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Isuzu 3CH1 Engine

The Isuzu 3CH1 is an industrial, vertical in-line, 3-cylinder, 4-stroke diesel engine belonging to Isuzu's C-Series lineup. Designed primarily for stationary equipment, marine applications, and compact construction machinery, this compact unit features a naturally aspirated induction system. It relies on an indirect injection (IDI) design with a ball-type swirl combustion chamber. Engineered to comply with stringent environmental guidelines, it satisfies U.S. EPA Final Tier 4 and EU Stage V emissions standards. Its robust mechanical blueprint includes a rigid block assembly and a heavy-duty high-angularity oil pan, which minimizes starvation risk under steep operational angles.

Valvetrain System: Overhead Valve (OHV) pushrod-driven architecture. Actuation: Single camshaft mounted in the cylinder block actuating mechanical rocker arm assemblies. Two valves per cylinder (one intake, one exhaust) featuring increased intake and exhaust valve profiles for enhanced gas exchange efficiency. Bore (Cylinder Diameter): 80 mm (3.15 inches). Stroke (Piston Travel): 84 mm (3.31 inches). Total Displacement: 1.266 Liters (77.25 cubic inches).

Fuel System Description: Indirect injection (IDI) design utilizing an advanced ball-type swirl combustion chamber to mix fuel and compressed air. Delivery Pump: Mechanical inline fuel injection pump calibrated for linear fuel delivery relative to engine timing requirements. Feed Pump: Equipped with a 12-volt electronic self-priming fuel lift pump that manages line priming and prevents vapor lock. Starting Aid: Integrated high-draw 12V glow plug grid fitted into the pre-combustion chamber to secure reliable ignition during cold-crank sequences.

Lubrication System Type: Forced pressure feed system driven by a high-efficiency trochoid oil pump. Sump Design: Equipped with a specialized high-angularity oil pan optimized for consistent pick-up at operating angles up to 20 deg constant or 30 deg intermittent. Filtration: Full-flow, spin-on cartridge filtration element accompanied by an integrated internal bypass valve.

Cooling System Type: Liquid-cooled, closed-circuit configuration featuring forced circulation. Circulation: Centrifugal water pump driven via an auxiliary V-belt assembly off the crankshaft pulley. Thermal Control: Bypass-type thermostat regulator designed to accurately manage engine block temperatures under fluctuating loads. Chemical Chemistry: Formulated to utilize Organic Acid Technology (O.A.T.) extended-life coolants.

General Technical Data

Engine Specifications

Engine Model ............... Isuzu 3CH1
Engine Type ............... 4-cycle inline 3-cylinder indirect injection liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.15 (80.0)
Engine Stroke, in (mm) ............... 3.31 (84.0)
Displacement, cu.in (L) ............... 77.3 (1.267)
Rated Engine Power at Variable Speed, hp (kW) ............... 23.9 (17.8)
Rated Engine Power at Constant Speed, hp (kW) ............... 14.9 (11.1)
Minimum Operating Power, hp (kW) ............... 14.8 (11.0)
Maximum Operating Power, hp (kW) ............... 23.9 (17.8)
Rated Engine Speed, rpm ............... 1800-3000
Peak Torque, lb-ft (Nm) ............... 45.1 (61.2) at 2000 rpm
Minimum Peak Torque, lb-ft (Nm) ............... 36.5 (49.5)
Low Idle Speed, rpm ............... 900-1000
High Idle Speed, rpm ............... 3150-3250
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 23.0:1
Firing Order ............... 1-3-2
Cylinder Rotation Direction ............... Counterclockwise viewed from flywheel
Combustion Chamber Type ............... Swirl chamber indirect injection
Cylinder Block Type ............... Cast iron monoblock
Cylinder Head Type ............... Cast iron overhead valve
Valves per Cylinder ............... 2
Valve Train Layout ............... OHV actuated by pushrods and lifters
Lubrication System ............... Full-pressure feed
Oil Pump Type ............... Trochoid gear-driven
Oil Filter Type ............... Full-flow cartridge spin-on
Cooling System ............... Forced liquid-cooled circulation
Water Pump Type ............... Belt-driven centrifugal pump
Cooling Fan Type ............... Suction or pusher plastic fan
Air Cleaner Type ............... Dry element dual-stage filter
Starting System ............... Electric starter motor
Electrical System Voltage, V ............... 12V
Alternator Amperage Output, A ............... 40.0
Alternator Amperage Output (Optional), A ............... 60.0

Fuel System

Fuel Injection Pump Type ............... Bosch PFR mini in-line cassette pump
Injection Pump Control ............... Mechanical rack and pinion linkage
Fuel Feed Pump Type ............... Electronic self-priming electromagnetic lift pump
Fuel Feed Pump Operating Pressure, psi (bar) ............... 3.63-5.07 (0.25-0.35)
Fuel Feed Pump Maximum Flow Rate, gph (L/h) ............... 11.9 (45.0)
Fuel Injection Nozzle Type ............... Throttle type pintle nozzle
Fuel Injection Nozzle Holder ............... Flange or screw-in mounting design
Governor Type ............... Mechanical centrifugal type
Nozzle Injection Opening Pressure, psi (bar) ............... 1991-2132 (137.3-147.1)
Nozzle Rebuild Limit Pressure, psi (bar) ............... 1849 (127.5)
Fuel Injection Timing, deg BTDC ............... 14.0-16.0
Fuel Injection Advance Mechanism ............... Fixed mechanical shim adjustment
Fuel Filter Type ............... High-efficiency spin-on paper element with water separator
Maximum Fuel Return Flow Rate, gph (L/h) ............... 7.92 (30.0)
Maximum Fuel System Restriction, in Hg (kPa) ............... 4.02 (13.6)
Injection Line Outer Diameter, in (mm) ............... 0.236 (6.0)
Injection Line Inner Diameter, in (mm) ............... 0.078 (2.0)
Leak-off Pipe Diameter, in (mm) ............... 0.157 (4.0)

Dimensions and Weight

Overall Length, in (mm) ............... 22.4 (570)
Overall Width, in (mm) ............... 17.2 (435)
Overall Height, in (mm) ............... 23.1 (585)
Dry Weight Basic Configuration, lbs (kg) ............... 285 (130)
Dry Weight Open Power Unit Configuration, lbs (kg) ............... 350 (158)
Wet Weight with Fluids, lbs (kg) ............... 375 (170)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (bar) ............... 441.0 (30.4)
Compression Pressure, Limit Minimum, psi (bar) ............... 341.0 (23.5)
Compression Pressure Between Cylinders, psi (bar) ............... 28.4 (2.0)
Oil Pressure at Rated Speed, psi (bar) ............... 42.6-56.8 (3.0-4.0)
Oil Pressure at Low Idle Speed, psi (bar) ............... 14.2 (1.0)
Oil Pressure Relief Valve Regulating Pressure, psi (bar) ............... 63.9 (4.5)
Thermostat Initial Opening Temperature, F (C) ............... 170 (77)
Thermostat Full Open Temperature, F (C) ............... 194 (90)
Alternator Drive Belt Tension Deflection, in (mm) ............... 0.31-0.47 (8.0-12.0)
Intake Valve Clearance, in (mm) ............... 0.0079 (0.20)
Exhaust Valve Clearance, in (mm) ............... 0.0079 (0.20)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30 or SAE 15W-40
API Service Classifications ......................... CJ-4 or CK-4
Engine Oil Capacity, Pan Max Level, qt (L) ............... 7.08 (6.7)
Engine Oil Capacity, Pan Min Level, qt (L) ............... 5.28 (5.0)
Coolant Capacity, Engine Block Only, qt (L) ............... 2.11 (2.0)
Coolant Capacity with Radiator, qt (L) ............... 5.81 (5.5)

Service Intervals

Change oil and filter ............... Every 250 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 1000 hours
Replace fuel filter ............... Every 500 hours
Valve clearance adjustment ............... Every 1000 hours
Fuel system inspection ............... Every 1500 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 1000 hours
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Block Top Surface Flatness, in (mm) ............... 0.0020 (0.05)
Cylinder Block Tappet Bore ID, in (mm) ............... 0.8661-0.8669 (22.000-22.021)
Cylinder Bore Inside Diameter (Grade A), in (mm) ............... 3.1496-3.1500 (80.000-80.010)
Cylinder Bore Inside Diameter (Grade B), in (mm) ............... 3.1500-3.1504 (80.011-80.020)
Connecting Rod Big End Bore Inside Diameter, in (mm) ............... 2.0472-2.0478 (52.000-52.015)
Connecting Rod Crankpin Bearing Clearance, in (mm) ............... 0.0013-0.0029 (0.033-0.074)
Connecting Rod Big End Side Clearance, in (mm) ............... 0.0059-0.0118 (0.15-0.30)
Crankshaft Main Journal Outside Diameter, in (mm) ............... 2.1643-2.1650 (54.972-54.990)
Crankshaft Crankpin Journal Outside Diameter, in (mm) ............... 1.9280-1.9287 (48.972-48.990)
Crankshaft Main Bearing Oil Clearance, in (mm) ............... 0.0013-0.0030 (0.034-0.077)
Crankshaft Free End Play, in (mm) ............... 0.0023-0.0070 (0.060-0.180)
Piston Outside Diameter (Grade A), in (mm) ............... 3.1468-3.1472 (79.930-79.940)
Piston Outside Diameter (Grade B), in (mm) ............... 3.1472-3.1476 (79.941-79.950)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0023-0.0031 (0.06-0.08)
Top Ring Groove Width, in (mm) ............... 0.0807-0.0815 (2.05-2.07)
Second Ring Groove Width, in (mm) ............... 0.0610-0.0618 (1.55-1.57)
Oil Ring Groove Width, in (mm) ............... 0.1193-0.1201 (3.03-3.05)
Top Ring Side Clearance, in (mm) ............... 0.0023-0.0039 (0.06-0.10)
Second Ring Side Clearance, in (mm) ............... 0.0019-0.0035 (0.05-0.09)
Oil Ring Side Clearance, in (mm) ............... 0.0011-0.0027 (0.03-0.07)
Top Ring End Gap, in (mm) ............... 0.0079-0.0137 (0.20-0.35)
Second Ring End Gap, in (mm) ............... 0.0079-0.0137 (0.20-0.35)
Oil Ring End Gap, in (mm) ............... 0.0079-0.0157 (0.20-0.40)
Piston Pin Outside Diameter, in (mm) ............... 0.9841-0.9844 (24.995-25.000)
Piston Pin Bushing Inside Diameter, in (mm) ............... 0.9846-0.9852 (25.008-25.022)
Piston Pin to Piston Pin Bushing Clearance, in (mm) ............... 0.0003-0.0010 (0.008-0.027)
Piston Pin Hole Inside Diameter in Piston, in (mm) ............... 0.9842-0.9846 (24.998-25.008)
Cylinder Head Bottom Surface Distortion Flatness, in (mm) ............... 0.0020 (0.05)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.2736-0.2742 (6.950-6.965)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.2724-0.2732 (6.920-6.940)
Valve Guide Inside Diameter, in (mm) ............... 0.2755-0.2763 (7.000-7.018)
Intake Valve Stem to Valve Guide Clearance, in (mm) ............... 0.0013-0.0026 (0.035-0.068)
Exhaust Valve Stem to Valve Guide Clearance, in (mm) ............... 0.0023-0.0038 (0.060-0.098)
Valve Guide Projection Above Cylinder Head Top Face, in (mm) ............... 0.4527-0.4921 (11.5-12.5)
Valve Face Angle (Intake and Exhaust), deg ............... 45
Valve Seat Angle (Intake and Exhaust), deg ............... 45
Valve Spring Free Length (Standard), in (mm) ............... 1.6377 (41.60)
Valve Spring Free Length (Wear Limit), in (mm) ............... 1.5748 (40.00)
Camshaft Journal Outside Diameter, in (mm) ............... 1.5732-1.5740 (39.960-39.980)
Camshaft Journal Oil Clearance, in (mm) ............... 0.0007-0.0031 (0.020-0.080)
Cam Lobe Height (Intake), in (mm) ............... 1.3417-1.3448 (34.080-34.160)
Cam Lobe Height (Exhaust), in (mm) ............... 1.3417-1.3448 (34.080-34.160)
Camshaft Free End Play, in (mm) ............... 0.0019-0.0059 (0.050-0.150)
Rocker Arm Shaft Outside Diameter, in (mm) ............... 0.4716-0.4722 (11.982-11.995)
Rocker Arm Bushing Inside Diameter, in (mm) ............... 0.4724-0.4731 (12.000-12.018)
Rocker Arm to Shaft Clearance, in (mm) ............... 0.0002-0.0014 (0.005-0.036)

Tightening Torques

Cylinder Head Bolts (Initial Pass), lb-ft (Nm) ............... 22 lb-ft (30 Nm)
Cylinder Head Bolts (Second Pass), lb-ft (Nm) ............... 44 lb-ft (60 Nm)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 37-41 lb-ft (50-55 Nm)
Connecting Rod Cap Nut, lb-ft (Nm) ............... 24-28 lb-ft (32-38 Nm)
Flywheel Retaining Bolts, lb-ft (Nm) ............... 61-66 lb-ft (83-90 Nm)
Rocker Arm Shaft Support Bracket Bolts (M8), lb-ft (Nm) ............... 16.6-21.0 (22.6-28.4)
Cylinder Head Top Valve Cover Cap Nuts (M6), lb-ft (Nm) ............... 7.2-8.7 (9.8-11.8)
Flywheel Housing to Cylinder Block Bolts (M10), lb-ft (Nm) ............... 33.0-43.0 (45.0-58.0)
Oil Pan Bottom Drain Plug Fastener Screw, lb-ft (Nm) ............... 29.5-36.0
Oil Pump Assembly Body Bolts (M8), lb-ft (Nm) ............... 16.6-21.0 (22.6-28.4)
Fuel Injection Pump Drive Gear Nut, lb-ft (Nm) ............... 29.5-36.0 (40.0-49.0)
Fuel High Pressure Line Union Nut, lb-ft (Nm) ............... 18.0-22.0 (24.5-30.0)
Coolant Water Temperature Sensor Switch, lb-ft (Nm) ............... 14.5-22.0 (20.0-30.0)
Oil Pressure Switch Sensor, lb-ft (Nm) ............... 11.0-14.5 (15.0-20.0)
Exhaust Manifold Structural Retaining Nut (M8), lb-ft (Nm) ............... 16.6-21.0 (22.6-28.4)
Intake Manifold Face Plate Retaining Bolts (M8), lb-ft (Nm) ............... 16.6-21.0 (22.6-28.4)
Cooling Fan Centrifugal Water Pump Bolts (M6), lb-ft (Nm) ............... 7.2-8.7 (9.8-11.8)
Starter Motor Structural Mounting Bracket Bolts (M10), lb-ft (Nm) ............... 33.0-43.0 (45.0-58.0)
Alternator Charging Unit Pivot Support Bolt (M10), lb-ft (Nm) ............... 33.0-43.0 (45.0-58.0)

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• Isuzu Engines Specs
  
• Isuzu 2AA1 Specs
  
• Isuzu 3AA1 Specs
  
• Isuzu 3AB1 Specs
  
• Isuzu 3CB1 Specs
  
• Isuzu 3CD1 Specs
  
• Isuzu 3CE1 Specs
  

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