and let the engine cool, then check coolant level, radiator airflow, and belt tension before resuming work. |
| Battery charge (alternator) warning lamp | The alternator is not charging the battery. | Loose or broken fan/alternator belt, faulty alternator, or a wiring fault. | Check belt tension and wiring connections, then test alternator output and battery condition. |
| Glow plug (preheat) indicator lamp | Shows the intake-air preheat cycle for cold starting is active. | Normal cold-start function; a lamp that will not go out or never lights points to a weak glow-plug circuit or relay. | Wait for the lamp to go out before cranking; if it behaves abnormally, check the preheat relay, glow plugs, and wiring. |
| Parking brake warning lamp | Indicates the parking brake is applied or not fully released. | Brake left engaged, linkage out of adjustment, or a switch fault. | Confirm the brake lever position and check linkage adjustment and switch operation. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
SK04-1(S/N 3220007-Up) attachments & work tools
Front loader bucket
Factory-standard general-purpose bucket with a self-leveling linkage that keeps the load level through the lift cycle. Typical capacity for this compact wheel-loader class runs around 0.16 m3 (5.6 cu ft), matched to a rated operating capacity near 390 kg (860 lb).
Pallet forks
Fork-frame tool that pins to the same front loader arm and bucket linkage as the standard bucket, used for pallet and material handling in place of digging or grading work. Sized to the machine's light operating-capacity class rather than heavy-duty fork ratings.
Rear-mounted backhoe / excavator digging arm
Factory-optional rear attachment that turns the loader into a combination loader-backhoe for trenching and excavation. The parts catalog documents two successive versions across the production run: an earlier arm for the early-production serial block and a revised arm from a later production break onward (see the serial number section for the exact breakpoint).
Front attachment mounting
Bucket and fork tools pin directly to the loader arm and bucket linkage (pin-on style), typical of compact wheel loaders in this weight class. No dedicated quick-coupler plate is documented for this serial range, so changeover is a pinned job rather than a lever-operated hitch.
Backhoe hydraulic arrangement
The digging arm runs off the loader's own hydraulic circuit rather than a separate power pack, with dedicated control valving for boom, dipper, and bucket cylinders plus a pair of rear stabilizer legs that ground the machine while digging. Because the arm exists in two parts-book versions, its cylinders and linkage are not interchangeable across the mid-production design break (see the serial number section for the exact breakpoint).
Operator guarding
A ROPS canopy is documented as a factory structure for operator rollover protection on this loader. Cab-versus-open-canopy and FOPS availability vary by configuration; confirm the exact setup for a given unit with a dealer.
All SK04-1(S/N 3220007-Up) assemblies by section
Every catalogued assembly group for the Komatsu SK04-1(S/N 3220007-Up). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Engine
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Alternator And Generator : Unit_01_of_02
| PK***73 | Screw | 2 |
| PK***71 | Connection | 1 |
| PK***62 | Alternator | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Alternator And Generator : Unit_02_of_02
| PK***63 | Lever | 1 |
| PK***65 | Screw | 1 |
| PK***31 | Washer | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Application Miscellaneous And Auxiliaries
| PK***96 | Flange | 1 |
| PK***94 | Seal, Oil | 1 |
| PK***01 | Connection | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Crankshaft - Pistons And Connecting Rods
| PK***24 | Ring Kit (+1.0 mm) | 1 |
| PK***55 | Gear | 1 |
| PK***14 | Kit, Bearing (--0.25 mm) | 0 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Cylinder Block
| 87***16 | Motor, Assembly | 1 |
| PK***31 | Plug | 4 |
| PK***41 | Dowel | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Cylinder Head
| PK***87 | Plug | 6 |
| PK***29 | Insert | 3 |
| PK***25 | Kit, Cylinder Head | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Exhaust Manifold
| PK***39 | Manifold, Exhaust | 1 |
| PK***54 | Stud | 3 |
| PK***05 | Gasket | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Flywheel Housing, Flywheel And Starter Ring
| PK***60 | Screw | 8 |
| PK***62 | Flywheel | 1 |
| PK***63 | Starter Ring | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Front End Drive Input, Fan And Spacer
| PK***02 | Plate | 1 |
| PK***68 | Fan | 1 |
| PK***09 | Key | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Fuel Injection Line (1/2)
| PK***78 | Shim, 0.500 mm | 0 |
| PK***80 | Washer | 2 |
| PK***86 | Injection Pipe N. 1 | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Fuel Injection Line (2/2)
| PK***43 | Gasket | 1 |
| PK***53 | Spring | 1 |
| PK***26 | Nipple | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Gasket Set
| PK***51 | Kit, Gasket | 0 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Gear Drive Auxiliary Drive Options
| PK***05 | Nut | 1 |
| PK***49 | Gasket | 1 |
| PK***80 | O-Ring | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Low Pressure Fuel System (1/2)
| PK***06 | Screw | 2 |
| PK***70 | Washer | 2 |
| PK***07 | Engine Fuel Filter | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Low Pressure Fuel System (2/2)
| PK***67 | Body | 1 |
| PK***73 | O-Ring | 1 |
| PK***76 | Diaphragm | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Lubricating Oil Filter And Breather
| PK***11 | Plug | 1 |
| PK***06 | Nut | 3 |
| PK***49 | Gasket | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Lubricating Oil Filter And Integral Oil Cooler
| PK***15 | Bolt | 2 |
| PK***07 | Washer | 4 |
| PK***18 | Cartridge Engine Oil Filter | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Lubricating Oil Pump And Delivery Housing
| PK***24 | Kit, Repair | 0 |
| PK***59 | Bushing | 1 |
| PK***54 | Gear | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Lubricating Oil Sump
| 33***66 | Pipe | 1 |
| PK***45 | O-Ring | 1 |
| PK***96 | Joint | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Pre-Fuel Filter
| PK***53 | Element | 1 |
| PK***55 | Float | 1 |
| PK***58 | Screw | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Rocker Shaft
| PK***02 | Screw | 6 |
| PK***33 | Lever, R.H | 3 |
| PK***31 | Rocker Shaft | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Starter Motor
| PK***75 | Case | 1 |
| PK***74 | Pinion | 1 |
| PK***84 | Flex Horn | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Timing Gear And Camshaft (1st Part)
| PK***21 | Seal, Oil | 1 |
| PK***35 | Bearing | 1 |
| PK***17 | Screw | 3 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Timing Gear And Camshaft (2nd Part)
| PK***50 | Nut | 2 |
| PK***37 | Spring | 1 |
| PK***39 | Screw | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Engine : Water Pump - Thermostat And Heat Exchanger
| PK***23 | Pulley | 1 |
| PK***02 | Plate | 1 |
| PK***22 | Screw | 4 |
Escavator E20 (From Serial No. 3220007 To 3220749)
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Bucket (Tooth With Bolts Version)
| 20***85 | Bucket, L=300 mm | 1 |
| 20***86 | Bucket, L=400 mm | 1 |
| 20***87 | Bucket, L=250 mm | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Bucket (Welded Tooth Version)
| 20***30 | Bucket, L=250 mm | 1 |
| 20***40 | Bucket, L=300 mm | 1 |
| 20***50 | Bucket, L=400 mm | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Bucket Control Cylinder - Lifting
| 20***08 | Piston Rod | 1 |
| 50***89 | Bushing | 1 |
| 80***20 | Nut | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Dipper Control Cylinder
| 20***52 | Cylinder, Assembly | 1 |
| 50***89 | Bushing | 1 |
| 80***20 | Nut | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Excavation Group
| 50***89 | Bushing | 6 |
| 80***80 | Bolt | 10 |
| 80***24 | Screw | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Excavation Group Hydraulic System
| 80***08 | Nut (With Stabilizers Only) | 1 |
| UE***50 | Hose | 1 |
| UE***51 | Hose | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Fixed Frame And Sliding Plate
| 50***62 | Washer | 2 |
| 80***65 | Bolt | 4 |
| 80***13 | Bolt | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Hydraulic Main Valve (1/3)
| 80***93 | Screw | 2 |
| 80***18 | Washer | 2 |
| 80***09 | Gasket | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Hydraulic Main Valve (2/3)
| 80***93 | Screw | 4 |
| 80***12 | Gasket, Seal | 1 |
| 84***63 | Safety Valve, Assembly | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Hydraulic Main Valve (3/3)
| 80***93 | Screw | 4 |
| 80***12 | Gasket, Seal | 3 |
| 84***84 | Valve Assembly | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Hydraulic Piping Hammer (1/2)
| 20***50 | Plug | 1 |
| 20***70 | Plug (Only For Disconnecting Hammer) | 1 |
| 20***48 | Coupling, Assembly. (For Hammer On Plate And On Excavator) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Hydraulic Piping Hammer (2/2)
| 50***02 | Bushing | 1 |
| 50***03 | Bushing | 1 |
| 50***04 | Bushing | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Main Valve Control Hydraulic System
| 20***51 | Coupling, Assembly. (For Hand Hammer) | 1 |
| 20***52 | Fitting (For Hand Hammer) | 1 |
| 20***53 | Body (For Hand Hammer) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Main Valve Element For Hammer
| 80***93 | Screw | 2 |
| 84***92 | Spring | 1 |
| 84***01 | Kit, Docking, Assembly | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Rotation Group
| 20***07 | Housing | 1 |
| 20***11 | Rotation Group, Assembly | 1 |
| 80***94 | Bolt | 12 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Sliding Plate Hydraulic System With Hydraulic Lock (1/2)
| 50***10 | Union | 1 |
| 50***08 | Elbow (For Hydraulic Lock) | 2 |
| 50***17 | Union | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Sliding Plate Hydraulic System With Hydraulic Lock (2/2)
| 50***45 | Union (For Hydraulic Lock) | 3 |
| 50***08 | Elbow (For Hydraulic Lock) | 2 |
| 50***05 | Union (For Hydraulic Lock) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E20 (From Serial No. 3220007 To 3220749) : Stabilizers Control Cylinder
| 80***18 | Nut | 1 |
| 86***07 | Fitting (Except Germany) | 1 |
| U2***3A | Cap | 1 |
Escavator E22 (From Serial No. 3220756-)
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Bucket (Tooth With Bolts Version)
| 20***85 | Bucket, L=300 mm | 1 |
| 20***86 | Bucket, L=400 mm | 1 |
| 20***87 | Bucket, L=250 mm | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Bucket (Welded Tooth Version)
| 20***30 | Bucket, L=250 mm | 1 |
| 20***40 | Bucket, L=300 mm | 1 |
| 20***50 | Bucket, L=400 mm | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Bucket Control Cylinder
| 86***07 | Fitting (Except Germany) | 1 |
| 86***04 | Fitting (Only For Germany) | 1 |
| UE***64 | Bushing | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Dipper Control Cylinder
| 86***07 | Fitting (Except Germany) | 1 |
| 86***04 | Fitting (Only For Germany) | 1 |
| UE***13 | Piston Rod | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Excavation Group
| 80***82 | Bolt | 12 |
| 80***24 | Screw | 2 |
| 80***92 | Dowel | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Excavation Group Hydraulic System
| 80***08 | Nut (With Stabilizers Only) | 3 |
| UE***76 | Pipe | 1 |
| UE***14 | Protection | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Fixed Frame And Sliding Plate
| 50***62 | Washer | 2 |
| 80***65 | Bolt | 4 |
| 80***13 | Bolt | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Hydraulic Main Valve (1/3)
| 80***18 | Washer | 3 |
| 80***09 | Gasket | 1 |
| 80***12 | Gasket, Seal | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Hydraulic Main Valve (2/3)
| 80***12 | Gasket, Seal | 2 |
| 84***92 | Spring | 2 |
| 84***93 | Cover | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Hydraulic Main Valve (3/3)
| 80***12 | Gasket, Seal | 2 |
| 84***63 | Safety Valve, Assembly | 2 |
| 84***84 | Valve Assembly | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Hydraulic Piping Hammer (1/2)
| 20***49 | Fitting (For Hammer On Plate And On Excavator) | 1 |
| 20***50 | Body (For Hammer On Plate And On Excavator) | 1 |
| 20***52 | Fitting (For Hand Hammer) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Hydraulic Piping Hammer (2/2)
| 50***10 | Union | 1 |
| 50***47 | Union (For Hand Hammer) | 1 |
| 82***20 | Point | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Lifting Control Cylinder
| 86***07 | Fitting (Except Germany) | 1 |
| 86***04 | Fitting (Only For Germany) | 1 |
| U2***0A | Cap | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Main Valve Control Hydraulic System
| 20***51 | Coupling, Assembly. (For Hand Hammer) | 1 |
| 20***52 | Fitting (For Hand Hammer) | 1 |
| 20***53 | Body (For Hand Hammer) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Main Valve Element For Hammer
| 80***93 | Screw | 2 |
| 84***92 | Spring | 1 |
| 84***01 | Kit, Docking, Assembly | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Main Valve Support
| 80***46 | Bolt | 8 |
| 80***48 | Bolt | 1 |
| 80***97 | Screw | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Rotation Group
| 20***07 | Housing | 1 |
| 20***11 | Rotation Group, Assembly | 1 |
| 80***94 | Bolt | 12 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Sliding Plate Hydraulic System With Hydraulic Lock
| 50***10 | Union | 1 |
| 50***08 | Elbow (For Hydraulic Lock) | 2 |
| 50***17 | Union | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Escavator E22 (From Serial No. 3220756-) : Stabilizers Control Cylinder
| 80***18 | Nut | 1 |
| 86***07 | Fitting (Except Germany) | 1 |
| U2***3A | Cap | 1 |
Machine And Optional Devices
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Accelerator - Fuel System
| 20***57 | Plug, Assembly | 1 |
| 33***62 | Lever | 1 |
| 33***21 | Support | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Air Filter - Exhaust Silencer
| 33***50 | Muffler | 1 |
| 33***61 | Support | 1 |
| 33***64 | Pipe, Breather | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Arm - Bucket
| 20***11 | Pin | 2 |
| 20***50 | Handle | 1 |
| 31***06 | Plate, Fki | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Brake Group
| 33***52 | Lever, L.H | 1 |
| 33***53 | Lever, R.H | 1 |
| 33***54 | Hand Brakes | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Control Cylinder
| 20***38 | R.H. Cylinder, Assembly | 1 |
| 20***39 | R.H. Cylinder, Assembly | 1 |
| 20***01 | R.H. Cylinder | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Lifting Hydraulic System (With Self-Levelling Valve) : Unit_01_of_02
| 20***90 | Pressure Take-Up | 1 |
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Lifting Hydraulic System (With Self-Levelling Valve) : Unit_02_of_02
| 20***90 | Pressure Take-Up | 1 |
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Lifting Hydraulic System (With Self-Levelling Valve) (1/2)
| 20***90 | Pressure Take-Up | 1 |
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Lifting Hydraulic System (With Self-Levelling Valve) (2/2)
| 33***06 | Tie-Rod | 1 |
| 33***07 | Joint | 1 |
| 33***08 | Support | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Overturning Hydraulic System (With Self-Levelling Valve) : Unit_01_of_02
| 20***70 | Clamp | 1 |
| 33***54 | Pipe | 1 |
| 33***55 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Bucket Overturning Hydraulic System (With Self-Levelling Valve) : Unit_02_of_02
| 20***70 | Clamp | 1 |
| 33***69 | Pipe | 1 |
| 33***70 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Cabin (1/2) : Unit_01_of_02
| 33***51 | Protection, Top | 1 |
| 33***60 | Operator'S Cab, Assembly | 1 |
| 33***69 | Retainer | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Cabin (1/2) : Unit_02_of_02
| 33***27 | Spacer (For Mounting Safety Valves) | 2 |
| 33***64 | Cover | 2 |
| 33***06 | Gasket, R.H | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Cabin (2/2)
| 33***62 | Protection | 1 |
| 33***63 | Seat Belt, Assembly | 1 |
| 33***65 | Hood, Rear | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Cabin (2/2) (Only For Germany)
| 33***62 | Protection | 1 |
| 33***63 | Seat Belt, Assembly | 1 |
| 33***65 | Hood, Rear | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Electrical System (2/2) : Unit_01_of_02
| 33***22 | Support | 1 |
| 33***55 | Ppc Valve, L.H | 1 |
| 33***58 | Knob | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Electrical System (2/2) : Unit_02_of_02
| 33***58 | Knob | 1 |
| 33***59 | Horn, Wiring | 1 |
| 33***37 | Support | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Engine-Pump Group
| 33***55 | Engine-Pump Support | 1 |
| 33***57 | Support | 1 |
| 33***58 | Joint | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Equipment (Germany Version)
| 33***58 | Support | 1 |
| 80***47 | Bolt | 1 |
| 80***00 | Screw (Only For Germany) | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Equipment Unloading Kit
| 20***48 | Coupling, Assembly. (For Hammer On Plate And On Excavator) | 1 |
| 20***49 | Fitting (For Hammer On Plate And On Excavator) | 1 |
| 20***50 | Body (For Hammer On Plate And On Excavator) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Frame
| 20***20 | Plug | 2 |
| 33***51 | Frame | 1 |
| 33***68 | Shim | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Main Valve (1/2)
| 80***93 | Screw | 6 |
| 80***18 | Washer | 4 |
| 80***09 | Gasket | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Main Valve (2/2)
| 80***93 | Screw | 12 |
| 84***18 | Control Valve, Assembly | 1 |
| 84***84 | Valve Assembly | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Bucket Lifting Cylinder)
| 20***90 | Pressure Take-Up | 1 |
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Bucket Lifting Cylinder) (1/2)
| 20***90 | Pressure Take-Up | 1 |
| 20***70 | Clamp | 2 |
| 33***50 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Bucket Lifting Cylinder) (2/2)
| 33***06 | Tie-Rod | 1 |
| 33***07 | Joint | 1 |
| 33***08 | Support | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Bucket Tipping Cylinder)
| 20***30 | Plug | 2 |
| 20***70 | Clamp | 1 |
| 33***54 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Bucket Tipping Cylinder) (1/2)
| 20***30 | Plug | 2 |
| 20***70 | Clamp | 1 |
| 33***71 | Pipe | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Bucket Tipping Cylinder) (2/2)
| 39***52 | Hose | 1 |
| 39***41 | Hose | 1 |
| 50***12 | Union | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Delivery And Return Line) (1/2)
| 20***40 | Indicator Oil Level | 1 |
| 33***01 | Support | 1 |
| 33***05 | Hydraulic Tank | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Piping (Delivery And Return Line) (2/2)
| 33***02 | Valve | 1 |
| 39***71 | Hose | 1 |
| 39***52 | Hose | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Pump (1/2)
| 80***24 | Snap Ring | 1 |
| 80***16 | Snap Ring | 1 |
| 80***30 | Ring, Snap | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic Pump (2/2)
| 80***24 | Snap Ring | 1 |
| 80***30 | Ring, Snap | 1 |
| 80***62 | Ring, Snap | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Hydraulic System Boom Loader Kit
| 20***51 | Coupling, Assembly. (For Hand Hammer) | 1 |
| 20***52 | Fitting (For Hand Hammer) | 1 |
| 20***53 | Body (For Hand Hammer) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Instrumentation : Unit_01_of_02
| 33***50 | Dashboard | 1 |
| 35***53 | Wrench | 2 |
| 80***60 | Screw | 4 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Instrumentation : Unit_02_of_02
| 33***50 | Dashboard | 1 |
| 80***60 | Screw | 4 |
| 81***87 | Washer (Optional) | 4 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Lifting Control Cylinder
| 20***37 | Cylinder, Assembly | 2 |
| 20***01 | Cylinder | 1 |
| 39***01 | Piston Rod | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Pedals Locking
| 33***89 | Outline | 1 |
| 33***53 | Locking Device | 1 |
| 33***56 | Support | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Pedals Unit
| 20***23 | Pedal, L.H | 1 |
| 33***50 | Central, Pedal | 1 |
| 33***51 | Support, R.H | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Radiator Group
| 33***63 | Water Radiator, Assembly | 1 |
| 33***70 | Protection, Fan | 1 |
| 33***00 | Sleeve | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Rear Hood
| 33***52 | Support | 1 |
| 33***53 | Striker | 1 |
| 33***61 | Hood, Rear | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Road Homologation - Work Light (1/2)
| 33***00 | Plate, Support | 1 |
| 33***03 | Support (Version A) | 1 |
| 33***13 | Plate | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Road Homologation - Work Lights (2/2)
| 20***22 | Protection | 1 |
| 33***00 | Support | 1 |
| 33***58 | Support | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Safety Valve (1/2)
| 20***50 | Clamp | 1 |
| 33***50 | Electric Wiring, Assembly | 1 |
| 33***51 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Safety Valve (2/2)
| 33***55 | Pipe | 1 |
| 33***56 | Pipe | 1 |
| 33***57 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Self-Levelling Valve : Unit_01_of_02
| 84***01 | Valve, Assembly | 1 |
| 84***01 | Plug | 3 |
| 84***02 | Spring | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Self-Levelling Valve : Unit_02_of_02
| 84***63 | Valve, Assembly | 1 |
| 84***25 | Valve | 1 |
| 84***26 | O-Ring | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Shovel Connection Devices
| 33***50 | Support, R.H | 1 |
| 33***51 | Support, L.H | 1 |
| 33***52 | Connecting Rod | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Tools - Mark Plate
| 30***38 | Plate ?Fai Komatsu? | 2 |
| 33***50 | Mark Plate (I) | 1 |
| 33***51 | Mark Plate (I) | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Transmission
| 20***13 | Crown Wheel | 4 |
| 33***50 | Chain | 2 |
| 33***51 | Chain | 2 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Transmission Hydraulic Motor
| 84***06 | Hydraulic Motor | 2 |
| 84***01 | Gasket | 1 |
| 84***02 | Kit, Gasket | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Transmission Hydraulic System
| 20***90 | Pressure Take-Up | 1 |
| 33***60 | Pipe | 1 |
| 33***61 | Pipe | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Travel Control Lever
| 33***50 | Support, R.H | 1 |
| 33***51 | Support, L.H | 1 |
| 33***52 | Lever, L.H | 1 |
Komatsu : Sk04-1(S/N 3220007-Up) : Machine And Optional Devices : Wheels
| 33***50 | Rim (7.00x12) | 4 |
| 33***51 | Rim (5jx12) (Optional) | 4 |
| 33***52 | Rim (7.00x12) | 4 |
SK04-1(S/N 3220007-Up) serial number reference
Serials in this range are read as a plain sequential production number (e.g. 3220007) with no letter prefix, so a higher number simply means later production. If the rear digging-arm/excavator attachment is fitted, compare the machine's serial against the 3220749/3220756 break to identify which version is installed (E20 vs E22). Exact PIN plate placement is not independently documented for this model online; confirm plate location and full number directly on the machine or with your Komatsu dealer, and check for the number restamped into the frame near the plate as a backup.
| Prefix | Identifies | Notes |
|---|---|---|
| 3220007-Up | SK04-1 compact 4WD wheel loader, self-leveling front loader bucket, optional rear-mounted backhoe/digging-arm attachment | Plain numeric serial run for this range, no letter prefix. The optional rear digging-arm/excavator attachment was fitted in two versions within this range per the factory parts catalog: earlier design (E20) on S/N 3220007 to 3220749, later design (E22) from S/N 3220756-Up. This is a running production/spec change within one serial range, not a separate serial-prefix family. No additional prefixes or sibling ranges tied to this exact model found; a same-numbered SK04-1 catalog entry at S/N 1001-Up belongs to a different chassis/catalog family and is not part of this range. |
Frequently asked questions
What engine does the Komatsu SK04-1 (S/N 3220007-Up) use?
Sources disagree. Parts documentation for this serial range ties engine-overhaul components to a Komatsu 3D72-1 three-cylinder diesel, while several spec listings instead cite a Perkins 103-10 (103.10) three-cylinder, 0.954-litre diesel rated around 15 kW (20.3 hp). Both are small, mechanically governed, pre-electronic diesels with glow-plug cold-start assist and no ECM or fault codes. Confirm the actual engine fitted from the machine's own dataplate before ordering engine parts.
What is the operating weight of the Komatsu SK04-1?
About 1.5 tonnes (roughly 1,520 kg in base loader configuration, varying by source and configuration), with a 0.16 m3 front bucket rated for approximately 390 kg of operating capacity. Adding the factory rear backhoe/digging-arm attachment changes the working weight and balance point; no separate published weight figure exists for backhoe-equipped units, so confirm the as-configured weight for any specific machine.
What replaced the Komatsu SK04-1?
No source documents a confirmed, named direct replacement for the SK04-1. The closest documented follow-on in the same size class is the Komatsu SK04J-2 (S/N SK04JF20001-Up), built 1999-2006 with a different 3D74E-1FC engine; treat it as the plausible next generation in the lineage rather than a verified direct replacement.
What SK04-1(S/N 3220007-Up) owners discuss
Is there active online community discussion about the SK04-1 specifically, and what should I keep in mind reading around online?
Very little exists. This is a rare, late-1990s European-market compact loader with no active owner community online. General heavy-equipment forums carry no dedicated threads on the SK04-1, and most search results are parts listings or generic spec pages rather than firsthand operator accounts. Several of those spec listings even mislabel the machine as a skid-steer, which is incorrect for this serial range — it is a compact 4-wheel-drive wheel loader with a self-leveling front bucket and an optional rear backhoe/digging-arm attachment. The notes below draw on well-documented patterns for small, mechanically-governed diesel loaders of this size and era rather than direct SK04-1 testimonials, since none could be verified for this exact model.
How does the hydraulic system and self-leveling front bucket typically behave, and what wears out first?
Loaders of this class run a simple gear-pump hydraulic circuit feeding the lift and tilt functions and, where fitted, a mechanical self-leveling linkage (rods and bellcranks, not electronic) that keeps the bucket angle constant through the lift cycle. The linkage pins and bushings are usually the first thing to wear loose; once they do, the bucket stops staying level as the boom rises and needs re-pinning or bushing replacement. Cylinder seals and hose fittings are the other common source of slow external leaks after two to three decades of service. Because worn self-leveling linkage can let a raised load tip unexpectedly, have your dealer verify the linkage and cylinder condition before relying on it for lifting work.
What wear patterns show up in the axles, wheels, and steering on a machine this size and age?
This is a wheeled machine, not tracked, so wear concentrates in the front axle and steering knuckles, wheel bearings, and tires rather than track chain and rollers. Compact loaders this size spend most of their working life doing tight, full-lock turns in yards and around buildings, which accelerates wear on steering knuckle pins and wheel bearings and produces uneven, scrubbed front tire wear. Play in the steering linkage and front hubs is common on a machine this age and is not on its own a sign of abuse, but it should be budgeted for in any purchase or overhaul.
What engine quirks come with this series, and what should I expect from a diesel of this era?
This series is generally documented with a small, naturally aspirated, mechanically-governed diesel in the 15 kW (20 hp) class, in line with other compact loaders of this size and period. Mechanically-governed engines of this type are known for stiff cold starting when the glow-plug/preheat circuit is weak, gradually declining power and increasing smoke as the injection pump and injectors wear, and a fixed, fairly narrow governor band rather than an adjustable electronic torque curve. Fuel-system cleanliness (tank, lift pump, filters) tends to matter more for reliable starting on an engine like this than anything electronic.
What electrical or sensor issues are common on machines of this vintage and class?
Machines of this vintage and class carry minimal electronics: a basic charging circuit, a glow-plug/preheat relay, gauges, and typically a seat or operator-presence safety interlock that disables loader (and backhoe, if fitted) hydraulics when the seat is unoccupied. The common gremlins on machines this age are corroded grounds and connectors, a worn or misadjusted seat switch that intermittently kills hydraulic function, and a tired alternator/regulator causing slow cranking or dim lighting. Because a faulty safety interlock can mask an unsafe condition — hydraulics staying live with the seat empty, or cutting out unexpectedly mid-lift — have your dealer verify the interlock wiring and operation rather than bypassing it.
What about the rear backhoe/digging-arm attachment — anything worth knowing for machines set up this way?
On loaders in this class fitted with an optional rear digging arm, the hydraulic circuit switches between loader and backhoe duty, usually through a diverter valve. On machines this age, marginal pump flow and worn valve spools are the typical complaint, with backhoe functions feeling sluggish compared to the loader end once the pump has years of wear on it. Attachment mounting hardware and stabilizer pins are also worth checking for play, since digging work puts more side-load on the chassis than straight loader work. Given the risk of unexpected boom or bucket movement from a worn diverter valve, have your dealer verify the switching valve and backhoe circuit before working near or under a raised arm.
What should I check when buying a used SK04-1(S/N 3220007-Up)?
Confirm the serial number falls in the 3220007-and-up range before sourcing parts or manuals, since Komatsu revised this model partway through production and specs and parts do not carry over cleanly across serial breaks. Walk the machine for self-leveling linkage pins and bushings, cylinder seal leaks, front wheel bearing and steering play, and, if backhoe-equipped, the diverter valve and stabilizer pins. Start the engine cold and watch for hard starting or heavy smoke, which points to injection-pump or compression wear on a machine this age. Because this is an obscure, out-of-production model, confirm realistic parts availability before committing, since sourcing can be slower and more expensive than for mainstream compact loaders.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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