Komatsuengine(no series)

Komatsu 4D84E-3E(S/N 03508-UP)

Maintenance schedule, common problems & OEM parts breakdown

Search live 4D84E-3E(S/N 03508-UP) parts

The Komatsu 4D84E-3E (S/N 03508-up) is a bare industrial diesel engine, not a complete machine: a compact, water-cooled, naturally aspirated 4-cylinder diesel of 1.995 L displacement (84 mm bore x 90 mm stroke), rated around 30 kW (40 hp) at 3000 rpm on its base spec sheet. It belongs to Komatsu's 4D84E small-diesel line (68E-88E engine series) and shares its core architecture with the Yanmar-built 4TNE84 badge-equivalent block. Dry weight for the base engine assembly runs about 170 kg (375 lb). Komatsu built this block across a run of lettered arrangement suffixes -3B, -3C, -3D, and this -3E, which shares its serial break with the -3D arrangement immediately before it. As an OE power unit it was installed in late-1990s to early-2000s compact construction equipment: mini excavators in roughly the 4 to 5 tonne class, compact and skid-steer loaders, small backhoes, and portable drill rigs, with installed output tuned per host, up to about 36 kW (48.5 hp) on some skid-steer builds.

Across the -3B through -3E run, Komatsu mostly changed accessory fitment, mounting, cooling circuit, and governor calibration rather than the core block; bore, stroke, displacement, and compression ratio stayed constant the whole way, and a turbocharged S-prefix sibling covered the forced-induction version at the same displacement. Being mechanically governed with indirect injection, it predates any electronic engine controls, so there is no fault-code system to lean on, just gauges, warning lamps, and hands-on checks. That simplicity, and the fact that it still turns up as a swap-in power unit and rebuild-kit candidate for aging compact excavators and skid steers of this era, is what keeps it relevant in the parts and used-equipment market today. Complete used or remanufactured units and overhaul kits remain sourced for it well after the host machines it powered have themselves gone out of production. Always confirm the exact suffix and serial break against the host's own parts book before ordering, since fitment details shift by suffix even though the base engine reads the same across the family.

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 4D84E-3E(S/N 03508-UP) specifications

Engine

Engine family	4D84E-3E is one arrangement of the Komatsu 4D84E engine series (68E-88E group), alongside 4D84E-3B, 3C and 3D. All arrangements share the same base block; the suffix denotes the equipment application/build arrangement, not a different displacement.
Type	Vertical in-line 4-cycle water-cooled diesel, naturally aspirated, indirect injection with swirl pre-combustion chamber
Cylinders	4
Bore x stroke	84.0 mm x 90.0 mm (3.30 in x 3.54 in)
Displacement	1.995 L (121.7 cu in)
Compression ratio	18:1 (listed as 18.5:1, effective 16.7:1, on some spec sheets)
Gross power (spec-sheet rating)	approx. 30.1 kW (40.4 hp) at 3000 rpm, naturally aspirated baseline rating for this engine block
Installed power (varies by host machine)	As installed and governed in host equipment, rated output differs by arrangement - some skid-steer installations show a higher figure near 36 kW (48.5 hp) at a lower governed speed around 2600 rpm. Treat power/speed as arrangement-specific; confirm against the exact machine or arrangement nameplate.
Peak torque	126.8 Nm (93.5 lb-ft)
Governor	Mechanical centrifugal, all-speed type
Emissions certification	Not documented for this exact serial range - this is an older mechanically governed, indirect-injection design that predates modern electronic emissions tiers. Verify certification status with your dealer if required for your use case.

Weights

Dry engine weight	approx. 170 kg (375 lb) for the base engine assembly, without host-machine mounts, ballast, or accessories
Operating/shipping weight	Not applicable - this is a bare engine listing, not a complete machine. Operating and shipping weight are set by the host equipment, not the engine alone.
Ground pressure	Not applicable to a standalone engine

Dimensions

Length	approx. 658 mm (26.0 in), flywheel housing to fan, base configuration
Width	approx. 499 mm (19.7 in)
Height	approx. 618 mm (24.4 in)
Note	External dimensions shift with fan, alternator, and accessory-drive configuration, which differ by arrangement/host machine. Figures above reflect the base naturally aspirated engine platform.

Performance

Rated (max) speed	3000 rpm
Fast idle	approx. 2875 rpm
Slow idle	approx. 950 rpm
Firing order	1-3-4-2
Rotation	Counterclockwise, viewed from the flywheel
Class-relevant performance	Travel speed, drawbar, lift, and dig figures do not apply to a bare engine assembly - those depend on the host machine's driveline and are published on that machine's own spec sheet.

Service capacities (summary)

Engine oil	approx. 5.3 to 5.6 L (5.6 to 5.9 US qt)
Coolant	approx. 6.1 L (5.8 US qt) on full-system figures; some listings show a smaller radiator-only figure near 2.6 L - use the full cooling-system figure for service planning and confirm with your dealer
Fuel tank	Not applicable - fuel tank capacity is set by the host machine, not the bare engine

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

4D84E-3E(S/N 03508-UP) fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase (with oil filter change)	5.8 L max, 2.3 L between low and high dipstick marks (1.53 US gal max, 0.61 US gal service range)	API Service Classification CC or higher. Grade by ambient temperature: SAE 5W-20 or 10W-30 for cold climates down to about -30 C (-22 F); SAE 10W or 20W for cool ranges; SAE 20W-20 or 20W-30 for moderate climates; SAE 20W-40 for hot climates up to about 40 C (104 F). The engine builder's documentation for this model does not call out a proprietary oil line by name.
Cooling system	2.7 L, engine block and head only; excludes radiator, hoses, and any host-machine circuit volume (0.71 US gal)	Soft, clean water with a quality antifreeze / anti-corrosion coolant additive; never fill with hard water. Drain and refill at 400-hour or 1-year intervals, whichever comes first. No branded coolant is named in the engine builder's documentation; a dealer-supplied antifreeze and rust inhibitor is acceptable.
Fuel system	No dedicated fuel tank on the bare engine; tank capacity is set by the host machine it is installed in - check that machine's own operation manual.	Diesel fuel oil equivalent to or better than ISO 8217 DMA, or BS 2869 Part 1 Class A1 / Part 2 Class A2, minimum cetane number 45.
Transmission, final drives, hydraulic system and tank, axles/differentials	Not applicable. This is a bare industrial/OEM diesel engine block with no integrated transmission, final drive, hydraulic system, or axle. Those systems belong to the machine the engine is installed in; consult that machine's own operation and maintenance manual.	Not applicable to the engine itself.
Grease	Not specified in the engine operation and maintenance manual; the bare engine has no chassis grease points of its own.	None specified for the engine. Follow the host machine's grease points and intervals per that machine's own manual.

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

Komatsu 4D84E-3E(S/N 03508-UP) maintenance schedule

Service interval	Tasks
Every 50 h	Check engine oil level before starting; top up to the upper dipstick mark, never above it. Check coolant level in the reservoir or radiator; top up with a clean water and antifreeze mix, never straight or hard water. Drain water and sediment from the fuel tank and water separator. Inspect for fuel, oil, and coolant leaks around the block, filter housings, and hose connections. Check fan belt and alternator belt tension and condition; adjust or replace if cracked or glazed. Clean the air cleaner element more often in dusty conditions and check the restriction indicator.
Every 250 h	Change engine oil and replace the oil filter element. Replace the fuel filter element. Check battery electrolyte level and clean and tighten terminal connections. Check and adjust fan belt and alternator belt tension. Clean or replace the air cleaner element as needed.
Every 500 h	Check and adjust valve clearance at the rocker arms. Check fuel injection timing against factory spec. Inspect injector nozzles for spray pattern and opening pressure; clean or recondition as needed. Drain and refill the cooling system with a fresh coolant mix at this point or by 400 hours, whichever comes first. Inspect the radiator core and hoses for cracking, clogging, or leaks and clear debris from the fins. Check the exhaust manifold and piping for leaks and secure mounting.
Every 1,000 h	Check and adjust the water pump for wear, play, and leakage. Check the crankshaft pulley and vibration damper for looseness or wear. Check cylinder head bolt torque. Check starter motor and alternator brushes, bearings, and wiring for wear or corrosion. Check the glow plug/preheat circuit and relay operation. Check governor linkage and throttle mechanism for free movement and correct adjustment.
Every 2,000 h	Check cylinder compression on all cylinders and compare against factory spec. Inspect or recondition the fuel injection pump. Check valve seats and guides for wear; recut or replace as needed. Check main and connecting rod bearing clearances. Flush and pressure-test the entire cooling system. Check the flywheel housing and coupling for wear or looseness.
Every 4,000 h	Perform a full engine overhaul: inspect cylinder liners, pistons, and rings for wear and replace as a set. Replace main and connecting rod bearings. Recondition or replace the injection pump and injector nozzles together. Resurface or replace the cylinder head if warped or cracked. Replace engine mounts, hoses, and drive belts as a preventive set. Recalibrate the governor and injection timing after rebuild before returning to service.

Servicing the 4D84E-3E(S/N 03508-UP) beyond the schedule

Predictive Maintenance & Fluid Analysis

This engine has no ECM and no stored fault codes, so predictive care relies on physical checks. Track oil condition through the 250-hour change interval and watch for a diesel smell or milky sheen that flags injector or coolant leakage into the crankcase. Sample coolant at the 400-hour drain point instead of waiting for a temperature spike; this small water-cooled block runs a tight coolant volume and overheats fast once fouled. Watch fuel filter intervals closely; injector wear shows up first as rough idle and fading power, well before failure.

Corrective & Common Repairs

Hard cold starts and slow cranking on this naturally aspirated, indirect-injection block trace most often to a weak glow plug or failing preheat relay, not the injection pump. Check glow-plug continuity and relay operation first. Overheating tends to warp or crack the cylinder head rather than blow the gasket, usually from a clogged radiator core and low coolant. Injector wear shows up as rough idle and fading power well before failure. On host machines built around this block, inspect the rubber flywheel-to-pump coupling for cracking on unexplained vibration.

Overhaul & Rebuild Points

Full rebuilds on this block center on the piston-and-ring set, piston pins and retainers, main and rod bearing sets, thrust washers, and crank seals. These match the wear items reman kits target across the 4D84E/Yanmar-derived family. Bore, stroke, and compression ratio stay constant across the B-through-E arrangement suffixes, so a core engine from a same-displacement sibling can donate a block or head in a pinch, but confirm accessory drive and cooling-circuit fitment match before swapping. Check cylinder head flatness and valve seats any time the head comes off.

Seasonal & Environment Servicing

Switch engine oil grade by season on this indirect-injection block: thinner 5W-20/10W-30 down to about -30 C (-22 F), heavier 20W-40 in hot climates up to 40 C (104 F), per the factory oil chart. Host machines built around this block run compact, low-airflow cooling packages, so a core clogged with mud, grass, or chaff is the top overheating cause in brush and mowing work; clean it more often than the standard interval. Run a proper antifreeze mix year round and never fill the cooling system with untreated water.

4D84E-3E(S/N 03508-UP) common service parts

Part number	Part	Notes
(YM129052-55620)	Fuel Filter Ass'Y,(See Fig.A4110-B0a6)	Fuel system service	Check fitment →
YM129100-55650	Element,Fuel Filter	Fuel system service	Check fitment →
YM129052-55620	Fuel Filter Ass'Y	Fuel system service	Check fitment →
YM102103-55520	O-Ring,(For Fuel Filter)	Fuel system service	Check fitment →
YM119808-12520	Element,Outer	Scheduled service item	Check fitment →

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

4D84E-3E(S/N 03508-UP) fault codes & troubleshooting

Code	Meaning	Likely cause	What to do
Engine Oil Pressure Warning Lamp (red)	Engine lubrication oil pressure has dropped below the safe minimum	Low oil level, clogged oil filter, worn oil pump, failed oil pressure switch, or worn bearings	Stop the engine immediately, check oil level and condition, inspect the oil pressure switch and wiring before restarting
Coolant Temperature Warning Lamp (red)	Coolant temperature has exceeded the safe operating range	Low coolant level, clogged radiator fins, failed thermostat, loose or worn fan belt, or a faulty temperature sender switch	Idle down and let the engine cool, check coolant level once safe, clean the radiator core, check belt tension and thermostat operation
Charge (Alternator) Warning Lamp (red)	Charging circuit is not supplying adequate voltage to the battery	Loose or worn alternator belt, failed alternator, corroded or loose wiring connections, or a weak battery	Check belt tension and condition, inspect wiring and battery terminals, test alternator output
Air Cleaner Restriction Indicator	Intake air filter element is clogged, restricting airflow to the engine	Dirty or saturated paper element from dusty operating conditions	Service or replace the air filter element and reset the indicator
Fuel Level Warning Lamp	Fuel tank level has reached the low-fuel threshold	Tank genuinely low on fuel, or a faulty float/sender unit giving a false reading	Refuel and recheck; if the lamp stays on with a full tank, check the sender unit
Preheat (Glow) Indicator Lamp	Intake air preheating aid is active to assist cold starting	Normal cold-start indicator; excessive preheat time or no improvement in cold starting points to a failed heater element or relay	Let the preheat cycle finish before cranking; if preheat time is abnormally long or starting stays hard when cold, check the heater element, relay, and wiring

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

4D84E-3E(S/N 03508-UP) attachments & work tools

OEM industrial power unit, not a field-attachment machine

This is a bare engine assembly with no chassis, hull, or carrier of its own. It is sold and installed as an OE power unit inside other equipment, so classic work-tool attachments (buckets, grapples, hammers, quick couplers) do not apply to it.

Aspiration / induction arrangement

This engine runs naturally aspirated. The same base architecture was also factory-built with a turbocharged induction arrangement (carrying an S-prefix engine code) as the forced-induction counterpart at this displacement; no turbo kit is fitted to this naturally aspirated arrangement.

Suffix / spec revision variant

The engine family was released through a run of lettered spec revisions sharing one base design. This -3E revision carries the same serial break as its immediate -3D-suffix sibling, pointing to a running production/spec update rather than a distinct host tie or configuration change.

Accessory drive

Alternator and water (coolant) pump are belt-driven off the crankshaft pulley, the standard industrial accessory-drive layout for this engine family. No dedicated power-take-off shaft or attachable-implement drive is documented for this variant.

Cooling package

Delivered with an engine-mounted, belt-driven pusher-type cooling fan and matching radiator sized to the block as part of the complete engine assembly. No alternate remote-mount, keel-cooled, or heat-exchanger cooling package is documented for this specific variant.

Documented host application class

This general engine family (the same small-displacement industrial diesel line this model belongs to) is documented in OEM literature as power for compact construction equipment such as mini excavators and compact loaders. No dedicated marine, genset, or stationary-pump package is documented tied specifically to this exact model/serial range.

All 4D84E-3E(S/N 03508-UP) assemblies by section

Every catalogued assembly group for the Komatsu 4D84E-3E(S/N 03508-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Engine

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Air Cleaner And Mounting (Double Element)(#12182-)

YM***90	Gasket,(Not Shown)	1
YM***60	Support	1
YM***60	Silencer	1
YM***10	Case, Assembly	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Air Cleaner And Mounting(#06291-)

YM***90	Gasket,(Not Shown)	1
YM***60	Support	1
YM***60	Silencer	1
YM***10	Case, Assembly	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Air Intake Manifold And Connection

YM***02	Bolt Plated	6
YM***02	Screw	2
YM***00	Heater,Intake Air	1
YM***10	Gasket,Heater (Kit)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Alternator (40a) (Inner Parts)(#06291-)

YM***20	Rear Bracket Ass'Y	1
YM***30	Front Bracket Ass'Y	1
YM***00	Rotor Ass'Y	1
YM***40	Pulley	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Alternator And Mounting (40a)(#06291-)

YM***00	Adjuster, Belt	1
YM***02	Nut	1
YM***02	Screw	1
YM***40	Screw	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Camshaft And Tappet

YM***80	Camshaft Ass'Y	1
YM***01	Gear Ass'Y,Camshaft	1
YM***50	Bearing, Thrust	1
YM***62	Bolt,(For Shipping)	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Crankshaft(#06291-)

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

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Cylinder Block

YM***60	Cylinder Block, Assembly	1
YM***00	Plug	1
YM***50	Plug	1
YM***20	Screw	10

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Cylinder Block Accsessory(#06291-)

YM***50	Oil Pressure Transmitter	1
YM***20	Plug,Drain(Without Oil Cooler Type)	1
YM***62	Bolt,(For Shipping)	1
YM***10	Guide,Level Gauge	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Cylinder Head

YM***80	Retainer, Spring	8
YM***40	Seal,Valve? Exhaust (Kit)	4
YM***10	Valve,Exhaust	4
YM***10	Guide,Valve? Exhaust	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Cylinder Head Cover(#06291-)

YM***20	Cover, Breather	1
YM***70	Clamp	1
YM***51	Cap, Lub. Oil Supply	1
YM***90	Retainer	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Drive Gear (Epa Spec.)(#8478-)

YM***02	Nut	1
YM***01	Idler Gear Ass'Y,Idler	1
YM***52	Screw	2
YM***00	Flange, Assembly	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Drive Gear(#06291-12181)

YM***02	Nut	1
YM***01	Idler Gear Ass'Y,Idler	1
YM***00	Gear,Injection Pump	1
YM***52	Screw	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Drive Gear(#12182-)

YM***01	Idler Gear Ass'Y,Idler	1
YM***52	Screw	2
YM***20	Bush,Idle Gear (Repair Part)	1
YM***61	Shaft,Idler	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Electrical Parts (Forwerded Individually Parts)(#06291-)

YM***00	Relay Ass'Y,Safety	1
YM***20	Timer,Solenoid	1
YM***10	Relay,Stop Solenoid	1
YM***20	Time Switch	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Exhaust Manifold(#06291-)

YM***02	Screw	4
YM***02	Nut	2
YM***00	Cover	1
YM***10	Gasket (Kit)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Flywheel And Flywheel Housing(#06291-)

YM***02	Screw	4
YM***90	Flywheel Ass'Y	1
YM***70	Screw	6
YM***80	Parallel Pin	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Front Cover(#06291-12181)

YM***90	Front Cover Ass'Y	1
YM***51	Cap, Lub. Oil Supply	1
YM***00	Clip,Breather Hose	1
YM***40	O-Ring,Drain Plug	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Front Cover(#12182-)

YM***02	Bolt Plated	2
YM***51	Cap, Lub. Oil Supply	1
YM***00	Clip,Breather Hose	1
YM***40	O-Ring,Drain Plug	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Front Hanger

YM***00	Hook,Front	1
YM***42	Screw	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Filter And Piping(#06291-)

YM***70	Union	1
YM***02	Bolt Plated	2
YM***20	Pipe	1
YM***00	Pipe, Assembly	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Filter(#06291-)

YM***00	O-Ring (Kit)	1
YM***70	Lever	1
YM***80	Cup, Strainer	1
YM***50	Element,Fuel Filter	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts) (Epa Spec.)(#8478-)

YM***40	Lever,Control	1
YM***30	Spacer,Lever Shaft	1
YM***02	Nut	1
YM***50	Bolt, Revol. Limit	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)(#06291-12181)

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (1/2) (Inner Parts)(#12182-)

YM***40	Lever,Control	1
YM***30	Spacer,Lever Shaft	1
YM***02	Nut	1
YM***50	Bolt, Revol. Limit	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts) (Epa Spec.)(#8478-)

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

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)(#06291-12181)

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

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Governor) (2/2) (Inner Parts)(#12182-)

YM***50	Angleich Ass'Y	1
YM***00	Washer,Spring	1
YM***40	Link? L=30.5,L=30.5 (Mark 05)	1
YM***50	Spring,Fuel Control	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts) (Epa Spec.)(#8478-)

YM***50	Kit, Shim	1
YM***10	Plate? Caution	1
YM***02	Nut	1
YM***90	Key,Woodruff	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)(#06291-12181)

YM***50	Kit, Shim	1
YM***10	Plate? Caution	1
YM***90	Key,Woodruff	1
YM***30	Spacer? T=3.25	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (1/2) (Inner Parts)(#12182-)

YM***50	Kit, Shim	1
YM***10	Plate? Caution	1
YM***02	Nut	1
YM***90	Key,Woodruff	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts) (Epa Spec.)(#8478-)

YM***70	Retainer, Spring	4
YM***00	Rack,Control	1
YM***02	Screw	2
YM***30	Spacer,Spring	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)(#06291-12181)

YM***70	Retainer, Spring	4
YM***00	Rack,Control	1
YM***02	Screw	2
YM***30	Spacer,Spring	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump (Pump) (2/2) (Inner Parts)(#12182-)

YM***70	Retainer, Spring	4
YM***00	Rack,Control	1
YM***02	Screw	2
YM***30	Spacer,Spring	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump And Piping (Epa Spec.)(#8478-)

YM***60	O-Ring,Fuel Injection Pump	1
YM***02	Nut	3
YM***31	Pipe,No.1	1
YM***20	Pipe,No.3	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump And Piping(#06291-12181)

YM***60	O-Ring,Fuel Injection Pump	1
YM***02	Nut	3
YM***31	Pipe,No.1	1
YM***20	Pipe,No.3	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Injection Pump And Piping(#12182-)

YM***60	O-Ring,Fuel Injection Pump	1
YM***31	Pipe,No.1	1
YM***60	Nut	3
YM***20	Pipe,No.3	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Fuel Nozzle And Spill Hose(#06291-)

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

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Gasket Kit(#06291-)

YM***60	O-Ring,Fuel Injection Pump	1
YM***40	Seal,Valve? Exhaust (Kit)	4
YM***20	Gasket,Water Pump	1
YM***40	Gasket Kit	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Lubricating Oil Pump(#06291-)

YM***50	Pipe,Oil	1
YM***91	Tube,Oil Suction	1
YM***30	Bolt, Assembly	1
YM***02	Seal,Ring (Kit)	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Muffler And Mounting(#06291-)

YM***02	Nut	1
YM***01	Gasket (Kit)	1
YM***11	Muffler	1
YM***90	Muffler	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Muffler And Mounting(#12182-)

YM***02	Nut	4
YM***01	Gasket (Kit)	1
YM***90	Clamp Ass'Y	1
YM***20	Stud Bolt	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Oil Filter(#06291-)

YM***50	Nut	1
YM***00	Valve,Relief	1
YM***22	Screw	3
YM***01	Support	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Oil Pan

YM***30	Spacer	1
YM***52	Screw	2
YM***52	Screw	24
YM***40	Plug,Drain	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : P.P.C. Pump And Mounting(#06291-)

YM***20	Pump Ass'Y,Hydraulic	1
YM***02	Nut	2
YM***64	Bearing,Ball	2
YM***81	Gasket (Kit)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Piston And Connecting Rod

YM***00	Screw	2
YM***00	Crank Pin Metal A. (Std)	1
YM***01	Assembly, Piston (+0.25 mm)	4
YM***50	Ring Set (+0.25 mm)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Rear Hanger

YM***00	Hook,Front	1
YM***42	Screw	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Rocker Arm

YM***02	Nut,Rock	3
YM***02	Screw	7
YM***80	Spring	4
YM***50	Rocker Arm Ass'Y	8

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Starting Motor (Inner Parts)(#06291-12181)

YM***20	Holder Ass'Y,Brush	1
YM***50	Stopper Ass'Y	1
YM***20	Pinion, Assembly	1
YM***90	Bracket	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Starting Motor (Inner Parts)(#12182-)

YM***80	Housing	1
YM***90	Clutch, Starter	1
YM***30	Bolt	2
YM***20	Pinion,Pinion	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Starting Motor And Mounting(#06291-12181)

YM***52	Bolt Plated	2
YM***02	Nut,Rock	1
YM***00	Washer,Spring	1
(Y***0)	Starting Motor Ass'Y,(See Fig.A6210-B0a2)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Starting Motor And Mounting(#12182-)

YM***52	Bolt Plated	2
YM***02	Nut,Rock	1
YM***00	Washer,Spring	1
(Y***0)	Starting Motor Ass'Y,(See Fig.A6210-B0a2a)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Tool(#06291-)

YM***20

Flex Horn (Option.)

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Air Con Spec.) (Pulley Dia 110mm)(#12182-)

YM***40	Joint	1
YM***22	Screw	2
YM***02	Screw	4
YM***11	Gasket (Kit)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Dust And Proof) (Pulley Dia 120mm)(#12182-)

YM***40	Joint	1
YM***22	Screw	2
YM***02	Screw	4
YM***11	Gasket (Kit)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Pulley Dia 110mm) (Epa Spec.)(#7495-)

YM***40	Joint	1
YM***90	V-Belt	1
YM***02	Bolt Plated	2
YM***20	Gasket,Water Pump	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Water Pump And Cooling Fan (Pulley Dia 130mm)(#06291-)

YM***40	Joint	1
YM***02	Bolt Plated	2
YM***22	Screw	2
YM***20	Gasket,Water Pump	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : 4d84e-3e(S/N 03508-Up) : Engine : Water Sepatator(#06291-)

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

See all parts with full part numbers in Heavy Parts AI →

Frequently asked questions

What engine does the Komatsu 4D84E-3E (S/N 03508-up) use?

It is the engine itself: a naturally aspirated, indirect-injection 4-cylinder diesel of 1.995 L displacement (84 mm bore x 90 mm stroke), rated at roughly 30 kW (40 hp) at 3000 rpm on the base spec sheet. It shares its core architecture with the wider Komatsu 4D84E family and the Yanmar-built 4TNE84 badge-equivalent block. Installed and governed output can run higher, to around 36 kW (48.5 hp), on some host machines, so treat the exact rating as arrangement-specific and confirm it against your machine's own nameplate.

What is the operating weight of the 4D84E-3E (S/N 03508-up)?

Operating weight does not apply to this listing since it is a bare engine assembly, not a complete machine. The dry engine itself weighs approximately 170 kg (375 lb) without mounts, ballast, or accessories. Total operating weight is set entirely by the host machine it powers, which for this small-diesel class typically runs a compact mini excavator, skid-steer loader, or backhoe in roughly the 3 to 5 tonne range. Check that machine's own spec sheet for its figure.

What replaced the 4D84E-3E in later Komatsu equipment?

There is no single documented direct successor tied to this exact arrangement and serial break. The 4D84E family itself progressed through lettered arrangement revisions (B through E) that mostly changed accessory fitment and governor calibration rather than the core block, alongside a turbocharged S-prefix sibling built on the same displacement. As Komatsu's compact equipment line moved toward newer emissions-certified small-diesel platforms, this mechanically governed, indirect-injection design aged out of production. Verify the exact replacement engine with your dealer for your specific host machine.

What 4D84E-3E(S/N 03508-UP) owners discuss

What engine is really behind the 4D84E-3E (S/N 03508-up), and does it show up under a different name in parts research?

This block traces to the same small-diesel lineage Komatsu sourced through its industrial engine arrangement rather than an in-house clean-sheet design; expect cross-reference hits under a different manufacturer's part numbering alongside the Komatsu 4D84E designation. The 3B/3C/3D/3E suffixes on this family mostly track application and accessory fitment (mounting, cooling circuit, governor setup) rather than a different core engine, so don't assume a spec called out for one suffix automatically carries to the 3E build without checking the accessory list. The same basic casting also turns up outside Komatsu-badged machines, so don't be surprised when a cross-reference search returns a compact track-loader or skid-steer part instead of an excavator part.

Cold mornings, hard starting, glow plug behavior — what's normal versus a fault?

Slow cranking and hard cold starts on this engine family are usually traced to a weak glow plug or a failing glow plug relay/control box, not the injection pump. A ticking or priming noise right after start-up is commonly just the fuel pump re-priming the filter after air worked into the lines overnight — not a mechanical fault by itself. Check glow plug continuity and relay operation before condemning injectors or the pump.

Is overheating and head-gasket failure a known weak point on this engine?

A warped or cracked cylinder head after sustained overheating is the failure mode most reported for this engine family, more often than a straightforward blown gasket. Compact machines built around this block don't move a lot of air across the radiator and oil cooler, so a debris-packed core (mud, grass, chaff) combined with a low coolant level is the usual root cause rather than a design flaw. White exhaust smoke paired with rising coolant temperature points to coolant reaching the combustion chamber — have a shop run a cooling-system pressure test and check the head for warpage before doing further work.

What fuel-system and driveline quirks come up repeatedly for this engine family?

Injector wear shows up as rough idle and a gradual power drop well before outright failure, and it's accelerated by contaminated fuel or stretched filter-change intervals — regular fuel filter service is the cheapest insurance here. A soft rubber coupling between the engine flywheel and the main hydraulic pump on machines built around this block is a known wear item that cracks and perishes with age; it's worth a visual check any time there's unexplained driveline vibration or noise at the pump end of the engine.

What undercarriage or wear patterns come up on the machines this engine powers?

On the compact excavator hosts for this engine, worn carrier/track rollers letting the track ride up on the roller edge and slip off is a recurring complaint, and the center swing joint on the upper structure is packed with O-rings that age out and start weeping oil over time. Neither issue is engine-related, but inspectors typically flag both in the same walk-around as engine condition, so budget for them separately from any engine work.

What electrical or sensor issues actually apply to this engine, given it predates modern electronic controls?

This is a mechanically governed, pre-electronic-controls diesel, so there's no onboard fault-code system to lean on for diagnosis — a lack of stored codes is normal, not a sign the diagnostic tool is broken. Reported electrical issues on this platform center on the glow plug relay/control box and charge-light/alternator wiring, plus a sticky travel-speed solenoid on the drive valve body (on the excavator hosts) that can leave the machine stuck in one travel range. Chase wiring and relays first; there's no ECM to reflash or reset.

What should a buyer check before purchasing a used machine with this engine?

Pull the dipstick and check for a diesel smell or milky sheen in the oil (points to injector or fuel-pump leakage into the crankcase, or coolant intrusion), and check the coolant for an oil sheen in the other direction. Run the engine to full operating temperature and watch for a creeping gauge or white smoke under load. Cycle the machine through its full travel-speed range and full boom/swing motion listening for the swing-joint weeping or carrier-roller symptoms noted above, and confirm the glow plug cycle feels normal on a cold start. None of this replaces a shop compression test and a hydraulic pressure check — have your dealer verify engine and pump condition before final sign-off on a purchase.

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

Need a specific 4D84E-3E(S/N 03508-UP) part?

Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.

Search parts in the app