Komatsu 4D84-2GA(S/N 04595-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 4D84-2GA engine (S/N 04595-UP) is a compact, inline four diesel powerplant designed for mini excavators and small wheel loaders. It typically powers machines in the 10 to 20 metric ton operating weight class, such as the PC40-7, PC45-1, and PC50UU-2 series. Production for this specific serial range spans the mid-2000s to early 2010s, bridging the gap between the earlier 4D84-2A and the later 4D84-2B variants. The engine is characterized by its vertical layout, 2.0-liter displacement, and compliance with Tier 2/Stage II emissions standards, offering a balance of torque and fuel efficiency for tight job site applications.
Across the 4D84 series generations, primary changes involved emissions compliance upgrades and minor internal component revisions to meet stricter global standards. The 4D84-2GA variant specifically addresses the transition period where fuel injection timing and turbocharger mapping were refined to improve low-end torque without increasing exhaust temperatures. In the used and parts market, this engine remains critical because it powers a high volume of entry-level excavators still in active service. Its compact design allows for easy access to undercarriage and hydraulic components, making it a staple for fleet managers prioritizing uptime and low-cost maintenance over raw power output.
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 4D84-2GA(S/N 04595-UP) specifications
Engine
| Model | 4D84-2GA |
| Series | 4D84 |
| Displacement | 1,995 cm³ (121.7 cu in) |
| Cylinders | 4 |
| Layout | Inline |
| Power | 30.1 hp (22.4 kW) @ 3,000 rpm |
| Emissions Tier | Not documented for this exact serial range — verify with your dealer |
Weights
| Operating weight | Not documented for this exact serial range — verify with your dealer |
| Shipping weight | Not documented for this exact serial range — verify with your dealer |
| Ground pressure | Not documented for this exact serial range — verify with your dealer |
Dimensions
| Transport length | Not documented for this exact serial range — verify with your dealer |
| Transport width | Not documented for this exact serial range — verify with your dealer |
| Transport height | Not documented for this exact serial range — verify with your dealer |
| Track gauge | Not documented for this exact serial range — verify with your dealer |
| Ground clearance | Not documented for this exact serial range — verify with your dealer |
Performance
| Travel speed | Not documented for this exact serial range — verify with your dealer |
| Gradeability | Not documented for this exact serial range — verify with your dealer |
Service capacities (summary)
| Engine oil | Not documented for this exact serial range — verify with your dealer |
| Hydraulic system | Not documented for this exact serial range — verify with your dealer |
| Cooling system | Not documented for this exact serial range — verify with your dealer |
| Fuel tank | 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 4D84-2GA(S/N 04595-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 4D84-2GA(S/N 04595-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize KOWA fluid analysis at every 500-hour interval to monitor wear metals and contamination. Check coolant SCA concentration at 500 hours to prevent cavitation in the 4D84-2GA cylinder liners. Monitor hydraulic oil particle count to protect the main control valve in PC40-7 and PC50UU-2 models. Track engine oil viscosity and fuel dilution to detect piston ring wear early. Use KOMTRAX telematics to correlate high load frequency with accelerated fluid degradation. Adjust service intervals based on site dust levels and ambient temperature extremes.
Corrective & Common Repairs
Address frequent failures in the 4D84-2GA by inspecting the fuel injector nozzles for clogging, which causes black smoke and power loss. Replace worn turbocharger shafts if excessive shaft play is detected during the 1,000-hour inspection. Check the water pump impeller for erosion if coolant flow drops. Inspect the alternator brushes and voltage regulator for charging issues common in older units. Replace cracked hydraulic hoses at the boom base where flexing is highest. Verify the integrity of the engine mount bolts to reduce vibration-induced fatigue.
Overhaul & Rebuild Points
Plan for a major engine overhaul when compression drops below specification or blue smoke indicates excessive oil consumption. Replace cylinder liners and pistons if scoring is visible during disassembly. Inspect the crankshaft main and rod bearings for wear; replace if clearance exceeds limits. Check the camshaft lobes for pitting or flattening. Recondition the cylinder head by resurfacing the gasket face and replacing valve guides and seats. Ensure all gaskets and seals are replaced with a complete overhaul kit to prevent leaks.
Seasonal & Environment Servicing
In cold climates, use low-viscosity engine oil and ensure the coolant mixture provides adequate freeze protection. Preheat the engine using a block heater before starting in temperatures below -10°C. In dusty environments, check the air filter restriction indicator daily and clean the outer element more frequently. In high-humidity areas, drain the fuel water separator more often to prevent microbial growth. Inspect the radiator and oil cooler fins for debris buildup to maintain optimal heat exchange. Verify the battery holds charge in extreme cold.
4D84-2GA(S/N 04595-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| YM129100-55650 | Element,Fuel Filter | Fuel system service | Check fitment → |
| YM129100-55621 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| YM102103-55520 | O-Ring,(For Fuel Filter) | Fuel system service | Check fitment → |
| YM129436-12900 | Element,Outer | Scheduled service item | Check fitment → |
| YM129436-12910 | 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.
4D84-2GA(S/N 04595-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor failure | Broken sensor, wiring issue, or connector corrosion | Replace the speed sensor and verify the voltage at the pin connector |
| CA451 | Common rail pressure sensor feedback value too high | Malfunction in the rail sensor or actual overpressure condition | Diagnose the fuel rail pressure sensor or pump lines |
| CA122 | Intake air pressure high voltage | Faulty intake pressure sensor or wiring | Verify the intake pressure sensor and wiring |
| CA123 | Intake air pressure low voltage | Sensor short or airflow restriction | Check for a sensor short or an airflow restriction |
| CA441 | Battery voltage too low | Alternator or battery failure; voltage regulator issue | Replace the alternator or battery; check the voltage regulator |
| AA10NX | Air cleaner clogging | Dirty or blocked air filter element | Replace the air filter |
| CA153 | Intake air temperature sensor feedback voltage too high | Faulty intake air temperature (IAT) sensor | Replace or test the IAT sensor |
| CA428 | Fuel moisture sensor invalid voltage | Contaminated fuel supply or sensor harness issue | Ensure a clean fuel supply and check the moisture sensor harness |
| CA234 | Engine overspeed | Throttle calibration error, engine load cycle issue, or operator misuse | Verify throttle calibration, engine load cycle, or operator misuse |
| CA111 | Internal engine controller fault | ECM internal failure | Replace or reprogram the ECM |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
4D84-2GA(S/N 04595-UP) attachments & work tools
Excavator Buckets
Standard and heavy-duty digging buckets are the primary work tool for the PC40-7, PC45-1, and PC50UU-2 mini excavators powered by this engine. Typical capacities for this class range from 0.02 to 0.04 cubic meters (0.03 to 0.05 cubic yards), varying by configuration/series based on the specific machine model and ground conditions.
Trenching Buckets
Narrow-width trenching buckets are offered for utility and pipeline work in the same machine class. Widths typically range from 300 to 600 millimeters (12 to 24 inches), with capacities scaled to maintain the machine's rated operating weight and hydraulic flow limits.
Quick Couplers
Hydraulic quick couplers are available for rapid tool changes on these mini excavators. Mounting systems are specific to the stick and bucket pin diameters of the PC40-7, PC45-1, or PC50UU-2 models, requiring compatible hydraulic lines from the main control valve.
Hydraulic Breakers
Mini hydraulic breakers are compatible with this engine class, utilizing the machine's auxiliary hydraulic circuit. Flow and pressure requirements vary by configuration/series; the breaker must match the PC40-7/PC45-1/PC50UU-2 auxiliary pump output to function correctly without damaging the engine or hydraulic system.
Augers
Post-hole augers are used for drilling applications on these compact machines. Drive systems typically connect to the auxiliary hydraulic outlet, with hole diameters ranging from 300 to 600 millimeters (12 to 24 inches) depending on the auger flighting size and machine stability.
Grapples and Clamps
Material handling grapples and brush clamps are available for recycling and landscaping tasks. These tools require a dedicated hydraulic circuit for opening and closing, often utilizing a flow divider or separate pump circuit if the machine is equipped with the necessary factory options.
Factory Guarding Options
Factory-installed guarding options include FOPS (Falling Object Protective Structure) and ROPS (Rollover Protective Structure) cabs or canopies. These structures are integrated into the machine's frame and certified to meet specific safety standards for the operating environment.
All 4D84-2GA(S/N 04595-UP) assemblies by section
Every catalogued assembly group for the Komatsu 4D84-2GA(S/N 04595-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Accessory
Komatsu : 4d84-2ga(S/N 04595-Up) : Accessory : P. P. C. Pump And Mounting
| YM***20 | Pump Ass'Y,Hydraulic | 1 |
| YM***81 | Gasket (Kit) | 1 |
| YM***50 | Bracket | 1 |
Cooling System
Komatsu : 4d84-2ga(S/N 04595-Up) : Cooling System : Water Pump And Cooling Fan
| YM***20 | Gasket,Water Pump | 1 |
| YM***02 | Screw | 4 |
| YM***02 | Screw | 1 |
Cylinder Block
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Camshaft And Tappet
| YM***80 | Camshaft Ass'Y | 1 |
| YM***01 | Gear Ass'Y,Camshaft | 1 |
| YM***50 | Bearing, Thrust | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Crankshaft
| YM***00 | Gear,Crank | 1 |
| YM***80 | Parallel Pin | 1 |
| YM***50 | Pulley,Crank | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Cylinder Block
| YM***00 | O-Ring (Kit) | 1 |
| YM***20 | Plug,Drain(Without Oil Cooler Type) | 1 |
| YM***20 | Screw | 10 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Flywheel And Flywheel Housing
| YM***90 | Flywheel Ass'Y | 1 |
| YM***80 | Parallel Pin | 4 |
| YM***02 | Bolt | 6 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Front Cover And Gear
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***90 | Front Cover Ass'Y | 1 |
| YM***10 | Washer,Seal | 9 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Oil Pan
| YM***30 | Spacer | 1 |
| YM***02 | Screw | 4 |
| YM***40 | O-Ring,Drain Plug | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Block : Piston And Connecting Rod
| YM***20 | Piston Ass'Y | 4 |
| YM***00 | Screw | 2 |
| YM***00 | Crank Pin Metal A. (Std) | 1 |
Cylinder Head
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Air Cleaner And Mounting (Double Element Type)
| YM***41 | Buffle | 1 |
| YM***10 | Cap | 1 |
| YM***30 | Pan,Dust | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Air Cleaner And Mounting (Single Element Type)
| YM***41 | Buffle | 1 |
| YM***10 | Cap | 1 |
| YM***30 | Pan,Dust | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Air Intake Manifold And Connection
| YM***01 | Heater,Intake Air | 1 |
| YM***00 | Clamp | 2 |
| YM***00 | Manifold,Air Intake | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Cylinder Head
| YM***80 | Retainer, Spring | 8 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***10 | Valve,Exhaust | 4 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Cylinder Head Cover
| YM***20 | Cover, Breather | 1 |
| YM***51 | Cap, Lub. Oil Supply | 1 |
| YM***90 | Retainer | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Exhaust Manifold And Muffler
| YM***22 | Stud | 4 |
| YM***01 | Gasket (Kit) | 1 |
| YM***10 | Gasket (Kit) | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Cylinder Head : Rocker Arm
| YM***02 | Nut,Rock | 3 |
| YM***02 | Screw | 7 |
| YM***80 | Spring | 4 |
Electrical System
Komatsu : 4d84-2ga(S/N 04595-Up) : Electrical System : Alternator (40a)
| YM***50 | Brush Ass'Y | 1 |
| YM***00 | Retainer,Bearing | 1 |
| YM***70 | Diode Ass'Y | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Electrical System : Alternator And Mounting (40a)
| YM***30 | Plate,Adjust | 1 |
| YM***02 | Nut | 1 |
| YM***02 | Nut | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Electrical System : Safety Relay
| YM***00 | Relay, Safety | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Electrical System : Starting Motor (2kw)
| YM***50 | Pinion Ass'Y,Pinion | 1 |
| YM***20 | Housing,Center | 1 |
| YM***40 | Field Coil Ass'Y | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Electrical System : Starting Motor And Mounting (2kw)
| YM***52 | Bolt Plated | 2 |
| YM***02 | Nut,Rock | 1 |
| YM***00 | Washer,Spring | 1 |
Fuel System
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Engine Stop Motor And Mounting
| YM***80 | Ring,Snap | 1 |
| YM***00 | Pin,Cotter | 1 |
| YM***20 | Bracket | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Filter And Piping
| YM***70 | Union | 1 |
| YM***02 | Bolt | 1 |
| YM***00 | O-Ring (Kit) | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2)
| YM***02 | Lever Ass'Y,Stop | 1 |
| YM***10 | Pin,Stop Lever | 1 |
| YM***00 | O-Ring (Kit) | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2)
| YM***01 | Weight Assembly., Governor | 1 |
| YM***90 | Shaft,Governor Lever | 1 |
| YM***50 | Angleich Ass'Y | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Injection Pump (Pump) (1/2)
| YM***50 | Kit, Shim | 1 |
| YM***10 | Plate? Caution | 1 |
| YM***90 | Key,Woodruff | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Injection Pump (Pump) (2/2)
| YM***70 | Retainer, Spring | 4 |
| YM***00 | Plunger Ass'Y | 4 |
| YM***00 | Rack,Control | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Injection Pump And Piping
| YM***30 | Bolt | 2 |
| YM***20 | Retainer, Pipe | 1 |
| YM***02 | Nut | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Fuel Nozzle And Spill Pipe
| YM***20 | Spring | 1 |
| YM***00 | Fuel Injection Nozzle, Assembly | 1 |
| YM***80 | Seat,Nozzle (Kit) | 4 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Fuel System : Water Separator And Piping
| YM***10 | Hose,(See Fig.0415-17?0416-17) | 1 |
| YM***00 | Gasket | 2 |
| YM***00 | O-Ring (Kit) | 1 |
Lubricating Oil System
Komatsu : 4d84-2ga(S/N 04595-Up) : Lubricating Oil System : Lubricating Oil Filter And Mounting
| YM***50 | Nut | 1 |
| YM***02 | Bolt Plated | 3 |
| YM***00 | Valve,Relief | 1 |
Komatsu : 4d84-2ga(S/N 04595-Up) : Lubricating Oil System : Lubricating Oil Pump And Piping
| YM***10 | Washer,Seal | 2 |
| YM***50 | Oil Pressure Transmitter | 1 |
| YM***50 | Pipe,Oil | 1 |
Tool And Kit
Komatsu : 4d84-2ga(S/N 04595-Up) : Tool And Kit : Gasket Kit
| YM***60 | O-Ring,Fuel Injection Pump | 1 |
| YM***40 | Seal,Valve? Exhaust (Kit) | 4 |
| YM***20 | Gasket,Water Pump | 1 |
4D84-2GA(S/N 04595-UP) serial number reference
The engine serial number plate is located on the left side of the engine block, typically near the injection pump or on a metal data plate affixed to the engine block or valve cover. The prefix is part of the engine model code stamped on this plate, not a separate 3-character PIN prefix; the engine model code (e.g., 4D84-2GA) identifies the engine family and configuration for this serial range.
| Prefix | Identifies | Notes |
|---|---|---|
| 4D84-2GA | Engine Model | Komatsu 4D84-2GA engine. Serial range 04595-UP. Source: published references catalog listing for 4D84-2GA S/N 04595-UP. No specific 3-character PIN prefixes found in source text for this engine range; PINs are machine-level identifiers, not engine-level. The engine model code itself (4D84-2GA) serves as the primary identifier in parts catalogs for this serial range. Source: published references catalog listing for 4D84-2GA S/N 04595-UP. |
Frequently asked questions
What engine does the Komatsu 4D84-2GA (S/N 04595-UP) use?
It uses the Komatsu 4D84-2GA inline-four, 2.0-liter diesel engine, typically found in PC40-7, PC45-1, and PC50UU-2 excavators.
What is the operating weight of machines powered by this engine?
Machines equipped with this engine, such as the PC40-7 and PC50UU-2, typically have an operating weight ranging from 4,000 to 5,500 kg (8,800 to 12,100 lb), depending on the configuration and attachment.
What replaced the Komatsu 4D84-2GA engine?
The 4D84-2GA was succeeded by the 4D84-2B and later Tier 3/Tier 4 compliant engines as emissions regulations tightened, though the 4D84 series lineage continues in various forms for compact equipment.
Need a specific 4D84-2GA(S/N 04595-UP) part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.