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Komatsu 3D84E Engine

The Komatsu 3D84E is a heavy-duty, vertical, 4-cycle, water-cooled industrial diesel engine. Manufactured to meet modern emissions standards, this naturally aspirated engine utilizes a high-strength cast iron cylinder block designed for compact heavy equipment, such as mini-excavators, loaders, and compact utility tractors. Known for its high reliability and service durability, it features an overhead valve design, an inline arrangement, and shares a highly optimized platform with Yanmar TNV/TNE series architectures.

Valve Configuration: Overhead Valve (OHV) pushrod-driven system. Total valves: 6 valves total (2 valves per cylinder: 1 intake, 1 exhaust). Maintenance: Clearance adjustments and valve seat lapping are required periodically at specific service thresholds to maintain proper seating contact and optimal compression. Bore: 84 mm (3.30 inches). Stroke: 90 mm (3.54 inches). Total displacement: 1.5 Liters (1496 cc). Configuration: 3 cylinders inline.

Fuel System: Mechanical direct or indirect injection system configurations. Injection pump: High-pressure inline multi-plunger pump or proprietary Yanmar MP-series pump. Governor type: Mechanical centrifugal variable-speed governor integrated directly within the pump house to maintain constant operational RPM under shifting load stresses. Pre-filtration: Configured with a dedicated inline water separator and a primary paper-element fuel filter assembly to protect high-precision pump internals from moisture and contamination.

Lubrication System: Full forced-pressure lubrication flow. Oil pump mechanism: Driven via an internal trochoid pump mounted to the gear case side. Filtration: Full-flow cartridge paper element filter combined with a built-in pressure regulating bypass valve. Cooling System: Forced liquid-circulation system utilizing a continuous bypass thermal loop. Circulation pump: Belt-driven centrifugal impeller water pump mounted to the front of the block. Temperature control: Wax-pellet type opening thermostat module regulating flow to the radiator assembly based on structural fluid temperatures.

General Technical Data

Engine Specifications

Engine Model ............... Komatsu 3D84E
Engine Type ............... 4-cycle inline 3-cylinder direct injection liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.31 (84.0)
Engine Stroke, in (mm) ............... 3.54 (90.0)
Displacement, cu.in (L) ............... 91.3 (1.496)
Rated Engine Power, hp (kW) ............... 22.0-33.0 (16.4-24.6)
Rated Engine Speed, rpm ............... 2000-3000
Peak Torque ............... 85-98 Nm (62.7-72.3 lb-ft) at 1600-1800 rpm
Idle Speed ............... 750-850 rpm
Aspiration Type ............... Naturally Aspirated
Operating Speed ............... 2400 rpm
Compression Ratio ............... 18.0:1-18.5:1
Firing Order ............... 1-3-2
Direction of Rotation ............... Counterclockwise viewed from flywheel
Combustion Chamber ............... Direct injection spherical type
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure forced lubrication
Oil Pump Type ............... Trochoid gear-driven
Oil Filter Type ............... Full-flow, spin-on cartridge
Cooling System ............... Liquid-cooled with radiator and forced circulation
Water Pump Type ............... Belt-driven, centrifugal
Air Cleaner Type ............... Dry dual-stage paper element
Emission Certification ............... US EPA and California ARB certified
Starting System ............... Electric Starter
Electrical System ............... 12V
Alternator Capacity, A ............... 40 or 55
Starter Motor Power, hp (kW) ............... 1.6-1.9 (1.2-1.4)

Fuel System

Fuel Injection Pump Type ............... Yanmar MP inline mono-plunger distributor pump
Governor Control System ............... Centrifugal weight mechanical control
Fuel Feed Pump Type ............... Mechanical diaphragm displacement type
Fuel Injection Nozzle Type ............... Hole type multi-orifice nozzle
Number of Injection Nozzle Holes ............... 4 or 5 holes per nozzle
Injection Nozzle Hole Diameter, in (mm) ............... 0.0078 (0.20)
Primary Fuel Filter Type ............... Spin-on element with transparent water separator
Secondary Fuel Filter Type ............... High efficiency micro-paper element
Fuel Supply Line Outer Diameter, in (mm) ............... 0.31 (8.0)
Fuel Return Line Outer Diameter, in (mm) ............... 0.23 (6.0)
Fuel Injection Opening Pressure, psi (MPa) ............... 2842-2987 (19.6-20.6)
Maximum Fuel Injection Pump Speed, rpm ............... 1500
Fuel Transfer Pump Pressure, psi (kPa) ............... 2.9-4.3 (20.0-30.0)
Governor Type ............... Mechanical centrifugal
Injection Timing Angle, deg BTDC ............... 12-16
Fuel Injection Line Thickness, in (mm) ............... 0.23 (6.0)
Fuel Tank Venting System ............... Atmospheric open breathing type
Maximum Fuel Temperature Inlet, F (C) ............... 122 (50.0)
Fuel System Priming Method ............... Manual priming lever on feed pump
Fuel Leakage Return Orifice Size, in (mm) ............... 0.019 (0.5)
Fuel Injection Pipe Length, in (mm) ............... 15.7 (400.0)
Fuel System De-aeration Method ............... Automatic air bleed system
Cold Start Enrichment Device ............... Thermal automatic advanced mechanism
Fuel Injection Pump Lubrication ............... Engine oil splash and pressure fed
Injection Valve Seat Angle, deg ............... 45 or 60
Fuel Grade Requirement ............... ASTM D975 No. 2-D ultra-low sulfur diesel

Dimensions and Weight

Overall Length, in (mm) ............... 21.8 (555)
Overall Width, in (mm) ............... 19.3 (490)
Overall Height, in (mm) ............... 24.4 (620)
Dry Weight, lbs (kg) ............... 298 (135)
Wet Weight, lbs (kg) ............... 322 (146)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (MPa) ............... 412 (2.84)
Compression Pressure, Limit, psi (MPa) ............... 327 (2.26)
Oil Pressure at Low Idle, psi (MPa) ............... 8.5 (0.06)
Oil Pressure at Rated Speed, psi (MPa) ............... 42.6-56.8 (0.29-0.39)
Coolant Operating Temperature, F (C) ............... 176-194 (80.0-90.0)
Thermostat Opening Initial Temperature, F (C) ............... 160 (71.0)
Thermostat Full Open Position Temperature, F (C) ............... 185 (85.0)
Radiator Cap Relief Valve Pressure, psi (kPa) ............... 12.8 (88.3)
Maximum Permissible Oil Temperature, F (C) ............... 230 (110.0)
Fan Belt Deflection, in (mm) ............... 0.39-0.59 (10.0-15.0)
Intake Valve Clearance, Cold, in (mm) ............... 0.0078 (0.20)
Exhaust Valve Clearance, Cold, in (mm) ............... 0.0078 (0.20)

Engine Oil and Coolant

Engine Oil Type .................. SAE 5W-30, SAE 15W-40, SAE 10W-30
API Service Classifications ......................... CH-4 or CI-4
Engine Oil Capacity with Filter, qt (L) ............... 5.8 (5.5)
Engine Oil Capacity, Sump Only, qt (L) ............... 5.0 (4.7)
Cooling Liquid Capacity, qt (L) ............... 5.3 (5.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 500 hours
Valve clearance adjustment ............... Every 1000 hours
Fuel system inspection ............... Every 1000 hours
Change coolant ............... Every 2000 hours
Compression test ............... Every 1000 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 150 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 3.3070-3.3074 (84.000-84.010)
Cylinder Bore Max Out-of-Roundness, in (mm) ............... 0.0007 (0.02)
Connecting Rod Small End Bushing I.D, in (mm) ............... 1.0246-1.0252 (26.025-26.038)
Connecting Rod Side Play Clearance, in (mm) ............... 0.0078-0.0157 (0.200-0.400)
Crankshaft Main Journal Diameter, in (mm) ............... 1.9665-1.9671 (49.950-49.962)
Crankshaft Main Journal Clearance, in (mm) ............... 0.0015-0.0026 (0.038-0.068)
Crankpin Outside Diameter, in (mm) ............... 1.8878-1.8883 (47.952-47.964)
Crankshaft Thrust End Play, in (mm) ............... 0.0043-0.0082 (0.110-0.210)
Piston Skirt Outside Diameter, in (mm) ............... 3.3047-3.3051 (83.940-83.950)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0019-0.0027 (0.050-0.070)
Piston Pin Bore Inner Diameter, in (mm) ............... 1.0236-1.0240 (26.000-26.010)
Piston Pin Outer Diameter, in (mm) ............... 1.0233-1.0236 (25.992-26.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0017 (0.045)
Top Ring Groove Side Clearance, in (mm) ............... 0.0027-0.0043 (0.070-0.110)
Second Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0031 (0.040-0.080)
Oil Ring Groove Side Clearance, in (mm) ............... 0.0007-0.0021 (0.020-0.055)
Top Ring End Gap, in (mm) ............... 0.0078-0.0157 (0.200-0.400)
Second Ring End Gap, in (mm) ............... 0.0078-0.0157 (0.200-0.400)
Oil Ring End Gap, in (mm) ............... 0.0078-0.0157 (0.200-0.400)
Cylinder Head Lower Surface Flatness Distortion, in (mm) ............... 0.0019 (0.050)
Cylinder Block Upper Surface Flatness Distortion, in (mm) ............... 0.0019 (0.050)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2740-0.2746 (6.960-6.975)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0009-0.0021 (0.025-0.055)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2736-0.2742 (6.950-6.965)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0013-0.0025 (0.035-0.065)
Intake Valve Sinkage Depth, in (mm) ............... 0.015-0.023 (0.40-0.60)
Exhaust Valve Sinkage Depth, in (mm) ............... 0.015-0.023 (0.40-0.60)
Valve Seat Angle, deg ............... 90 (45 face angle)
Valve Seat Contact Width, in (mm) ............... 0.042-0.057 (1.07-1.47)
Valve Spring Free Length, in (mm) ............... 1.488 (37.8)
Camshaft Main Journal Diameter, in (mm) ............... 1.7696-1.7706 (44.950-44.975)
Camshaft Main Journal Clearance, in (mm) ............... 0.0009-0.0035 (0.025-0.090)
Cam Lobe Height (Intake), in (mm) ............... 1.3405-1.3444 (34.050-34.150)
Cam Lobe Height (Exhaust), in (mm) ............... 1.3405-1.3444 (34.050-34.150)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.7858-0.7866 (19.960-19.980)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.7874-0.7885 (20.000-20.030)
Rocker Arm Shaft to Bushing Clearance, in (mm) ............... 0.0007-0.0027 (0.020-0.070)
Tappet Guide Bore Inner Diameter, in (mm) ............... 0.9448-0.9457 (24.000-24.021)
Tappet Body Outer Diameter, in (mm) ............... 0.9417-0.9425 (23.921-23.942)
Tappet Body to Guide Bore Clearance, in (mm) ............... 0.0022-0.0039 (0.058-0.100)
Idler Gear Shaft Outer Diameter, in (mm) ............... 1.4547-1.4557 (36.950-36.975)
Idler Gear Bushing Inner Diameter, in (mm) ............... 1.4566-1.4576 (37.000-37.025)
Idler Gear Shaft to Bushing Clearance, in (mm) ............... 0.0009-0.0029 (0.025-0.075)

Tightening Torques

Cylinder Head Bolts, lb-ft (Nm) ............... 54.3-57.9 (73.6-78.5)
Connecting Rod Capscrews, lb-ft (Nm) ............... 32.5-36.2 (44.1-49.0)
Crankshaft Main Bearing Caps Bolts, lb-ft (Nm) ............... 72.3-79.6 (98.1-107.9)
Flywheel Mounting Fasteners Bolts, lb-ft (Nm) ............... 61.4-68.7 (83.3-93.1)
Flywheel Housing Core Frame Fasteners, lb-ft (Nm) ............... 32.5-36.2 (44.1-49.0)
Crankshaft Pulley Front End Damper Bolt, lb-ft (Nm) ............... 83.1-90.4 (112.7-122.6)
Camshaft Thrust Bearing Plate Fasteners, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Camshaft Driven Timing Gear Hub Nut, lb-ft (Nm) ............... 57.9-65.1 (78.5-88.3)
Idler Gear Shaft Mounting Block Fast Fastener, lb-ft (Nm) ............... 32.5-36.2 (44.1-49.0)
Rocker Arm Shaft Support Bracket Bolts, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Rocker Arm Valve Adjusting Screw, lb-ft (Nm) ............... 10.1-13.7 (13.7-18.6)
Cylinder Head Valve Bonnet Cover Nut, lb-ft (Nm) ............... 7.2-9.4 (9.8-12.7)
Fuel Injection Pump Drive Gear Locking Nut, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Fuel Injection Pump Bracket Flange Fasteners, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Fuel Injection High Pressure Line Pipe Nuts, lb-ft (Nm) ............... 21.7-25.3 (29.4-34.3)
Fuel Injector Assembly Clamp Hold-down Bolt, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Fuel Leakage Return Line Overflow Pipe Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Fuel Feed Supply Pump Body Fasteners, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Oil Pan Outer Sump Fasteners, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Oil Drain Plug Component Fastener, lb-ft (Nm) ............... 36.2-43.4 (49.0-58.8)
Oil Pressure Relief Valve Main Body, lb-ft (Nm) ............... 28.9-36.2 (39.2-49.0)
Oil Pressure Regulator Spring Plug, lb-ft (Nm) ............... 21.7-28.9 (29.4-39.2)
Full Flow Filter Bracket Stud, lb-ft (Nm) ............... 21.7-25.3 (29.4-34.3)
Water Pump Base Frame Mounting Bolts, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Thermostat Housing Upper Cover Bolts, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Cooling Radiator Water Inlet Joint Pipe Bolt, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)
Cooling Fan Pulley Assembly Hub Lock Nut, lb-ft (Nm) ............... 32.5-39.7 (44.1-53.9)
Intake Manifold Base Engine Bolts, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Exhaust Manifold High Temperature Stud, lb-ft (Nm) ............... 18.8-23.1 (25.5-31.4)
Starter Motor Chassis Flange Bolts, lb-ft (Nm) ............... 32.5-36.2 (44.1-49.0)
Alternator Pivot Support Main Bolt, lb-ft (Nm) ............... 32.5-36.2 (44.1-49.0)
Alternator Adjustment Tension Lock Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Glow Plugs Main Core Hex Nuts, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Oil Pressure Switch Warning Sensor Assembly, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Coolant Temperature Thermo Switch Sensor, lb-ft (Nm) ............... 14.5-21.7 (19.6-29.4)
Gear Case Housing Front Face Cover Fasteners, lb-ft (Nm) ............... 17.3-21.7 (23.5-29.4)
Oil Strainer Suction Tube Support Bolt, lb-ft (Nm) ............... 7.2-10.8 (9.8-14.7)

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