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Isuzu 3KC2 Engine

The Isuzu 3KC2 is a compact, liquid-cooled, 3-cylinder, 4-stroke industrial diesel engine belonging to Isuzu's K-series engine lineup. Engineered primarily for light construction equipment, agricultural machinery, and heavy industrial applications, it is commonly utilized in machinery like mini-excavators (Hitachi EX30, Hanix SB20), air compressors ( Airman PDS90S), and forklifts. Characterized by a cast-iron block design and an overhead valve layout, the engine is valued for its mechanical simplicity, exceptional thermal efficiency, high power-to-weight ratio, and long-term durability under low-to-medium continuous load conditions.

The engine utilizes a conventional OHV (Overhead Valve) configuration featuring a gear-driven camshaft mounted within the cylinder block. Power is transferred to the valve train through heavy-duty pushrods and rocker arms, managing two valves per cylinder (one intake and one exhaust) for a total of six valves across the engine block. Cylinder structure specifications feature a standard cylinder bore of 74.0 mm (2.91 inches). The stroke measures 76.0 mm, tracking the physical framework configuration shared with the baseline 3KC1 engine architecture to deliver a total displacement of 0.98 liters (980 cc).

The engine utilizes a mechanical, indirect-injection fuel distribution system. Fuel delivery is controlled by a high-pressure, multi-plunger in-line fuel injection pump coupled with a mechanical governor that automatically adjusts throttle delivery based on operational engine load. High-pressure steel lines route the metered diesel fuel directly to individual fuel injectors, which atomize the fuel into the pre-combustion chambers. The firing order for the 3-cylinder assembly is 1-3-2, and electric glow plugs are embedded in the cylinder head to preheat the combustion zones for reliable cold weather starting.

Engine lubrication is driven by a high-efficiency, gear-type oil pump that establishes a full pressure-fed system. Motor oil is drawn up from the deep-stamped oil pan, forced through a full-flow replaceable spin-on oil filter element, and routed through internal oil galleries to lubricate main bearings, connecting rod journals, camshaft lobes, and the upper rocker arm assembly. An oil pressure sensor warns operators of critical pressure drops before damage occurs.

Thermal regulation is maintained via a heavy-duty, forced-circulation liquid-cooling system. A belt-driven centrifugal water pump continuously circulates coolant through the engine block water jackets and the cylinder head channels. System operational temperatures are monitored by an integrated cooling thermostat that regulates flow to an external radiator. An engine-driven cooling fan blade draws air across the radiator matrix to optimize heat dissipation during high-ambient operation.

General Technical Data

Engine Specifications

Engine Model ............... Isuzu 3KC2
Engine Type ............... 4-cycle inline 3-cylinder overhead valve liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 2.91 (74.0)
Engine Stroke, in (mm) ............... 2.99 (76.0)
Displacement, cu.in (L) ............... 59.8 (0.98)
Rated Engine Power, hp (kW) ............... 22.0-24.0 (16.4-17.9)
Rated Engine Speed, rpm ............... 3000
Maximum Engine Power, hp (kW) ............... 26.0 (19.4)
Peak Torque ............... 42.6 Nm (31.4 lb-ft) at 2000 rpm
High Idle Speed, rpm ............... 3200-3300
Low Idle Speed, rpm ............... 900-1000
Aspiration Type ............... Naturally Aspirated
Operating Speed Range, rpm ............... 1500-3000
Compression Ratio ............... 23.0:1
Firing Order ............... 1-3-2
Direction of Rotation ............... Counterclockwise looking at flywheel
Cylinder Block Type ............... Cast iron mono-block structure
Cylinder Head Type ............... Cast iron single piece structure
Combustion Chamber Design ............... Swirl chamber type or indirect injection
Lubrication System ............... Forced pressure feed configuration
Oil Pump Type ............... Trochoid type gear driven mechanical assembly
Oil Filter Type ............... Full-flow cartridge spin-on paper element unit
Cooling System ............... Pressurized liquid-cooled circulation setup
Water Pump Type ............... Belt-driven centrifugal impeller model
Thermostat Type ............... Wax pellet type automatic temperature regulator
Air Cleaner Type ............... Dry heavy duty dual-stage element housing
Starting System ............... Electric starter motor actuation
Electrical System Voltage, V ............... 12
Alternator Output Capacity, A ............... 20-35

Fuel System

Injection Pump Model ............... Bosch Type PFR inline mini pump unit
Injection Pump Drive Mechanism ............... Camshaft lobe mechanical actuation
Governor Mechanism Type ............... Mechanical centrifugal mechanical flyweight type
Fuel Feed Pump Type ............... Mechanical diaphragm style lift unit
Injection Nozzle Type ............... Throttle type needle injector valve
Injection Nozzle Holder Model ............... Bosch Type KCA component structure
Nozzle Opening Pressure, psi (kPa) ............... 1849-1991 (12750-13730)
Fuel Injection Timing, deg BTDC ............... 18-20
Fuel Filter Construction ............... Cartridge spin-on paper element assembly
Maximum Fuel Return Flow Rate, gph (L/h) ............... 1.58 (6.0)
Fuel Transfer Pump Pressure, psi (kPa) ............... 2.84-4.26 (19.6-29.4)
Injection Pipe Inner Diameter, in (mm) ............... 0.059 (1.5)
Injection Pipe Outer Diameter, in (mm) ............... 0.236 (6.0)
Fuel Main Line Diameter, in (mm) ............... 0.315 (8.0)
Fuel Return Line Diameter, in (mm) ............... 0.236 (6.0)

Dimensions and Weight

Overall Length, in (mm) ............... 20.3 (515)
Overall Width, in (mm) ............... 17.5 (445)
Overall Height, in (mm) ............... 21.6 (550)
Dry Weight, lbs (kg) ............... 200 (90)
Wet Weight, lbs (kg) ............... 215 (98)

Maintenance Data

Service Information

Compression Pressure, psi (kPa) ............... 441 (3040)
Minimum Compression Pressure, psi (kPa) ............... 370 (2550)
Maximum Cylinder Pressure Variance, psi (kPa) ............... 28.4 (196)
Minimum Oil Pressure at Idle, psi (kPa) ............... 14.2 (98.0)
Normal Operating Oil Pressure, psi (kPa) ............... 42.6-56.8 (294.0-392.0)
Thermostat Opening Temperature, F (C) ............... 170 (76.5)
Thermostat Full Open Temperature, F (C) ............... 194 (90.0)
Fan Belt Deflection Standard, in (mm) ............... 0.39-0.47 (10.0-12.0)
Intake Valve Clearance, in (mm) ............... 0.0098 (0.25)
Exhaust Valve Clearance, in (mm) ............... 0.0098 (0.25)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30 or SAE 15W-40
API Service Classifications ......................... CD or CE
Engine Oil Capacity, qt (L) ............... 3.17-3.70 (3.0-3.5)
Cooling System Capacity, qt (L) ............... 4.22 (4.0)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 250 hours
Valve clearance adjustment ............... Every 500 hours
Fuel system inspection ............... Every 500 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Bore Inner Diameter (Std), in (mm) ............... 2.9133-2.9145 (74.000-74.030)
Cylinder Bore Out-of-Round (Service Limit), in (mm) ............... 0.0007 (0.020)
Cylinder Bore Taper (Max Limit), in (mm) ............... 0.0007 (0.020)
Crankshaft Crankpin Journal O.D., in (mm) ............... 1.5736-1.5748 (39.970-40.000)
Crankshaft Runout Maximum Value, in (mm) ............... 0.0011 (0.030)
Crankshaft End Play, in (mm) ............... 0.0023-0.0055 (0.060-0.140)
Main Bearing Oil Clearance, in (mm) ............... 0.0013-0.0029 (0.034-0.075)
Connecting Rod Small End Bushing ID, in (mm) ............... 0.8669-0.8677 (22.020-22.040)
Connecting Rod Bearing Oil Clearance, in (mm) ............... 0.0013-0.0027 (0.034-0.070)
Connecting Rod Side Play, in (mm) ............... 0.0059-0.0098 (0.150-0.250)
Crankshaft Main Journal O.D., in (mm) ............... 1.9673-1.9685 (49.970-50.000)
Piston Pin to Connecting Rod Bushing Clearance, in (mm) ............... 0.0007-0.0019 (0.020-0.050)
Piston Outside Diameter, in (mm) ............... 2.9106-2.9118 (73.930-73.960)
Piston-to-Cylinder Wall Clearance, in (mm) ............... 0.0023-0.0031 (0.060-0.080)
Piston Pin Bore Inner Diameter, in (mm) ............... 0.8661-0.8665 (22.000-22.010)
Piston Pin Outside Diameter, in (mm) ............... 0.8657-0.8661 (21.990-22.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0000-0.0007 (0.002-0.020)
Top Ring Groove Clearance, in (mm) ............... 0.0023-0.0039 (0.060-0.100)
Second Ring Groove Clearance, in (mm) ............... 0.0019-0.0035 (0.050-0.090)
Oil Ring Groove Clearance, in (mm) ............... 0.0011-0.0027 (0.030-0.070)
Top Ring End Gap, in (mm) ............... 0.0078-0.0137 (0.200-0.350)
Second Ring End Gap, in (mm) ............... 0.0059-0.0118 (0.150-0.300)
Oil Ring End Gap, in (mm) ............... 0.0078-0.0157 (0.200-0.400)
Cylinder Head Lower Surface Flatness, in (mm) ............... 0.0019 (0.050)
Valve Stem Outside Diameter (Intake), in (mm) ............... 0.2736-0.2742 (6.950-6.965)
Valve Stem Outside Diameter (Exhaust), in (mm) ............... 0.2724-0.2732 (6.920-6.940)
Valve Guide to Valve Stem Clearance (Intake), in (mm) ............... 0.0013-0.0025 (0.035-0.065)
Valve Guide to Valve Stem Clearance (Exhaust), in (mm) ............... 0.0021-0.0033 (0.055-0.085)
Valve Guide Inner Diameter, in (mm) ............... 0.2755-0.2761 (7.000-7.015)
Valve Spring Free Length (Standard), in (mm) ............... 1.5314 (38.900)
Valve Spring Free Length (Wear Limit), in (mm) ............... 1.4724 (37.400)
Valve Seat Contact Width, in (mm) ............... 0.0472-0.0590 (1.200-1.500)
Camshaft Journal Outside Diameter (Front), in (mm) ............... 1.5732-1.5744 (39.960-39.990)
Camshaft Journal Outside Diameter (Middle), in (mm) ............... 1.5338-1.5350 (38.960-38.990)
Camshaft Journal Outside Diameter (Rear), in (mm) ............... 1.4944-1.4956 (37.960-37.990)
Camshaft Bearing Oil Clearance, in (mm) ............... 0.0007-0.0027 (0.020-0.070)
Cam Lobe Height (Intake), in (mm) ............... 1.3051 (33.150)
Cam Lobe Height (Exhaust), in (mm) ............... 1.3051 (33.150)
Rocker Arm Shaft Outside Diameter, in (mm) ............... 0.4716-0.4724 (11.980-12.000)
Rocker Arm Bushing Inside Diameter, in (mm) ............... 0.4728-0.4740 (12.010-12.040)
Rocker Arm to Shaft Clearance, in (mm) ............... 0.0003-0.0023 (0.010-0.060)
Tappet Outside Diameter Standard, in (mm) ............... 0.8251-0.8259 (20.960-20.980)
Cylinder Block Tappet Bore Inner Diameter, in (mm) ............... 0.8267-0.8275 (21.000-21.021)
Tappet to Cylinder Block Bore Clearance, in (mm) ............... 0.0007-0.0024 (0.020-0.061)
Idler Gear Shaft Outside Diameter, in (mm) ............... 1.1803-1.1811 (29.980-30.000)
Idler Gear Bushing Inside Diameter, in (mm) ............... 1.1818-1.1830 (30.020-30.050)
Idler Gear Bushing to Shaft Clearance, in (mm) ............... 0.0007-0.0027 (0.020-0.070)

Tightening Torques

Cylinder Head Bolt (Step One), lb-ft (Nm) ............... 21.6 (29.4)
Cylinder Head Bolts (Step Two), lb-ft (Nm) ............... 43.3 (58.8)
Cylinder Head Bolts (Final), lb-ft (Nm) ............... 54.2-61.4 (73.5-83.3)
Connecting Rod Bearing Cap Bolts, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 39.7-46.9 (53.9-63.7)
Flywheel Retaining Bolts, lb-ft (Nm) ............... 43.3-50.6 (58.8-68.6)
Crankshaft Pulley Center Bolt, lb-ft (Nm) ............... 65.0-72.3 (88.2-98.0)
Camshaft Timing Gear Retaining Bolt, lb-ft (Nm) ............... 43.3-50.6 (58.8-68.6)
Idler Gear Shaft Retaining Bolt, lb-ft (Nm) ............... 17.3-21.6 (23.5-29.4)
Rocker Arm Shaft Bracket Bolts, lb-ft (Nm) ............... 15.9-20.2 (21.6-27.4)
Cylinder Head Rocker Cover Cap Nuts, lb-ft (Nm) ............... 5.8-8.7 (7.8-11.8)
Oil Pan Drain Plug, lb-ft (Nm) ............... 36.1-43.3 (49.0-58.8)
Oil Pan Mounting Perimeter Bolts, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Timing Gear Case Cover Bolts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Flywheel Housing to Block Bolts, lb-ft (Nm) ............... 36.1-43.3 (49.0-58.8)
Fuel Injection Pump Delivery Valve Holders, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Fuel Injection Pump Locking Fixing Nuts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Fuel Injection Nozzle Holder Assembly to Head, lb-ft (Nm) ............... 43.3-50.6 (58.8-68.6)
Fuel Injection Nozzle Retaining Cap Nut, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Fuel High Pressure Line Flare Gland Nuts, lb-ft (Nm) ............... 18.0-21.6 (24.5-29.4)
Fuel Return Line Leakage Pipe Nut, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Glow Plug Terminal Small Hex Nuts, lb-ft (Nm) ............... 1.4-2.1 (2.0-3.0)
Glow Plug Body, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Oil Pressure Sensor Switch, lb-ft (Nm) ............... 10.1-14.5 (13.7-19.6)
Coolant Temperature Sensor Switch, lb-ft (Nm) ............... 14.5-21.6 (19.6-29.4)
Water Pump Assembly Mounting Bolts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Cooling Fan Blade Fitting Retaining Screws, lb-ft (Nm) ............... 5.8-8.7 (7.8-11.8)
Thermostat Housing Cap Bolts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Intake Manifold Securing Hex Bolts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Exhaust Manifold Heat Shield Securing Nuts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Starter Motor Frame Mounting Hex Flange Bolts, lb-ft (Nm) ............... 54.2-65.0 (73.5-88.2)
Alternator Pivot Mount Bracket Long Bolt, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Alternator Adjuster Link Lock Bolts, lb-ft (Nm) ............... 14.5-18.8 (19.6-25.5)
Oil Pump Strainer Pickup Tube Support Screw, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)

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• Isuzu Engines Specs
  
• Isuzu 3KC1 Specs
  
• Isuzu 3KR1 Specs
  
• Isuzu 3KR2 Specs
  
• Isuzu 3LB1 Specs
  
• Isuzu 3LD1 Specs
  
• Isuzu 3LD2 Specs
  

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