Komatsuengine(no series)

Komatsu 3D82E-3A(S/N 00101-UP)

Maintenance schedule, common problems & OEM parts breakdown

Search live 3D82E-3A(S/N 00101-UP) parts

The Komatsu 3D82E-3A is a bare industrial diesel engine, not a complete machine. It is a vertical, water-cooled, four-cycle, direct-injection three-cylinder diesel built on an 82 mm x 90 mm (3.23 x 3.54 in) bore and stroke for a displacement of 1.425 L (87 cu in), with an 18.0:1 compression ratio and no electronic engine controls; it is mechanically governed like other industrial diesels of its era. Family output for this bore and stroke runs roughly 15.5-23.2 kW (20.8-31.1 hp) across a governed-speed band of about 2,000-3,000 rpm, with the exact rating for the -3A calibration set by the host machine's injection-pump and governor tune rather than published on its own. Dry weight is 138 kg (304 lb) or 155 kg (342 lb) depending on the flywheel-housing option fitted. It belongs to Komatsu's 68E-88E small-diesel engine family, which spans 2-cylinder through 4-cylinder blocks sharing common architecture, and Komatsu fitted this -3A calibration (S/N 00101-UP) as original power in compact excavators including the PC15-3, PC20-7, PC25-1, and PC30-7.

A closely related sibling in the same shop manual, the 3D82AE, uses a shorter 84 mm stroke and a different displacement; the two get blended under a shared "82-series" label in casual references but should not be confused when sourcing parts or reading specs. Within its own "-3" generation the 3D82E was carried forward through further lettered updates before Komatsu moved this bore size onto the "-5" generation and eventually the 82E-6/98E-6 series as fuel-injection and accessory-drive detail advanced, and none of the host machines above stayed on the -3A calibration for their whole production run. Because it predates electronic engine management, the 3D82E-3A stays mechanically simple and field-serviceable, which keeps it in demand today as a rebuildable core or parts donor for older Komatsu mini excavators still working in the field. Exact-generation replacement blocks are increasingly scarce, so buyers commonly cross-shop later-generation family engines as functional replacements when a -3A core is not economical to rebuild.

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 3D82E-3A(S/N 00101-UP) specifications

Engine

Engine family	Komatsu 3D82E-3A (S/N 00101-UP), a calibration variant within the 3D82E engine family (Komatsu 68E-88E series industrial/construction diesel line)
Type	Vertical, 4-cycle, water-cooled diesel; direct injection
Cylinders	3, inline
Bore x stroke	82 x 90 mm (3.23 x 3.54 in)
Displacement	1.425 L (87 cu in)
Compression ratio	18.0:1
Max rated output (family range)	15.5-23.2 kW (20.8-31.1 hp) across a governed-speed range of roughly 2,000-3,000 rpm; exact rating for this -3A calibration is set by the host machine's governor/injection-pump setup and is not separately published
Firing order	1-3-2
Rotation	Counterclockwise, viewed from flywheel
Emissions tier	Not documented for this engine. It is a mechanically governed diesel with no electronic emissions controls, consistent with pre-Tier industrial engines of this design era

Weights

Dry weight	138 kg (304 lb) or 155 kg (342 lb), depending on flywheel-housing configuration
Ground pressure	Not applicable - bare engine, not a complete machine

Dimensions

Overall length x width x height

556 x 486 x 623 mm (21.9 x 19.1 x 24.5 in), or 564 x 486 x 623 mm (22.2 x 19.1 x 24.5 in) depending on flywheel-housing configuration

Performance

Minimum no-load (idle) speed	800 rpm or higher
Compression pressure	3.04 +/- 0.1 MPa (31 +/- 1 kgf/cm2) at 250 rpm cranking speed
Fuel injection pressure	19.6 MPa (200 kgf/cm2)
Fuel injection timing	12 to 16 degrees +/- 1 degree BTDC, depending on configuration

Service capacities (summary)

Cooling water capacity	2.0 L (0.53 US gal), engine only
Lubricating oil capacity	About 1.8-2.1 L (0.48-0.55 US gal) between low and full marks, up to 4.7-6.9 L (1.24-1.82 US gal) total system capacity depending on configuration
Fuel tank	Not applicable - bare engine has no integral fuel tank; capacity is set by the host machine
Hydraulic system	Not applicable - engine has no integral hydraulic system; capacity is set by the host machine

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

3D82E-3A(S/N 00101-UP) fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase (with filter)	4.7-6.9 L (1.2-1.8 US gal) total refill, depending on oil pan/oil cooler configuration fitted; 1.8-2.1 L (0.5-0.6 US gal) between the low and full dipstick marks	API Service Classification CC or higher. Viscosity by ambient temperature: SAE 10W in cold conditions, SAE 20W or 20W-20 in temperate conditions, SAE 20W-30 or 20W-40 in hot conditions, or a multigrade SAE 10W-30 across a wide temperature swing (SAE 5W-20 for extreme cold below about -20C/-4F). Komatsu Genuine EO10W-30 or EO15W-40 diesel engine oil meets this spec.
Cooling system	2.0 L (0.53 US gal), engine block only. Actual system fill depends on the radiator and hoses fitted by the machine builder, not fixed by the engine alone.	Ethylene-glycol antifreeze/coolant mixed with soft, distilled, or demineralized water; never run on water alone. Change coolant every 400 hours or once a year, whichever comes first. Komatsu Genuine AF-NAC super coolant, an all-season corrosion-inhibited formula, meets this spec.
Fuel system	No integral fuel tank on the bare engine. Day tank size is set by the machine it is installed in and is not documented at the engine level.	Diesel fuel equal to or better than ISO 8217 DMA, or BS 2869 Part 1 Class A1 / Part 2 Class A2, minimum cetane number 45.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Komatsu 3D82E-3A(S/N 00101-UP) maintenance schedule

Service interval	Tasks
Every 50 h	Check engine oil level on the dipstick before starting and top up to the full mark with the correct seasonal-viscosity grade. Check coolant level in the radiator or reservoir fitted by the host machine; top up with a proper ethylene-glycol mix, never plain water. Drain water and sediment from the fuel strainer bowl; a clogged brass screen is the most common cause of hard starting or stalling under load on this engine. Check for fuel, oil, and coolant leaks around the block, fittings, and flywheel housing. Check fan and alternator belt tension and condition, and watch the charge lamp at start-up. Confirm the preheat/glow lamp cycles normally on cold starts and clears within the normal time before cranking.
Every 250 h	Change engine oil and filter using an API CC-or-better oil in the seasonal viscosity grade called for by ambient temperature. Clean or replace the fuel strainer element; clear the factory brass-mesh screen by reverse-blowing air if fitted. Inspect and re-torque the flywheel-housing mounting bolts that connect the engine to the driven pump or alternator. Check glow-plug resistance and preheat relay wiring for corrosion or a bad ground. Inspect radiator hoses, clamps, and the fan belt for cracking or glazing.
Every 500 h	Change coolant with a fresh ethylene-glycol antifreeze and soft-water mix (factory guidance calls for a change around every 400 hours or once a year, whichever comes first). Check compression pressure on all three cylinders against factory spec and compare cylinder to cylinder. Inspect injection nozzles for spray pattern and carbon buildup; clean or recondition as needed. Check valve clearance and adjust if outside tolerance. Test the oil pressure and oil level switch/sender operation rather than trusting the panel lamp alone.
Every 1,000 h	Replace the air cleaner element regardless of visual condition. Have injection timing checked and reset to the factory window if it has drifted. Inspect the water pump shaft seal for weeping before it reaches the timing gear cover. Check that the thermostat opens at the correct temperature and replace if sticking. Inspect starter and alternator brush wear and wiring connections.
Every 2,000 h	Pull and bench-test all injectors for pop pressure and spray pattern; recalibrate or exchange the injection pump if delivery is uneven cylinder to cylinder. Check crankshaft pulley and damper condition. Re-torque cylinder head bolts to factory sequence and spec. Inspect main and connecting-rod bearing clearances where access allows without a full teardown. Verify flywheel-housing alignment to the driven-equipment coupling, and recheck after any major fuel-system work.
Every 4,000 h	At major overhaul, measure cylinder liner and piston-ring wear against factory limits before honing; this bore runs tight tolerances. Inspect valve seat recession and guide clearance on the direct-injection head. Rebuild or exchange the injection pump rather than reusing worn components on guesswork. Replace the water pump seal kit preventively rather than waiting for visible weeping. Confirm crankshaft and main bearing clearances are within factory limits before reassembly.

Servicing the 3D82E-3A(S/N 00101-UP) beyond the schedule

Predictive Maintenance & Fluid Analysis

Send crankcase oil for wear-metal analysis at every oil change; on this mechanically governed engine, rising iron or copper counts flag injection-pump plunger and delivery-valve wear well before power loss is felt at the flywheel coupling. Track coolant condition in the small 2.0 L engine-only water jacket for corrosion-inhibitor depletion, a driver of water pump and liner pitting on this family. Log preheat cycle time and glow-plug resistance over successive cold starts, and sample fuel from the strainer bowl to catch contamination before it damages the injection pump.

Corrective & Common Repairs

Cold no-start or a weak preheat cycle traces to the glow-plug relay, its wiring or ground, and individual glow-plug resistance, not the injection pump; test the electrical side first. Cranks-but-won't-fire or dying under load usually comes from a clogged fuel strainer screen, cleared by reverse-blowing air, or air pulled in at a loose fitting, well before the injectors are at fault. Oil pressure, water temperature, and charge lamps each point to a specific check: oil level and pump, coolant level and thermostat, or belt tension and alternator output.

Overhaul & Rebuild Points

At teardown, measure cylinder liner and piston-ring wear against factory limits before honing; this bore runs tight tolerances. Check compression on each cylinder against the factory figure as a go/no-go gate, inspect valve seat recession and guide clearance on the direct-injection head, and recalibrate or exchange the injection pump rather than reusing it on guesswork. Verify flywheel-housing alignment and bolt torque to the driven pump or alternator coupling before final reassembly, since this bare engine bolts straight to external equipment with no chassis to absorb misalignment.

Seasonal & Environment Servicing

In cold climates, confirm glow-plug and relay function plus battery condition before winter; this small naturally aspirated diesel depends on a clean preheat cycle for reliable cold starts. Check antifreeze concentration in the compact water jacket, since it holds little coolant and has less margin than a larger block, and switch to a winter-grade diesel to protect the mechanical injection pump. In hot or dusty duty, shorten air-cleaner service intervals, keep the radiator or heat-exchanger core clear of packed debris, and match oil viscosity to the seasonal temperature chart.

3D82E-3A(S/N 00101-UP) common service parts

Part number	Part	Notes
YM119833-55620	Fuel Filter Ass'Y	Fuel system service	Check fitment →
YM102103-55520	O-Ring,(For Fuel Filter)	Fuel system service	Check fitment →
YM171051-92760	Wrench,Fuel Filter? Water Separator	Fuel system service	Check fitment →
YM119810-35300	Intake Oil Filter	Lubrication service	Check fitment →
YM119640-92750	Wrench,Oil Filter? (Pc38uu)	Lubrication service	Check fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

3D82E-3A(S/N 00101-UP) fault codes & troubleshooting

Code	Meaning	Likely cause	What to do
Preheating (Glow Plug) Pilot Lamp	Amber coil-symbol lamp on the monitor panel shows the glow plugs are energized during the cold-start preheat cycle.	Lamp that stays on too long, flickers, or never lights points to a weak or open glow-plug element, a bad preheat relay/timer, or a wiring fault.	Time the preheat cycle against the factory spec; if abnormal, check glow-plug resistance and the preheat relay before replacing components.
Engine Oil Pressure Caution Lamp	Red oil-can symbol lights when engine oil pressure drops below the safe minimum.	Low oil level, a clogged oil filter or strainer, a worn oil pump, or a failed pressure switch/sender.	Stop the engine immediately, check the oil level and top up with the correct grade; if level is correct, check the pressure switch and oil pump before restarting.
Engine Oil Level Caution Lamp	Separate lamp from the pressure lamp; warns that sump oil level itself is low, independent of running oil pressure.	Oil consumption, an external leak, or oil not topped off at the last service interval.	Check the dipstick with the engine off and the machine level; add oil to the correct mark.
Water Temperature Caution Lamp	Red thermometer symbol lights when coolant temperature exceeds the safe operating range.	Low coolant level, a clogged radiator core, a failed thermostat, or a slipping/broken fan belt.	Stop the engine, let it cool, check coolant level and belt tension, and inspect the radiator core for blockage before restarting.
Charge Caution Lamp	Red battery symbol lights when the alternator is not charging the battery.	A slipping or broken alternator belt, a faulty alternator, or a loose/corroded wiring connection.	Check belt tension and wiring connections, test alternator output, and replace the belt or alternator as needed.
Fuel Gauge / Low Fuel Indication	Panel fuel gauge (or low-fuel lamp on some configurations) shows remaining fuel in the tank.	A reading pegged at empty or erratic usually means the tank is near empty, or the sender unit/wiring has failed.	Refuel with the correct diesel grade; if the gauge is erratic with fuel present, check the sender unit and wiring.

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

3D82E-3A(S/N 00101-UP) attachments & work tools

Machine type / scope

3D82E-3A(S/N 00101-UP) is a component diesel engine from Komatsu's 68E-88E industrial engine family, not a complete machine. It carries no bucket, coupler, or ground-engaging work-tool line of its own; any attachment or work-tool compatibility belongs to the host equipment it powers, not to the engine catalog.

OEM host-equipment applications

This engine block powers small Komatsu compact equipment, most notably the PC15-3, PC20-7, PC25-1, and PC30-7 compact excavators, alongside general industrial and agricultural gear such as generator sets, water pumps, and compactors built around the 68E-88E series. Work-tool options for those roles (buckets, breakers, couplers) are set by the host machine builder's own attachment guide, not by the engine spec sheet.

Flywheel / driven-equipment coupling

As with other engines in this family, output is taken off a flywheel and flywheel housing sized to an SAE-pattern bellhousing, allowing direct or flexible-coupled drive to a hydraulic pump (excavator use), PTO clutch, or generator adapter. Exact SAE housing/flywheel size for the 3A tune is not published in available spec sheets for this serial range - verify against the OEM installation drawing or with a Komatsu industrial-engine dealer before sourcing a coupling.

Guarding / installation hardware

Industrial/OEM installation packages for this engine family commonly include a cooling shroud, drive-belt and fan guarding, and mounting feet or isolators for integration into a pump or compactor frame. No model-specific factory options list (special guarding kits, cold-weather kit, etc.) for the 3A variant specifically was found in dealer or parts-catalog literature - treat as varies by OEM installer/configuration.

Related variant note

3D82E-3B and the turbocharged 3D82AE line are distinct engines that share parts-cross-reference listings with this block but power different host machines, including the PC27R-8 excavator family. Do not assume shared specs, options, or applications with those engines beyond a common parts listing.

All 3D82E-3A(S/N 00101-UP) assemblies by section

Every catalogued assembly group for the Komatsu 3D82E-3A(S/N 00101-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Cooling System

Komatsu : 3d82e-3a(S/N 00101-Up) : Cooling System : Water Pump And Cooling Fan

YM***02	Bolt Plated	2
YM***02	Screw	4
YM***20	O-Ring,(Not Shown)	1
YM***40	Fan,Cooling	1

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Cylinder Block

Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Camshaft And Tappet

YM***01	Gear Ass'Y,Camshaft	1
YM***00	Rod,Push	6
YM***50	Bearing, Thrust	1
YM***62	Bolt,(For Shipping)	2

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Crankshaft

YM***00	Gear,Crank	1
YM***80	Parallel Pin	1
YM***50	Pulley,Crank	1
YM***10	Spring Pin	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Cylinder Block

YM***00	Gauge, Oil Level	1
YM***30	Thrust Metal Ass'Y (Std)	2
YM***20	Plug,Drain(Without Oil Cooler Type)	1
YM***00	Plug	2

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Flywheel And Flywheel Housing

YM***50	Oil Seal Case, Assembly	1
YM***80	Seal? Rear	1
YM***02	Screw	6
YM***02	Screw	4

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Front Cover

YM***02	Bolt Plated	2
YM***51	Cap, Lub. Oil Supply	1
YM***52	Bolt	4
YM***40	O-Ring,Drain Plug	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Oil Pan

YM***40	Plug,Drain	1
YM***52	Screw	22
YM***40	Plug,Drain	1
YM***80	O-Ring,Engine Oil Drain	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Block : Piston And Connecting Rod

YM***00	Connecting Rod, Assembly	3
YM***80	Piston, Assembly	3
YM***00	Screw	2
YM***50	Ring Set (+0.25 mm)	1

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Cylinder Head

Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Head : Air Cleaner And Mounting

YM***41	Buffle	1
YM***10	Support	1
YM***10	Cap	1
YM***30	Pan,Dust	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Head : Air Intake Manifold And Connection

YM***81	Pipe	1
YM***52	Screw	4
YM***00	Heater,Intake Air	1
YM***10	Gasket,Heater (Kit)	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Head : Cylinder Head

YM***80	Retainer, Spring	6
YM***00	Guide,Valve? Exhaust	6
YM***00	Plug	2
YM***00	Bolt,Head	14

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Head : Cylinder Head Cover

YM***20	Cover, Breather	1
YM***51	Cap, Lub. Oil Supply	1
YM***00	Clip,Breather Hose	1
YM***70	Splash-Guard	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Head : Exhaust Manifold And Muffler

YM***02	Stud	2
YM***80	Collar	1
YM***22	Stud	4
YM***02	Screw	4

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Komatsu : 3d82e-3a(S/N 00101-Up) : Cylinder Head : Rocker Arm

YM***02	Screw	6
YM***80	Spring	3
YM***40	Rocker Shaft	1
YM***52	Screw	2

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Electrical System

Komatsu : 3d82e-3a(S/N 00101-Up) : Electrical System : Alternator (20a)

YM***00	Stator Ass'Y	1
YM***10	Bearing,Ball	1
YM***02	Alternator A. (20a)	1
YM***00	Nut,Ball	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Electrical System : Alternator And Mounting (20a)

YM***70	Stud	1
YM***02	Nut	1
YM***52	Screw	1
YM***31	Adjuster, Belt	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Electrical System : Safety Relay? Current Limiter? Charge Indicator? Grow Relay And Timer

YM***21	Indicator, Charging	1
YM***20	Timer,Solenoid	1
YM***10	Relay,Stop Solenoid	1
YM***11	Limiter, Current	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Electrical System : Starting Motor And Mounting

YM***52	Bolt Plated	2
(Y***0)	Starting Motor Ass'Y,(See Fig.A6210-B0a2a)	1
(Y***0)	Starting Motor Ass'Y,(See Fig.A6210-B0a2)	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Electrical System : Starting Motor(#00101-09680)

YM***20	Pinion,Pinion	1
YM***80	Catch	1
YM***70	Nut	1
YM***30	Bearing,Ball	1

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Fuel System

Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Filter And Piping

YM***70	Union	1
YM***40	Lever	1
YM***00	O-Ring (Kit)	1
YM***50	Cartridge	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2)

YM***40	Lever,Control	1
YM***30	Spacer,Lever Shaft	1
YM***02	Nut	1
YM***30	Solenoid,Engine Stop	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2)

YM***01	Weight Assembly., Governor	1
YM***50	Angleich Ass'Y	1
YM***00	Washer,Spring	1
YM***40	Link? L=30.5,L=30.5 (Mark 05)	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Injection Pump (Pump) (1/2)

YM***50	Kit, Shim	1
YM***10	Plate? Caution	1
YM***50	Cover,Side	1
YM***90	Key,Woodruff	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Injection Pump (Pump) (2/2)

YM***70	Retainer, Spring	3
YM***00	Plunger W/Barrel	3
YM***02	Screw	2
YM***00	Valve,Delivery	3

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Injection Pump And Piping

YM***20	Retainer, Pipe	1
YM***60	O-Ring,Fuel Injection Pump	1
YM***20	Pipe,Injection? No.2	1
YM***10	Pipe,Injection? No.3	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Fuel Nozzle And Spill Pipe

YM***20	Spring	1
YM***00	Fuel Nozzle Ass'Y	3
YM***50	Nozzle, Assembly	1
YM***00	Fuel Injection Nozzle, Assembly	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Fuel System : Water Separator

YM***00	Gasket	2
YM***00	O-Ring (Kit)	1
YM***50	Plug,Air	2
YM***10	Bowl, Fuel Strainer	1

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Lubricating Oil System

Komatsu : 3d82e-3a(S/N 00101-Up) : Lubricating Oil System : Lubricating Oil Filter

YM***50	Nut	1
YM***02	Bolt Plated	3
YM***00	Valve,Relief	1
YM***01	Support	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Lubricating Oil System : Lubricating Oil Pump And Piping

YM***50	Oil Pressure Transmitter	1
YM***00	Oil Pump Ass'Y	1
YM***02	Seal,Ring (Kit)	2
YM***41	Gasket (Kit)	1

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Tool And Kit

Komatsu : 3d82e-3a(S/N 00101-Up) : Tool And Kit : Gasket Kit

YM***60	O-Ring,Fuel Injection Pump	1
YM***00	Gasket Kit	1
YM***40	O-Ring,Drain Plug	1
YM***50	Gasket,(Square Type)	1

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Komatsu : 3d82e-3a(S/N 00101-Up) : Tool And Kit : Tool

YM***60	Wrench,Fuel Filter? Water Separator	1
YM***50	Screw Driver	1
YM***20	Flex Horn (Option.)	1
YM***50	Wrench,Oil Filter? (Pc38uu)	1

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3D82E-3A(S/N 00101-UP) serial number reference

The engine data plate is a metal tag on the left side of the engine block, listing manufacturer, full model code (3D82E-3A), and serial number. If the plate is damaged, missing, or covered in grease and grime, the serial is also stamped directly into the engine block as a backup. Unlike whole-machine PINs, this small industrial engine uses a straight numeric serial sequence with no separate 3-letter regional prefix, so "00101-UP" identifies the entire production run of this configuration rather than one of several coded sub-ranges.

Prefix	Identifies	Notes
00101-UP	3D82E-3A base production block (no letter-code sub-split documented)	Direct-injection 3-cylinder diesel in the Komatsu 68E-88E small industrial engine family, 1.425 L displacement (82 mm bore x 90 mm stroke). Fitted as original power in the Komatsu PC15-3, PC20-7, PC25-1, and PC30-7 compact excavators. The -3A suffix marks this naturally aspirated base configuration; the turbocharged 3D82AE line and the separately numbered 3D82E-3B are different engines, not variants of this block. Tracked as a single continuous numeric serial run starting at 00101; no parts listing or shop manual reviewed shows a further 3-letter regional/plant prefix split inside this block, unlike whole-machine PINs. Confirm with a dealer if working outside the excavator applications listed above.

Frequently asked questions

What engine is the Komatsu 3D82E-3A?

It is the engine itself: a vertical, water-cooled, four-cycle, naturally aspirated three-cylinder direct-injection diesel with an 82 mm bore and 90 mm stroke, displacing 1.425 L with an 18.0:1 compression ratio. It is part of Komatsu's 68E-88E small industrial diesel family and runs on a mechanical fuel-injection pump with no electronic engine controls.

What is the operating weight of the 3D82E-3A?

As a bare engine it has no machine operating weight to quote. Komatsu's dry weight for this engine is 138 kg (304 lb) or 155 kg (342 lb), depending on the flywheel-housing configuration fitted; check the engine data plate or your parts book to confirm which applies to your unit.

What replaced the 3D82E-3A?

Within the same "-3" generation Komatsu carried this bore and stroke through further lettered updates before moving the family to the "-5" generation and later the 82E-6/98E-6 series as fuel-injection and accessory-drive detail advanced. There is no single documented direct replacement; shops typically rebuild the original core or cross to a later-generation family engine depending on what the host machine needs.

What 3D82E-3A(S/N 00101-UP) owners discuss

What engine is actually inside a 3D82E-3A, and how does it relate to the other 82-series Komatsu codes floating around?

The 3D82E-3A is a three-cylinder, water-cooled, direct-injection diesel fitted to Komatsu compact excavators including the PC15-3, PC20-7, PC25-1, and PC30-7. Published output figures for this exact engine code are not consistent across sources, so treat any horsepower/kW number as approximate and check it against the machine's own engine plate rather than a generic spec sheet. Related 82mm-bore engines use different suffixes for different hosts: the -3B code and a separate turbocharged AE-suffixed variant power other machines in the same size class. Same bore family, different calibration and hardware. Do not swap specs or parts across codes without checking the tag on the block.

This engine is a pain to start cold. What is the actual fix path?

Cold starting relies on a glow plug relay and individual glow plugs preheating the chambers, standard for a small industrial diesel of this generation. When cold starts get sluggish or stop working altogether, the fix path starts at the glow system, not the injection pump: check the relay and its wiring for corrosion or a bad ground, then confirm each glow plug is actually heating before condemning anything further downstream. A weak or marginal battery mimics a glow-plug fault on an engine this small, so load-test it before chasing electrical gremlins. Because this is a preheat/electrical circuit feeding into the fuel start sequence, have your dealer verify relay output and plug draw with a proper meter before replacing parts on a guess.

Engine cranks fine but will not fire, or dies under load. Fuel pump or something simpler?

The injection pump and injectors get blamed first, but the more common point of failure sits upstream: the inline fuel strainer(s) between tank and pump. Factory strainers use a fine brass screen that clogs with tank sediment or stale fuel varnish and can be cleared by blowing compressed air backward through the outlet side. Aftermarket replacement filters use a paper element instead, which loads up differently and can mask the same symptom. Rule out air getting pulled in at a loose fitting or a cracked pickup line before condemning the injection pump, and bleed the low-pressure side any time the fuel system has been opened.

Hydraulic pump whines when I first start up in cold weather. Normal, or something to worry about?

A whine that shows up cold and fades once the machine is up to temperature is typically cavitation, either from thick cold oil or a partly restricted suction strainer, not a failing pump. This platform has no dedicated warm-up cycle. Standard practice is to run one function gently against relief for a minute or two, then cycle the other functions lightly to circulate warmed oil before putting the machine under load. If the whine does not fade once the oil reaches operating temperature, or it gets worse instead of better, that points to internal pump wear or contamination, and the pump and valve section need a look, not just a warm-up.

Track keeps going loose no matter how much I grease the tensioner. What is really going on?

A track that will not hold tension after regreasing usually traces to a leaking tensioner cylinder seal bleeding pressure off internally, sometimes made worse by a loose grease-fitting bolt letting air into the circuit. Regreasing buys time but does not fix a seal that has already gone. Separately, this model's rubber track lug and guide pattern changed partway through its serial number run, so replacement tracks need to be matched to the machine's serial number, not just the model name, or they will not seat on the rollers correctly. Tensioner assemblies carry significant spring preload internally. Have your dealer verify before anyone disassembles one.

One track crawls slower than the other, or locks up entirely. Is that the track motor?

Uneven crawl speed or a track locking on one side while the other drives normally usually isolates to the travel motor or its hydraulic circuit, not the track or rollers. Oil weeping at the final drive, especially fluid showing up behind the sprocket, signals a failed final-drive seal letting gear oil escape, and points at the travel motor or reduction unit needing attention rather than a simple hose or fitting fix. Have your dealer verify circuit pressures before swapping a travel motor outright, since a restricted line or a failing control valve can produce the same symptoms as a bad motor.

What should I actually check before buying a used machine running this engine?

Start at the undercarriage: look for track wear past half the original lug depth, cracking, and sprocket teeth that have gone flat-topped instead of staying pointed, since undercarriage repair is the single biggest cost on a machine this size. Check behind the sprockets and around the final drives for oil weep, a sign of seal failure. Look over the boom and arm pins and welds for repair marks or elongation that hint at abuse or a prior structural fix. Start the engine cold if you can and watch the exhaust: white smoke that clears in a few seconds is normal cold-start behavior, but smoke that lingers points at a glow plug or injector problem, black smoke means overfueling, and blue smoke means worn rings. Cycle every hydraulic function through full travel and watch for delayed response, drift, or seep at the cylinder rod seals. Given how old this platform is, also confirm a dealer or independent shop nearby can still get parts for it before you commit.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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