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Isuzu 3KC1 Engine

The Isuzu 3KC1 is an in-line, water-cooled, 4-cycle, naturally aspirated industrial diesel engine. Engineered primarily for light industrial machinery, mini excavators, compact agricultural equipment, and generator sets, it is highly regarded by workshop technicians for its compact size, robust block construction, and reliable mechanical layout. It belongs to Isuzu's small-displacement multi-cylinder family and utilizes a conventional overhead camshaft layout combined with high-durability internal components designed for stable operation under high continuous loads.

The engine uses an Overhead Camshaft (OHC) design. A high-strength gear and chain drive system coordinates the timing drive assembly directly from the crankshaft. Each cylinder is serviced by two valves (one intake, one exhaust), which are adjusted via standard bucket or rocker-arm mechanical configurations common to Isuzu's industrial powerplants. Number of Cylinders: 3 cylinders in-line. Bore x Stroke: 74 mm x 76 mm. Total Piston Displacement: 980 cc (0.98 Liters).

The 3KC1 features an indirect injection (IDI) design utilizing a swirl-chamber configuration in the cylinder head for clean, complete diesel combustion. Fuel delivery is handled by a deck-mounted, mechanically driven in-line Bosch-type injection pump assembly. The fuel path consists of a low-pressure mechanical feed pump drawing fuel through a primary water-separator filter, pressurized lines traveling to individual nozzle holder assemblies, and high-pressure fuel injectors. Engine speed regulation is controlled by an integrated mechanical flyweight governor assembly attached directly to the injection pump rack.

The lubrication circuit is a full-pressure feed system powered by a trochoid-type or gear-driven oil pump. Engine oil is drawn through a pickup screen in the bottom oil pan, routed through a spin-on full-flow filtration canister, and distributed through internal oil galleries to the main crankshaft bearings, connecting rods, and overhead camshaft assembly. The system relies on precise oil relief valves to maintain stable oil pressure at high operating temperatures.

Engine temperature is regulated by a liquid-forced circulation system. A belt-driven centrifugal water pump forces coolant through the cylinder block and cylinder head water jackets. Flow path distribution is managed by a wax-pellet type inline thermostat that restricts flow to the radiator during warm-up and opens fully at normal operating limits to bypass coolant back into the primary heat exchanger or radiator loop.

General Technical Data

Engine Specifications

Engine Model ............... Isuzu 3KC1
Engine Type ............... 4-cycle inline 3-cylinder indirect injection liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line vertical
Engine Bore, in (mm) ............... 2.91 (74.0)
Engine Stroke, in (mm) ............... 2.99 (76.0)
Displacement, cu.in (L) ............... 59.8 (0.980)
Rated Engine Power, hp (kW) ............... 22.0-27.5 (16.4-20.5)
Rated Engine Speed, rpm ............... 2800-3000
Maximum No-Load Speed, rpm ............... 3150-3300
Minimum Idle Speed, rpm ............... 800-900
Peak Torque, lb-ft (Nm) ............... 42.7-47.2 (58.0-64.0) at 2000 rpm
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 23.0:1
Firing Order ............... 1-3-2
Direction of Rotation ............... Counter-clockwise viewed from flywheel side
Cylinder Block Type ............... Monoblock cast iron
Cylinder Head Type ............... Cast iron overhead valve
Combustion Chamber Type ............... Swirl chamber swirl jet design
Lubrication System ............... Forced full-pressure feed lubrication system
Oil Pump Type ............... Trochoid gear-driven type pump
Oil Filter Type ............... Full-flow cartridge spin-on paper element
Cooling System Type ............... Liquid-cooled forced circulation with radiator
Water Pump Type ............... Belt-driven centrifugal impeller type pump
Thermostat Type ............... Wax pellet type with bypass valve
Air Cleaner Type ............... Dry heavy duty dual-stage paper element filter
Starting System Type ............... Electric starter motor engagement
Electrical System Voltage, V ............... 12
Alternator Capacity, A ............... 20-35

Fuel System

Fuel Injection Pump Type ............... Bosch Type PFR inline Bosch Kiki mini pump
Fuel Feed Pump Type ............... Mechanical diaphragm type or electric external pump
Fuel Injection Nozzle Type ............... Throttle type nozzle design
Fuel Injection Nozzle Holder Type ............... Screw-in assembly holder design
Fuel Injection Pressure, psi (MPa) ............... 1991.0-2133.0 (13.73-14.71)
Fuel Injection Timing, deg BTDC ............... 19.0-21.0
Fuel Filter Type ............... Spin-on cartridge type with integrated water separator
Fuel Injection Tubing Outer Diameter, in (mm) ............... 0.236 (6.0)
Fuel Injection Tubing Inner Diameter, in (mm) ............... 0.078 (2.0)
Fuel Transfer Pump Minimum Pressure, psi (kPa) ............... 2.84-4.26 (19.6-29.4)
Fuel Feed Line Diameter, in (mm) ............... 0.315 (8.0)
Fuel Return Line Diameter, in (mm) ............... 0.236 (6.0)
Fuel Tank Venting Capacity, cfm (L/min) ............... 0.53 (15.0)
Governor Type ............... Mechanical centrifugal all-speed governor assembly
Injection Nozzle Needle Valve Diameter, in (mm) ............... 0.157 (4.0)
Injection Nozzle Pintle Diameter, in (mm) ............... 0.039 (1.0)
Fuel System Air Bleeding Type ............... Manual air bleed

Dimensions and Weight

Overall Length, in (mm) ............... 19.5 (495)
Overall Width, in (mm) ............... 17.5 (445)
Overall Height, in (mm) ............... 21.8 (555)
Dry Weight, lbs (kg) ............... 280 (128)
Wet Weight, lbs (kg) ............... 305 (138)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (MPa) ............... 441.0 (3.04)
Compression Pressure, Limit Minimum, psi (MPa) ............... 370.0 (2.55)
Maximum Pressure Between Cylinders, psi (MPa) ............... 28.4 (0.196)
Engine Oil Pressure at Rated Speed, psi (kPa) ............... 42.6-56.8 (294.0-392.0)
Engine Oil Pressure at Low Idle Speed, psi (kPa) ............... 14.2 (98.0)
Engine Oil Temperature Normal Range, F (C) ............... 176.0-212.0 (80.0-100.0)
Thermostat Opening Temperature, F (C) ............... 170.0 (76.5)
Thermostat Full Open Temperature, F (C) ............... 194.0 (90.0)
Drive Belt Deflection Under 22 lb Force, 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 ......................... CC or CD
Engine Oil Capacity with Filter, qt (L) ............... 4.23 (4.0)
Engine Oil Capacity without Filter, qt (L) ............... 3.70 (3.5)
Cooling System Fluid Capacity, qt (L) ............... 2.11 (2.0)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 400 hours
Valve clearance adjustment ............... Every 400 hours
Fuel system inspection ............... Every 600 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Bore Diameter, in (mm) ............... 2.9133-2.9145 (74.000-74.030)
Cylinder Bore Out-of-Roundness, in (mm) ............... 0.0004 (0.010)
Cylinder Bore Taper Dimension, in (mm) ............... 0.0004 (0.010)
Piston Skirt Outer Diameter, in (mm) ............... 2.9106-2.9118 (73.930-73.960)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0019-0.0035 (0.048-0.089)
Piston Pin Outside Diameter, in (mm) ............... 0.7872-0.7874 (19.995-20.000)
Piston Pin to Piston Pin Boss Clearance, in (mm) ............... 0.0001-0.0004 (0.002-0.010)
First Ring Groove Width, in (mm) ............... 0.0610-0.0622 (1.550-1.580)
Second Ring Groove Width, in (mm) ............... 0.0598-0.0610 (1.519-1.549)
Oil Ring Groove Width, in (mm) ............... 0.1582-0.1594 (4.018-4.048)
First Ring Side Clearance, in (mm) ............... 0.0023-0.0037 (0.058-0.094)
Second Ring Side Clearance, in (mm) ............... 0.0015-0.0029 (0.038-0.074)
Oil Ring Side Clearance, in (mm) ............... 0.0007-0.0021 (0.018-0.053)
First Ring End Gap, in (mm) ............... 0.0078-0.0137 (0.198-0.348)
Second Ring End Gap, in (mm) ............... 0.0078-0.0137 (0.198-0.348)
Oil Ring End Gap, in (mm) ............... 0.0078-0.0137 (0.198-0.348)
Connecting Rod Small End Bushing ID, in (mm) ............... 0.7876-0.7881 (20.005-20.018)
Piston Pin to Small End Bushing Clearance, in (mm) ............... 0.0002-0.0009 (0.005-0.023)
Crankshaft Main Journal Diameter, in (mm) ............... 1.9665-1.9673 (49.949-49.969)
Crankshaft Rod Journal Diameter, in (mm) ............... 1.5732-1.5740 (39.959-39.980)
Crankshaft Main Journal Oil Clearance, in (mm) ............... 0.0013-0.0029 (0.033-0.074)
Crankshaft Rod Journal Oil Clearance, in (mm) ............... 0.0011-0.0027 (0.028-0.069)
Crankshaft End Play, in (mm) ............... 0.0023-0.0094 (0.058-0.239)
Cylinder Head Lower Surface Flatness Distortion, in (mm) ............... Under 0.0019 (0.048)
Valve Stem Outside Diameter (Intake), in (mm) ............... 0.2736-0.2742 (6.949-6.965)
Valve Stem Outside Diameter (Exhaust), in (mm) ............... 0.2724-0.2732 (6.919-6.939)
Valve Guide Inside Diameter, in (mm) ............... 0.2755-0.2761 (7.000-7.013)
Valve Stem to Valve Guide Oil Clearance (Intake), in (mm) ............... 0.0013-0.0025 (0.033-0.064)
Valve Stem to Valve Guide Oil Clearance (Exhaust), in (mm) ............... 0.0023-0.0037 (0.058-0.094)
Valve Guide Projection Height Above Head Top Surface, in (mm) ............... 0.452-0.492 (11.5-12.5)
Valve Spring Free Length (Standard), in (mm) ............... 1.488 (37.8)
Valve Spring Free Length (Wear Limit), in (mm) ............... 1.429 (36.3)
Camshaft Journal Outside Diameter (Front), in (mm) ............... 1.5724-1.5732 (39.939-39.959)
Camshaft Journal Outside Diameter (Center), in (mm) ............... 1.5330-1.5338 (38.938-38.958)
Camshaft Journal Outside Diameter (Rear), in (mm) ............... 1.4937-1.4944 (37.940-37.958)
Camshaft Bearing Oil Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.089)
Cam Lobe Height (Intake), in (mm) ............... 1.3015-1.3031 (33.058-33.099)
Cam Lobe Height (Exhaust), in (mm) ............... 1.3015-1.3031 (33.058-33.099)
Camshaft End Play, in (mm) ............... 0.0019-0.0059 (0.048-0.150)
Rocker Arm Shaft Outside Diameter, in (mm) ............... 0.5893-0.5900 (14.968-14.986)
Rocker Arm Bushing Inside Diameter, in (mm) ............... 0.5905-0.5913 (15.000-15.020)
Rocker Arm to Shaft Radial Oil Clearance, in (mm) ............... 0.0005-0.0020 (0.013-0.051)
Tappet Installation Bore Inside Diameter, in (mm) ............... 0.8267-0.8275 (21.000-21.018)
Tappet to Cylinder Block Guide Clearance, in (mm) ............... 0.0008-0.0022 (0.020-0.056)
Crankshaft Timing Gear Inside Diameter Bore, in (mm) ............... 1.3779-1.3787 (35.000-35.020)
Camshaft Timing Gear Inside Diameter Bore, in (mm) ............... 1.1811-1.1819 (30.000-30.021)

Tightening Torques

Cylinder Head Bolt (1-Stage), lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Cylinder Head Bolt (2-Stage), lb-ft (Nm) ............... 47.0-54.2 (63.7-73.5)
Cylinder Head Bolt (3-Stage), lb-ft (Nm) ............... 68.7-75.9 (93.1-102.9)
Connecting Rod Bearing Cap Nut, lb-ft (Nm) ............... 21.7-28.9 (29.4-39.2)
Main Bearing Cap Bolt, lb-ft (Nm) ............... 39.8-47.0 (53.9-63.7)
Flywheel Assembly Retention Bolt, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Crankshaft Front Pulley Snout Bolt, lb-ft (Nm) ............... 61.5-68.7 (83.3-93.1)
Camshaft Thrust Plate Assembly Bolt, lb-ft (Nm) ............... 13.0-17.3 (17.6-23.5)
Camshaft Timing Gear Central Drive Bolt, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Idler Gear Support Shaft Assembly Bolt, lb-ft (Nm) ............... 17.3-24.6 (23.5-33.3)
Rocker Arm Shaft Stanchion Support Bolt, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Valve Cover Bonnet Seal Seating Nut, lb-ft (Nm) ............... 5.8-8.7 (7.8-11.8)
Oil Pan Sump Perimeter Attachment Bolt, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Oil Pan Sump Fluid Drain Plug, lb-ft (Nm) ............... 36.1-43.4 (49.0-58.8)
Timing Chain Gear Front Cover Plate Bolt, lb-ft (Nm) ............... 13.0-17.3 (17.6-23.5)
Flywheel Housing Backing Bolt, lb-ft (Nm) ............... 39.8-47.0 (53.9-63.7)
Fuel Injection Pump Deck Shifting Nut, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Fuel Injection Nozzle Injector, lb-ft (Nm) ............... 36.1-43.4 (49.0-58.8)
Fuel Injection High Pressure Nut, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Fuel Overflow Return Banjo Joint Bleed Pipe Screw, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Glow Plug Terminal Body Insertion Cylinder Head, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Glow Plug Top Electric Connection Rib Wire Nut, lb-ft (Nm) ............... 1.4-2.2 (1.9-3.0)
Oil Pump Internal Assembly Inner Backplate Bolt, lb-ft (Nm) ............... 5.8-8.7 (7.8-11.8)
Water Pump Assembly Body, lb-ft (Nm) ............... 13.0-17.3 (17.6-23.5)
Cooling Fan Blade Center Hub Nut, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Thermostat Housing Water Outlet Flange Bolt, lb-ft (Nm) ............... 13.0-17.3 (17.6-23.5)
Intake Air Inlet Manifold Cast Assembly Bolt, lb-ft (Nm) ............... 13.0-17.3 (17.6-23.5)
Exhaust Gas Outlet Manifold Cast Assembly Nut, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Starter Motor Electrical Flange Mount Bolt, lb-ft (Nm) ............... 39.8-47.0 (53.9-63.7)
Alternator Charging Unit Tension Arm Bracket Bolt, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Alternator Charging Unit Base Main Frame Bolt, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Oil Pressure Switch Indicator Sensor Signal Body, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Water Temperature Gauge Sender Sensor, lb-ft (Nm) ............... 14.5-21.7 (19.6-29.4)
Fuel Filter Mounting Bracket Chassis Frame Bolt, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Air Cleaner Filter Housing Support Mount Bolt, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Exhaust Shield Guard Heat Deflector Screws, lb-ft (Nm) ............... 3.0-4.3 (4.1-5.8)
Front Oil Seal Retainer Backing Cover Bolt, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Injection Pump Automatic Central Hex Head Nut, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Governor Housing Cover Plate Sealing Screw, lb-ft (Nm) ............... 3.0-4.3 (4.1-5.8)
Fuel Feed Supply Transfer Pump Mounting Nut, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)
Oil Strainer Intake Tube Support Bracket Bolt, lb-ft (Nm) ............... 7.2-10.1 (9.8-13.7)

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• Isuzu Engines Specs
  
• Isuzu 3KC2 Specs
  
• Isuzu 3KR1 Specs
  
• Isuzu 3KR2 Specs
  
• Isuzu 3LB1 Specs
  
• Isuzu 3LD1 Specs
  
• Isuzu 3LD2 Specs
  

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