Komatsuengine(no series)
Komatsu 4D94E-1A(S/N 00101-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 4D94E-1A (S/N 00101-UP) is a compact 4-cylinder, water-cooled diesel engine built around roughly 2.8 liters (169 cu in) of displacement, with a 94 mm bore and 100 mm stroke. It is naturally aspirated and mechanically governed, with governed output reported anywhere from about 29.5 kW (40 hp) in compact-dozer service up to roughly 43 kW (58 hp) in other applications, depending on the host machine's fuel and governor setting. Dry weight runs approximately 220-230 kg before accessories. Komatsu fitted this engine across its small equipment lines through the 1990s: the FD20, FD20T, FD25, and FD30 series forklifts, the WA65-3, WA65PT-3, WA75-3, WA90-3, and WA115-3 compact wheel loaders, and the D20P-7 and D21A-7-M crawler dozers. Flywheel housing, accessory drive, and governor setup vary by host machine to match torque-converter, hydrostatic, or power-shift transmissions.
The -1A suffix and 00101-UP serial break mark a production revision within Komatsu's original 94-series small diesel line, distinct from the earlier base 4D94E and from later low-emission 4D94LE and 4D94LE-2 variants that eventually replaced it as EPA Tier 2 rules tightened. Because this block powered forklifts, wheel loaders, and dozers side by side for most of a decade, it remains one of the more common Komatsu compact diesels to find in salvage and rebuild channels today. Aftermarket rebuild kits and internal components for this displacement class remain widely available, which keeps parts sourcing straightforward for this engine today. For owners of aging FD-series forklifts or WA65/WA75-class loaders, that shared parts base keeps overhaul costs more reasonable than on a single-application engine.
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 4D94E-1A(S/N 00101-UP) specifications
Engine
| Model / generation | 4D94E-1A (S/N 00101-UP), naturally aspirated version of the 94E engine family. Turbocharged siblings 4D94E-1AB and 4D94E-1AH share the same base block but are separate variants. |
| Configuration | Vertical, in-line 4-cylinder, water-cooled, 4-cycle diesel, direct injection |
| Bore x stroke | 94 mm x 100 mm (3.70 in x 3.94 in) |
| Displacement | 2.776 L (2,776 cc / 169 cu in) |
| Aspiration | Naturally aspirated (non-turbo) |
| Gross power | 48 kW (65 hp) at 2,450 rpm (SAE gross rating as installed) |
| Net / certified power | 44.1-44.6 kW (59-60 hp) at 2,450 rpm (EPA-certified continuous rating per engine emission label) |
| Emissions certification | Certified to 2004-model-year U.S. EPA regulations for large nonroad compression-ignition engines; certified to run on US2D commercial diesel fuel |
Weights
| Engine dry weight | Approx. 223 kg (492 lb) — figure drawn from a single aftermarket engine-data compilation, not independently cross-verified; confirm with your dealer for this exact serial range |
| Operating / shipping weight | Not applicable — this is a standalone engine, not a complete machine |
| Ground pressure | Not applicable to a bare engine |
Dimensions
| Engine block (L x W x H) | Approx. 720 mm x 508 mm x 689 mm (28.3 in x 20.0 in x 27.1 in) — figure drawn from a single aftermarket engine-data compilation, not independently cross-verified; confirm with your dealer |
| Transport / chassis dimensions | Not applicable — engine only, no wheelbase, track gauge, or ground clearance to report |
Performance
| Rated engine speed | 2,450 rpm |
| Idle speed | 675-725 rpm (as installed in Komatsu diesel forklift applications) |
| Governed maximum speed | 2,650-2,750 rpm |
| Compression pressure | 2.84-3.04 MPa (412-441 psi), minimum 2.34 MPa (340 psi) at 250 rpm cranking speed |
| Fuel injection order | 1-3-4-2 (No. 1 cylinder on flywheel side) |
| Fuel injection timing | 6 degrees ATDC |
| Fuel injection pressure | 12.75 MPa (1,850 psi) |
| Rated torque | Not documented for this exact bore/stroke configuration in available sources — verify with your dealer. (A torque figure exists for the related 92 mm-bore 4D94LE variant but does not apply to this 94 mm-bore 4D94E-1A.) |
| Machine-installed travel speed / gradeability | Not applicable to the engine itself — varies by host machine (diesel forklifts, compact dozers, wheel loaders); not attributed here to avoid cross-machine contamination |
Service capacities (summary)
| Engine oil (with filter) | 7.6 L (8.0 US qt) |
| Cooling system | 9.2 L (2.43 US gal) |
| Fuel tank | Not applicable — the engine has no onboard fuel tank; capacity depends on the host machine |
| Hydraulic system | Not applicable — this is an engine, not a hydraulic machine |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
4D94E-1A(S/N 00101-UP) fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (oil pan, with filter) | approx. 7 to 7.5 L (1.8 to 2.0 US gal) per the engine-family service data; exact figure for this serial range not separately published — verify with dealer before a full oil-and-filter change | Komatsu Genuine diesel engine oil, selected by ambient temperature per the OMM chart: EO10W30-DH for cooler ranges, EO15W40-DH for warmer ranges (API CD/CE or higher equivalent accepted where genuine oil is unavailable) |
| Cooling system (engine water jacket) | approx. 4 L engine-only per the engine-family service data; total system capacity (with radiator) runs higher and is set by the host installation — comparable small Komatsu crawler-dozer installations in this engine class fall in the 10 to 14 L (2.6 to 3.7 US gal) range, so treat this as a bracket, not a fixed figure | Komatsu Genuine AF-NAC super coolant (or an equivalent ethylene-glycol antifreeze/anti-corrosion coolant meeting ASTM D3306/D4985), mixed to the ratio suited for local ambient/freeze conditions |
| Fuel | no tank on the bare engine — fuel tank size is set by the host machine (dozer, wheel loader, or forklift chassis) and is not part of the engine's own fluid chart | Diesel fuel, cetane number 45 minimum, equivalent to ISO 8217 DMA or BS 2869 A1/A2 grade |
| Grease (general engine-mounted linkage/accessory points) | apply as needed at listed grease points; no bulk reservoir | NLGI No. 2 multipurpose lithium-based grease (Komatsu Genuine G2-LI grease or equivalent) |
| Transmission / hydraulic / final drive / axle systems | not applicable to the bare engine — this engine is fitted across multiple host machines (small crawler dozers, WA65/WA75-class wheel loaders, and forklift trucks), each with its own transmission, hydraulic, and final-drive/axle fluid chart set by the chassis OMM, not the engine OMM | refer to the specific host machine's own operation and maintenance manual for these systems |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Komatsu 4D94E-1A(S/N 00101-UP) maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
Servicing the 4D94E-1A(S/N 00101-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Track oil condition closely on this naturally aspirated block since there's no turbo to mask early wear signs. Watch coolant for oil intrusion at the water pump seal, a known wear point on high-hour units. On forklift installs, monitor injection pump and governor response for hunting or hesitation under load, an early sign of internal wear. Sample fuel filters for water and sediment more often on wheel loaders and dozers running in wet yards or quarries.
Corrective & Common Repairs
Common failures on this engine include starter and alternator wear from repeated cold starts on forklifts, water pump seal leaks, and injector tip wear from inconsistent fuel quality. Fuel lift pump diaphragm failure shows up as hard starting or power loss under load. On dozer and wheel loader installs, check engine mount bushings and flywheel housing bolts, which loosen under sustained vibration and track shock loading.
Overhaul & Rebuild Points
At top-end rebuild, check cylinder liner wear and piston ring end gap against factory limits before reusing components. Inspect valve seats for recession, a common issue on high-hour naturally aspirated diesels of this vintage. Rebuild kits and reground crankshafts for this displacement class are widely available industry-wide, which helps keep overhaul costs down on FD-series forklifts and WA65/WA75-class loaders.
Seasonal & Environment Servicing
Check the cold-start/glow system before winter operation, since this naturally aspirated engine relies on it for reliable starts below freezing. Verify coolant freeze protection and hose condition ahead of cold weather. In dusty or high-debris environments common to dozer and wheel loader work, clean radiator fins and air cleaner elements more often than the standard interval. Drain the fuel filter/water separator more frequently in humid or high-condensation climates.
4D94E-1A(S/N 00101-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM129901-55800 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| (YM129901-55800) | Fuel Filter Ass'Y,(See Fig.A4110-B0a2) | Fuel system service | Check fitment → |
| YM129470-55610 | Body, Fuel Filter | Fuel system service | Check fitment → |
| YM129910-55600 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| YM119005-12571 | Element,Inner | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
4D94E-1A(S/N 00101-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| Oil Pressure Warning Lamp (red oil-can symbol) | Engine oil pressure has dropped below the switch threshold | Low oil level, worn oil pump or bearings, clogged oil filter, or oil pressure switch failure | Stop the engine immediately, check oil level, then verify actual pressure with a mechanical gauge before restarting |
| Coolant Temperature Warning Lamp (red thermometer symbol) | Engine coolant temperature has exceeded the safe operating threshold | Low coolant level, blocked or dirty radiator, failed thermostat, or a loose/broken fan belt | Idle down and shut off once safe, let the engine cool, then check coolant level, belt condition, and radiator airflow |
| Charge Warning Lamp (red battery symbol) | Alternator is not charging the battery | Worn, glazed, or broken alternator drive belt, faulty alternator, or a loose/corroded wiring connection | Check belt tension and condition first, then test alternator output and battery terminal connections |
| Air Cleaner Restriction Indicator (pop-up/visual gauge) | Intake air filter element is restricted beyond the allowable limit | Clogged or saturated air filter element from dust or debris ingestion | Inspect and clean or replace the air filter element, then reset the restriction indicator |
| Preheat/Glow Indicator Lamp (coil symbol, cold-start models) | Intake air preheat circuit is energized for cold starting | Normal during cold-start warm-up; if it stays lit or fails to energize, points to a stuck preheat relay, faulty timer, or failed heater element | If lamp behaves abnormally, check the preheat relay, timer, and heater element continuity |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
All 4D94E-1A(S/N 00101-UP) assemblies by section
Every catalogued assembly group for the Komatsu 4D94E-1A(S/N 00101-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Engine
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Air Cleaner (For Trimming Dozer)(#02611-)
| YM***40 | Valve,Unloader | 1 |
| YM***30 | Pan,Dust | 1 |
| YM***22 | Screw | 6 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Air Cleaner (For Trimming Dozer? Sandy And Dusty Spec.)(#00101-02610)
| YM***02 | Bolt Plated | 4 |
| YM***40 | Valve,Unloader | 1 |
| YM***10 | Hose | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Air Cleaner(#00101-02610)
| YM***02 | Bolt Plated | 4 |
| YM***40 | Valve,Unloader | 1 |
| YM***10 | Hose | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Air Cleaner(#02611-)
| YM***01 | Air Cleaner Ass'Y | 1 |
| YM***40 | Valve,Unloader | 1 |
| YM***30 | Pan,Dust | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Air Intake Manifold
| YM***02 | Screw | 2 |
| YM***00 | Manifold,Air Intake | 1 |
| YM***21 | Gasket (Kit) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator (40a) (Inner Parts)(#00101-02610)
| YM***50 | Brush Ass'Y | 1 |
| YM***00 | Retainer,Bearing | 1 |
| YM***70 | Diode Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator (40a) (Inner Parts)(#02611-)
| YM***20 | Rear Bracket Ass'Y | 1 |
| YM***30 | Front Bracket Ass'Y | 1 |
| YM***00 | Rotor Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator (60a) (Inner Parts) (With Air Conditioner)(#02611-)
| YM***00 | Stator Ass'Y | 1 |
| YM***12 | Alternator A. (60a) | 1 |
| YM***02 | Rotor Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator (60a) (Inner Parts) (With Air Conditioner? Poor Fuel Type And Cold Terrain Spec.)(#00101-02610)
| YM***70 | Rectifier Ass'Y | 1 |
| YM***80 | Diode Ass'Y | 1 |
| YM***10 | Alternator A. (60a) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator (80a) (Inner Parts)(#02611-)
| YM***01 | Cover | 1 |
| YM***60 | Wire | 1 |
| YM***00 | Starter Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator And Mounting (25a) (For Trimming Dozer)(#02611-)
| YM***40 | Distance Piece | 1 |
| YM***40 | Screw | 1 |
| YM***01 | Alternator A. (25a) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator And Mounting (25a) (For Trimming Dozer? Sandy And Dusty Spec.)(#00101-02610)
| YM***00 | Alternator A. (25a) | 1 |
| YM***40 | Distance Piece | 1 |
| YM***02 | Screw | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator And Mounting (40a)(#00101-02610)
| YM***02 | Nut | 1 |
| YM***52 | Screw | 1 |
| YM***30 | Adjuster, Belt | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator And Mounting (40a)(#02611-)
| YM***40 | Screw | 1 |
| YM***60 | Nut | 1 |
| YM***30 | Adjuster, Belt | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator And Mounting (60a) (With Air Conditioner)(#02611-)
| YM***40 | Distance Piece | 1 |
| YM***40 | Screw | 1 |
| YM***02 | Screw | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Alternator And Mounting (60a) (With Air Conditioner? Poor Fuel Type And Cold Terrain Spec.)(#00101-02610)
| YM***40 | Distance Piece | 1 |
| YM***02 | Screw | 1 |
| YM***30 | Adjuster, Belt | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Block Heater (Cold Terrain Spec.)
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Camshaft And Tappet
| YM***00 | Tappet Rod | 8 |
| YM***50 | Bearing, Thrust | 1 |
| YM***80 | Camshaft Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Crankshaft
| YM***90 | Pulley | 1 |
| YM***50 | Pulley | 1 |
| YM***20 | Parallel Pin | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Crankshaft (For Trimming Dozer)
| YM***50 | Pulley | 1 |
| YM***20 | Parallel Pin | 1 |
| YM***00 | Crankshaft Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Crankshaft (With Air Conditioner)
| YM***60 | Pulley | 1 |
| YM***30 | O-Ring (Kit) | 1 |
| YM***20 | Parallel Pin | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Cylinder Block
| YM***00 | Main Metal Ass'Y (Std) | 5 |
| YM***50 | Plug | 1 |
| YM***40 | Main Metal Ass'Y,0.25mm (Us) | 5 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Cylinder Block Accsessory
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***90 | Valve,Water Drain | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Cylinder Head
| YM***80 | Retainer, Spring | 8 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***00 | Plug | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Dipstic
| YM***00 | Gauge,Oil | 1 |
| YM***10 | Guide,Oil Gauge | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Drive Gear
| YM***00 | Idle Gear Ass'Y | 1 |
| YM***00 | Gear Ass'Y,Hydraulic Pump | 1 |
| YM***00 | Gear,Injection Pump Drive | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Electrical Parts (Forwerded Individually Parts)
| YM***00 | Relay Ass'Y,Safety | 1 |
| YM***10 | Relay Ass'Y,Magnetic | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Engine Stop Motor
| YM***20 | Bracket | 1 |
| YM***80 | Ring,Snap | 1 |
| YM***30 | Spring | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Exhaust Manifold
| YM***02 | Nut | 2 |
| YM***02 | Stud | 2 |
| YM***02 | Screw | 6 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Flywheel And Flywheel Housing (For D20-7)
| YM***52 | Screw | 9 |
| YM***30 | Screw | 6 |
| YM***44 | Bearing | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Flywheel And Flywheel Housing (For D21-7)
| YM***52 | Screw | 9 |
| YM***90 | Flywheel Ass'Y | 1 |
| YM***30 | Screw | 6 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Front Cover And Oil Pump
| YM***02 | Bolt Plated | 3 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***02 | Screw | 10 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Front Hanger(#00101-00237)
| YM***00 | Suspension Plate | 1 |
| YM***62 | Bolt,(For Shipping) | 2 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Front Hanger(#00238-)
| YM***10 | Hook,Front | 1 |
| YM***62 | Bolt,(For Shipping) | 2 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Filter (Poor Fuel Type? Sandy And Dusty Spec.) (Inner Parts)
| YM***20 | Level Sensor Ass'Y | 1 |
| YM***30 | Plug,Drain | 1 |
| YM***00 | Fuel Filter Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Filter And Piping (Poor Fuel Type)(#02611-)
| YM***11 | Hose Ass'Y | 1 |
| YM***90 | Retainer | 1 |
| YM***70 | Joint | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Filter And Piping (Poor Fuel Type? Sandy And Dusty Spec.)(#00101-02610)
| YM***10 | Banjo Fitting | 1 |
| YM***90 | Retainer | 1 |
| YM***70 | Joint | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Filter And Piping(#00101-02610)
| YM***02 | Screw | 1 |
| YM***10 | Banjo Fitting | 1 |
| YM***80 | Screw | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Filter And Piping(#02611-)
| YM***02 | Screw | 1 |
| YM***80 | Screw | 1 |
| YM***11 | Hose Ass'Y | 2 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Feed Pump) (Inner Parts)
| YM***40 | Gasket | 4 |
| YM***60 | O-Ring | 2 |
| YM***10 | Feed Pump Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Feed Pump) (Inner Parts) (D21 Aircon? Trimming? Cold Terrain? Poor Fuel)(#02611-)
| YM***40 | Gasket | 4 |
| YM***60 | O-Ring | 2 |
| YM***10 | Feed Pump Ass'Y | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)
| YM***00 | Screw | 1 |
| YM***10 | Screw | 6 |
| YM***20 | Limiter | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts) (D21 Aircon? Trimming? Cold Terrain? Poor Fuel)(#02611-)
| YM***00 | Screw | 1 |
| YM***10 | Screw | 6 |
| YM***20 | Limiter | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)
| YM***40 | Screw | 2 |
| YM***00 | Nut | 1 |
| YM***40 | Shim, 0.300 mm | 0 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts) (D21 Aircon? Trimming? Cold Terrain? Poor Fuel)(#02611-)
| YM***40 | Screw | 2 |
| YM***00 | Nut | 1 |
| YM***40 | Shim, 0.300 mm | 0 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)
| YM***40 | Gasket | 2 |
| YM***00 | Adapter | 2 |
| YM***40 | Gasket | 2 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts) (D21 Aircon? Trimming? Cold Terrain? Poor Fuel)(#02611-)
| YM***40 | Gasket | 2 |
| YM***00 | Adapter | 2 |
| YM***40 | Gasket | 2 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)
| YM***00 | Segment | 4 |
| YM***00 | Gasket Disc | 4 |
| YM***20 | Valve,Delivery | 4 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts) (D21 Aircon? Trimming? Cold Terrain? Poor Fuel)(#02611-)
| YM***00 | Segment | 4 |
| YM***00 | Gasket Disc | 4 |
| YM***20 | Valve,Delivery | 4 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump And Piping
| YM***02 | Bolt Plated | 1 |
| YM***40 | Injection Pipe N. 4 | 1 |
| YM***20 | Retainer, Pipe | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Injection Pump And Piping (For D21 Air Conditioner? Trimmingdozer? Cold Terrain? Poor Fuel)(#02611-)
| YM***02 | Bolt Plated | 1 |
| YM***20 | Retainer, Pipe | 1 |
| YM***42 | Screw | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Fuel Nozzle And Spill Hose
| YM***20 | Spring | 1 |
| YM***00 | Fuel Injection Nozzle, Assembly | 1 |
| YM***80 | Pipe | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Gasket Kit(#00101-02610)
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***40 | O-Ring,Drain Plug | 1 |
| YM***01 | Gasket (Kit) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Gasket Kit(#02611-)
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***40 | O-Ring,Drain Plug | 1 |
| YM***01 | Gasket (Kit) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Head Cover
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***42 | Screw | 1 |
| YM***00 | Screw | 2 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Lubricating Oil Piping
| YM***81 | Retainer | 1 |
| YM***50 | Tube | 1 |
| YM***50 | Pipe | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Muffler
| YM***62 | Bolt | 1 |
| YM***02 | Nut | 4 |
| YM***22 | Stud | 4 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Oil Filter
| YM***40 | Stud | 1 |
| YM***51 | Cartridge,Cylinder Head Cover | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Oil Pan
| YM***00 | O-Ring (Kit) | 1 |
| YM***00 | Spacer | 1 |
| YM***40 | Plug,Drain | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Oil Pan (Cold Terrain Spec. And Poor Fuel Type)
| YM***00 | O-Ring (Kit) | 1 |
| YM***00 | Spacer | 1 |
| YM***40 | Plug,Drain | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Oil Pan (For Trimming Dozer And Poor Fuel Type)
| YM***00 | O-Ring (Kit) | 1 |
| YM***30 | Oil Pan Ass'Y | 1 |
| YM***00 | Spacer | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Oil Pan (For Trimming Dozer? Cold Terrain Spec. And Poor Fuel Type)
| YM***00 | O-Ring (Kit) | 1 |
| YM***00 | Spacer | 1 |
| YM***40 | Plug,Drain | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Piston And Connecting Rod
| YM***00 | Connecting Rod, Assembly | 4 |
| YM***01 | Pin, Piston | 4 |
| YM***10 | Bush,Idle Gear (Repair Part) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Rear Hange
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Rocker Arm
| YM***20 | Rocker Socket | 1 |
| YM***80 | Spring | 3 |
| YM***60 | Rocker Arm Ass'Y,Exhaust | 4 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Starting Motor (2.3kw) (Inner Parts)
| YM***20 | O-Ring | 1 |
| YM***22 | Starting Motor Ass'Y,(2.3kw) | 1 |
| YM***80 | Holder Brush, Assembly | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Starting Motor And Mounting (2.3kw)
| YM***02 | Nut | 1 |
| YM***02 | Screw | 1 |
| (Y***2) | Starting Motor Ass'Y,(2.3kw) (See Fig.A6210-B0a3) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Tool(#02611-)
| YM***40 | Horn,Flex | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Water Pump And Cooling Fan (For Trimming Dozer)(#02611-)
| YM***10 | Pulley | 1 |
| YM***52 | Bolt | 4 |
| YM***02 | Screw | 3 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Water Pump And Cooling Fan (For Trimming Dozer? Sandy And Dusty Spec.)(#00101-02610)
| YM***10 | Pulley | 1 |
| YM***90 | Thermostat | 1 |
| YM***02 | Screw | 3 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Water Pump And Cooling Fan (With Air Conditioner)(#00101-02610)
| YM***90 | Thermostat | 1 |
| YM***02 | Screw | 3 |
| YM***40 | Gasket (Kit) | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Water Pump And Cooling Fan (With Air Conditioner)(#02611-)
| YM***52 | Bolt | 4 |
| YM***02 | Screw | 3 |
| YM***00 | Fan,Cooling | 1 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Water Pump And Cooling Fan(#00101-02610)
| YM***90 | Thermostat | 1 |
| YM***50 | Pulley | 1 |
| YM***02 | Screw | 3 |
Komatsu : 4d94e-1a(S/N 00101-Up) : Engine : Water Pump And Cooling Fan(#02611-)
| YM***50 | Pulley | 1 |
| YM***60 | Thermostat Case A | 1 |
| YM***02 | Screw | 3 |
4D94E-1A(S/N 00101-UP) serial number reference
The 4D94E-1A engine's own ID plate sits on the engine block (left side, near the fuel injection pump) and reads the engine model plus a straight numeric serial, with this parts range starting at 00101-UP. The host machine's separate PIN/serial plate is on the machine frame - front frame rail on dozers and wheel loaders, near the mast/cowl on forklifts - and also runs as a plain numeric block (e.g. HA940051-UP, 75001-78603) rather than a Cat-style 3-letter alpha prefix, so match engine model and host serial block together in the parts book rather than decoding a letter code.
| Prefix | Identifies | Notes |
|---|---|---|
| 00101-UP | 4D94E-1A engine, base serial block (engine's own ID plate) | Engine's own stamped serial range for this naturally aspirated 4-cylinder industrial diesel (94mm bore), covered together with sibling 4D94E, 4D94E-1AB, 4D94E-1AH, 4D98E-family variants in the same Komatsu diesel engine shop manual. Distinct from any host machine PIN. |
| HA940051-UP | WA65-3 wheel loader host chassis, 4D94E-1A engine fitted | Serial break for the WA65-3 wheel loader in the factory shop manual scope covering the WA65/75/85/90/95-3 family. WA65-3's own factory spec sheet lists a 94/100mm bore/stroke 4-cylinder diesel at roughly 37kW, matching the 4D94E displacement class, and the 4D94E-1A engine fitment for WA65-3 (and WA65PT-3) is repeated across independent parts listings. |
| 75001-78603 | D21A-7(JPN) Trimming Dozer for C.I.S., 4D94E-1A engine fitted | Narrower serial break than the full dozer production run. Factory documentation splits this D21A-7 CIS trimming-dozer batch at S/N 78604, where the engine changes to a different 4D94E-1 emission-spec variant (not the 1A suffix covered here). Treat 75001-78603 as the 4D94E-1A-specific window; confirm exact unit against the engine plate. |
| 500001-UP | FD20-14 / FD25-14 / FD30-14 / FD30T-14 forklift host chassis, 4D94E-1A engine fitted | Reported serial start for the FD20/25/30-14 forklift truck series carrying the 4D94E-1A engine, repeated across separate manual listings. Confirm with dealer before ordering parts against this break. |
Frequently asked questions
What are the engine specifications for the Komatsu 4D94E-1A (S/N 00101-UP)?
It is a 4-cylinder, water-cooled, naturally aspirated diesel of roughly 2.8 liters (169 cu in) displacement, with a 94 mm bore and 100 mm stroke. Governed output is reported from about 29.5 kW (40 hp) up to roughly 43 kW (58 hp) depending on the host machine's governor setting, so check your specific application before ordering parts.
What is the operating weight of the Komatsu 4D94E-1A engine?
The bare engine weighs approximately 220-230 kg (485-505 lb) dry, before flywheel housing, starter, alternator, and other accessories are fitted. This is the engine's own weight, not the operating weight of the forklift, loader, or dozer it powers.
What replaced the Komatsu 4D94E-1A engine?
Komatsu moved this platform to the low-emission 4D94LE and later 4D94LE-2 variants, built to meet EPA Tier 2 requirements, while continuing to use them across the same FD20-30 forklift and D20/D21 dozer and loader families.
What 4D94E-1A(S/N 00101-UP) owners discuss
What's the general reputation of the 4D94E-1A engine among owners running it in forklifts and small excavators/loaders?
Owners describe it as a durable, naturally aspirated direct-injection four-cylinder that holds up well under normal duty cycles. Some report a modest power drop when working continuously at full load or in high ambient heat, which is typical for this displacement class rather than a specific defect. On higher-hour units, wiring and connector corrosion on the engine harness comes up more often than internal engine failures.
Owners doing their own injection pump timing on this engine mention alignment marks that are easy to miss. What's the trick?
The injection pump timing reference is a small chisel or punch mark on the top outer pump mounting bolt, matched to a corresponding mark on the front timing cover. Align those two marks and the pump is in time. The marks are easy to overlook after a pump removal and reinstall, so confirm alignment with a dial indicator or timing light before restarting the engine. Because incorrect timing can cause hard starting, knock, or engine damage, have your dealer verify final timing.
White smoke and a hard cold start. Is that a glow plug problem on this engine?
That's the first thing techs check. A failed glow plug, or a fault in the glow-plug relay/timer circuit, commonly shows up as hard starting, rough idle, and white smoke at cold start. Testing each plug's resistance with a multimeter isolates a bad one quickly; a healthy plug reads low single-digit ohms, while an open or infinite reading means it has failed. If all plugs test good, check compression and fuel quality next, since low compression produces the same white-smoke symptom.
What driveline wear pattern shows up on 4D94E-1A forklifts as hours climb?
On units built with the dry-clutch/torque-converter driveline, clutch plate glazing and thinning is the most commonly reported wear item, along with occasional internal seal or turbine wear in the torque converter that causes weak pushing power even though the engine revs normally. Grinding or whining noise from the transmission area, or a complaint of weak drive with normal RPM, points to the clutch pack or converter rather than the engine itself. This is a driveline teardown job, so have your dealer verify before condemning parts.
Any wear patterns to watch on the mast and chain side of these forklifts?
Independent of the engine, mast chain elongation and turned pins are the most common failure mode reported on these trucks, usually traced back to skipped lubrication rather than a design flaw. A chain stretched beyond roughly three percent of its original length is due for replacement, and turned or rusted pins signal it has gone too long between services. Owners are advised to pair daily visual checks with a professional chain inspection annually or every 1,000 hours, since a failed mast chain is a load-drop hazard, not just a maintenance item.
What typically causes overheating complaints on this engine?
Reported causes, roughly in order of frequency, are a partially clogged radiator restricting airflow, a fan belt that has gone loose or glazed, a weakening thermostat, and a water pump starting to leak or seize. Coolant loss with no visible external puddle often traces back to a failing water pump seal on higher-hour units. Work through radiator, belt, thermostat, and pump before assuming a head gasket problem.
What should I check before buying a used machine carrying a 4D94E-1A(S/N 00101-UP) engine?
Confirm which driveline the unit carries, since a dry-clutch/torque-converter forklift and a wheeled or tracked host have different wear points to check. Pull an oil sample and run a cylinder compression test to flag ring or valve wear before you commit. Check for coolant weeping at the water pump, inspect mast chains for elongation and turned pins if it's a forklift, and confirm the glow plugs and starter bring the engine to life without hesitation from cold. Ask for maintenance records; owners report oil and filter changes on roughly a 250-hour cycle as the norm, and gaps in that history are a red flag. Have your dealer verify compression readings and driveline condition against factory specs before final purchase.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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