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Isuzu 3LD2 Engine

The Isuzu 3LD2 is an industrial-grade, vertical in-line diesel engine engineered for high durability, structural rigidity, and optimal fuel efficiency. Operating on a 4-cycle principle, this unit features a compact 3-cylinder configuration widely deployed in heavy-duty agricultural machinery, construction equipment, and utility vehicles. The engine architecture emphasizes simplified maintenance accessibility and reliable performance under high intermittent loads. The engine utilizes an Overhead Valve (OHV) valvetrain layout driven by a gear-train-indexed camshaft, actuating two valves per cylinder.

The cylinder bore measures 83.1 mm and the piston stroke length is 92 mm. This internal dimension yields a total displacement profile of 1.496 liters with a compression ratio optimized at 18.8 to 1. The fuel system is built around a Direct Injection (DI) design utilizing a dedicated inline multi-plunger fuel injection pump assembly. Fuel delivery is managed by a mechanical governor responsive to load fluctuations, ensuring precise metering to the multi-hole injection nozzles for optimized combustion efficiency and lower exhaust emissions.

Forced-feed lubrication is delivered by a high-efficiency trochoid pump assembly driven by the crankshaft gear. The system features a full-flow cartridge oil filter, integrated pressure regulating valves, and a high-capacity steel oil pan designed to maintain structural oil pickup angles up to critical operational tilts. A liquid-cooled system relies on continuous forced circulation via a belt-driven centrifugal water pump. The coolant flow path routes through the cylinder block jacket directly up to the cylinder head channels, regulated by a wax-pellet type thermostat to guarantee stable thermal operational limits under continuous load profiles.

General Technical Data

Engine Specifications

Engine Model ............... Isuzu 3LD2
Engine Type ............... 4-cycle vertical 3-cylinder direct injection liquid-cooled diesel
Number of Cylinders ............... 3
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.27 (83.1)
Engine Stroke, in (mm) ............... 3.62 (92.0)
Displacement, cu.in (L) ............... 91.3 (1.496)
Rated Engine Power, hp (kW) ............... 38.9 (29.0)
Rated Engine Speed, rpm ............... 3250
Peak Torque ............... 97 Nm (71.5 lb-ft) at 1800 rpm
Idle Speed ............... 800-900 rpm
Aspiration Type ............... Naturally Aspirated
Operating Speed ............... 1500-3250 rpm
Compression Ratio ............... 18.8:1
Firing Order ............... 1-3-2
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Combustion Chamber Type ............... Direct injection
Valves per Cylinder ............... 2
Lubrication System ............... Full forced pressure feed type
Oil Pump Type ............... Trochoid type gear-driven by crankgear
Oil Filter Type ............... Full-flow spin-on cartridge
Cooling System ............... Liquid-cooled with pressurized water circulation
Water Pump Type ............... Belt-driven centrifugal vane type
Air Cleaner Type ............... Dry element cartridge
Starting System ............... Electric starter motor with glow plug aid
Electrical System ............... 12V negative ground
Alternator Output, A ............... 20

Fuel System

Fuel Injection Pump Type ............... Zexel Bosch PFR high pressure solid injection
Governor Type ............... Variable speed control mechanical governor
Fuel Feed Pump Type ............... Mechanical diaphragm type plunger pump
Injection Nozzle Type ............... Multi-hole direct injection nozzle type
Fuel Filter Type ............... Cartridge element spin-on type with water sedimenter
Injection Timing, deg BTDC ............... 14
Injection Opening Pressure, psi (MPa) ............... 2843 (19.6)
Fuel Return Line System ............... Overflow pipe style back to fuel tank
Recommended Fuel Grade ............... Diesel fuel SAE 2D Type
Maximum Fuel Inlet Restriction, in.Hg (kPa) ............... 2.95 (10.0)
Maximum Fuel Return Restriction, in.Hg (kPa) ............... 5.91 (20.0)
Minimum Fuel Transfer Pump Pressure, psi (kPa) ............... 2.9 (20.0)
Fuel Injection Line Inside Diameter Bore, in (mm) ............... 0.0590 (1.50)
Fuel Injection Line Outside Diameter Tubing, in (mm) ............... 0.2362 (6.00)
Fuel Feed Pump Diaphragm Stroke Reference, in (mm) ............... 0.0787 (2.00)

Dimensions and Weight

Overall Length, in (mm) ............... 23.1 (585)
Overall Width, in (mm) ............... 19.3 (490)
Overall Height, in (mm) ............... 24.1 (615)
Dry Weight, lbs (kg) ............... 290 (132)

Maintenance Data

Service Information

Compression Pressure, Standard, psi (MPa) ............... 441.0 (3.04)
Compression Pressure, Minimum Limit, psi (MPa) ............... 355.0 (2.45)
Oil Pressure Minimum at Idle, psi (kPa) ............... 14.2 (98.0)
Oil Pressure at Rated Speed, psi (kPa) ............... 42.7-56.9 (294.0-392.0)
Oil Temperature Maximum Limits, F (C) ............... 248.0 (120.0)
Thermostat Opening Temperature, F (C) ............... 170.0 (76.5)
Thermostat Full Open Temperature, F (C) ............... 194.0 (90.0)
Coolant Temperature, Max Limits, F (C) ............... 212.0 (100.0)
Cooling System Pressure Cap Release Point, psi (kPa) ............... 12.8-15.6 (88.3-107.9)
Cooling V Belt Tension Deflection, in (mm) ............... 0.394-0.472 (10.00-12.00)
Intake Valve Clearance, Cold, in (mm) ............... 0.008 (0.20)
Exhaust Valve Clearance, Cold, in (mm) ............... 0.008 (0.20)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, or SAE 15W-40
API Service Classifications ......................... CC, CD, or CE
Engine Oil Capacity, Pan Only, qt (L) ............... 6.66 (6.3)
Engine Oil Capacity, Total System, qt (L) ............... 7.40 (7.0)
Coolant Capacity, Engine Only, qt (L) ............... 2.64 (2.5)

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 1000 hours
Compression test ............... Every 1000 hours
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Bore Standard Diameter, in (mm) ............... 3.2716-3.2728 (83.100-83.130)
Cylinder Bore Wear Maximum Limit, in (mm) ............... 0.0078 (0.20)
Cylinder Head Deck Surface Flatness, in (mm) ............... 0.0020 (0.05)
Crankshaft Main Bearing Clearance, in (mm) ............... 0.0015-0.0031 (0.039-0.079)
Crankshaft End Play, in (mm) ............... 0.0023-0.0094 (0.060-0.240)
Crankshaft Journal Runout, in (mm) ............... 0.0008 (0.02)
Crankshaft Main Journal Diameter, in (mm) ............... 2.438 (61.92)
Crankshaft Main Bearing Bore Housing ID, in (mm) ............... 2.5984-2.5992 (66.000-66.020)
Crankshaft Thrust Journal Width Rear, in (mm) ............... 1.1811-1.1835 (30.000-30.060)
Crankshaft Main Journal Taper Limit, in (mm) ............... 0.0004 (0.01)
Crankpin Rod Journal Oil Clearance, in (mm) ............... 0.0014-0.0029 (0.035-0.074)
Crankpin Journal Diameter, in (mm) ............... 1.887 (47.92)
Connecting Rod Small End Bore, in (mm) ............... 1.1027-1.1035 (28.010-28.030)
Connecting Rod Crankpin Bearing Clearance, in (mm) ............... 0.0014-0.0029 (0.035-0.074)
Connecting Rod Big End Inside Diameter, in (mm) ............... 2.0078-2.0086 (51.000-51.020)
Piston Outside Diameter, in (mm) ............... 3.2693-3.2705 (83.040-83.070)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0023-0.0035 (0.060-0.090)
Piston Pin Outside Diameter, in (mm) ............... 1.1020-1.1024 (27.992-28.000)
Piston Pin Small End Bushing Clearance, in (mm) ............... 0.0003-0.0011 (0.008-0.028)
Piston Pin Bushing Bore Diameter, in (mm) ............... 1.103 (28.02)
Top Ring Groove Width, in (mm) ............... 0.0807-0.0815 (2.050-2.070)
Second Ring Groove Width, in (mm) ............... 0.0602-0.0610 (1.530-1.550)
Oil Ring Groove Width, in (mm) ............... 0.1583-0.1591 (4.020-4.040)
Top Ring Side Clearance, in (mm) ............... 0.0024-0.0039 (0.060-0.100)
Second Ring Side Clearance, in (mm) ............... 0.0016-0.0031 (0.040-0.080)
Oil Ring Side Clearance, in (mm) ............... 0.0008-0.0024 (0.020-0.060)
Top Ring End Gap, in (mm) ............... 0.0078-0.0137 (0.200-0.350)
Second Ring End Gap, in (mm) ............... 0.0078-0.0137 (0.200-0.350)
Oil Ring End Gap, in (mm) ............... 0.0078-0.0157 (0.200-0.400)
Cylinder Head Valve Guide Bore ID, in (mm) ............... 0.4724-0.4731 (12.000-12.018)
Cylinder Block Tappet Bore ID, in (mm) ............... 0.8267-0.8278 (21.000-21.021)
Intake Valve Guide to Stem Clearance, in (mm) ............... 0.0011-0.0025 (0.030-0.064)
Exhaust Valve Guide to Stem Clearance, in (mm) ............... 0.0015-0.0029 (0.040-0.074)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.2740-0.2746 (6.961-6.975)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.2732-0.2740 (6.940-6.960)
Valve Thickness Head, in (mm) ............... 0.0394 (1.00)
Valve Spring Free Lenght, in (mm) ............... 1.5315 (38.90)
Valve Guide Outside Diameter, in (mm) ............... 0.4732-0.4739 (12.020-12.038)
Valve Guide Housing Bore Inside Diameter, in (mm) ............... 0.4716-0.4724 (11.980-12.000)
Intake Valve Seating Width, in (mm) ............... 0.0551 (1.40)
Exhaust Valve Seating Width, in (mm) ............... 0.0551 (1.40)
Camshaft Front Journal Outside Diameter, in (mm) ............... 1.5716-1.5724 (39.920-39.940)
Camshaft Center Journal Outside Diameter, in (mm) ............... 1.5323-1.5331 (38.920-38.940)
Camshaft Rear Journal Outside Diameter, in (mm) ............... 1.4929-1.4937 (37.920-37.940)
Camshaft Journal Clearance, in (mm) ............... 0.0009-0.0033 (0.024-0.084)
Cam Lobe Height, Intake, in (mm) ............... 1.4114 (35.85)
Cam Lobe Height, Exhaust, in (mm) ............... 1.4114 (35.85)
Rocker Arm Shaft Outside Diameter, in (mm) ............... 0.4716-0.4724 (11.980-12.000)
Rocker Arm Bushing Bore Clearance, in (mm) ............... 0.0004-0.0019 (0.010-0.050)
Tappet Outside Diameter, in (mm) ............... 0.8252-0.8260 (20.960-20.980)
Tappet to Block Bore Clearance, in (mm) ............... 0.0008-0.0028 (0.020-0.071)
Idler Gear Shaft Outside Diameter, in (mm) ............... 1.3366-1.3374 (33.950-33.970)
Idler Gear Bushing Clearance, in (mm) ............... 0.0011-0.0027 (0.030-0.070)
Timing Gear Backlash, in (mm) ............... 0.0020-0.0059 (0.050-0.150)

Tightening Torques

Cylinder Head Bolts (Stage One), lb-ft (Nm) ............... 22.1 (30.0)
Cylinder Head Bolts (Stage Two), lb-ft (Nm) ............... 44.2 (60.0)
Cylinder Head Cover Cap Nuts, lb-ft (Nm) ............... 5.9-8.8 (8.0-12.0)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 62.7-69.9 (85.0-95.0)
Connecting Rod Cap Nuts, lb-ft (Nm) ............... 32.5-39.8 (44.1-54.0)
Flywheel Mounting Bolts, lb-ft (Nm) ............... 57.9-65.1 (78.5-88.3)
Crankshaft Pulley Center Bolt, lb-ft (Nm) ............... 83.3-97.6 (113.0-132.3)
Camshaft Thrust Plate Bolts, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Camshaft Timing Gear Bolt, lb-ft (Nm) ............... 54.2-61.5 (73.5-83.3)
Idler Gear Shaft Bolts, lb-ft (Nm) ............... 19.3-25.3 (26.2-34.3)
Timing Gear Case Mounting Bolts, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Timing Gear Case Cover Bolts, lb-ft (Nm) ............... 5.9-8.8 (8.0-12.0)
Oil Pump Stator Assembly Screws, lb-ft (Nm) ............... 5.9-8.8 (8.0-12.0)
Oil Pan Drain Plug, lb-ft (Nm) ............... 36.1-43.4 (49.0-58.8)
Oil Pan Outer Mounting Screws, lb-ft (Nm) ............... 5.9-8.8 (8.0-12.0)
Oil Pressure Regulator Valve Plug, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Rocker Arm Shaft Bracket Bolts, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Valve Clearance Adjusting Jam Nuts, lb-ft (Nm) ............... 11.6-14.5 (15.7-19.6)
Fuel Injection Pump Mount Bolts, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Fuel Injection Pump Drive Gear Nut, lb-ft (Nm) ............... 28.9-36.1 (39.2-49.0)
Fuel Injection Nozzle Holder Retainer, lb-ft (Nm) ............... 36.1-43.4 (49.0-58.8)
Fuel Injection Nozzle Case Retaining Nut, lb-ft (Nm) ............... 21.7-28.9 (29.4-39.2)
Fuel Injection High Pressure Lines Nuts, lb-ft (Nm) ............... 18.1-21.7 (24.5-29.4)
Fuel Overflow Return Line Pipe Coupler Bolt, lb-ft (Nm) ............... 14.5-18.1 (19.6-24.5)
Glow Plugs Shell Thread Installation, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Glow Plug Electrical Harness Small Nuts, lb-ft (Nm) ............... 0.7-1.1 (1.0-1.5)
Cooling Water Pump Mounting Bolts, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Cooling Fan Pulley Set Bolts, lb-ft (Nm) ............... 5.9-8.8 (8.0-12.0)
Thermostat Housing Water Outlet Outlet, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Intake Manifold Securing Screws, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Exhaust Manifold Securing High Temp Nuts, lb-ft (Nm) ............... 15.2-21.7 (20.6-29.4)
Starter Motor Frame Mounting Stud Nuts, lb-ft (Nm) ............... 36.1-47.0 (49.0-63.7)
Starter Motor Electrical B Terminal Nut, lb-ft (Nm) ............... 5.9-8.8 (8.0-12.0)
Alternator Pivot Mount Bracket Long Bolt, lb-ft (Nm) ............... 28.9-39.8 (39.2-54.0)
Alternator Adjusting Link Locking Bolt, lb-ft (Nm) ............... 13.7-21.0 (18.6-28.4)
Oil Pressure Switch Sensor Unit Port Thread, lb-ft (Nm) ............... 10.8-14.5 (14.7-19.6)
Exhaust Pipe Flange Coupling Nut, lb-ft (Nm) ............... 19.3-25.3 (26.2-34.3)
Flywheel Housing Structural Face Bolts, lb-ft (Nm) ............... 36.1-47.0 (49.0-63.7)

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• Isuzu Engines Specs
  
• Isuzu 3KC1 Specs
  
• Isuzu 3KC2 Specs
  
• Isuzu 3KR1 Specs
  
• Isuzu 3KR2 Specs
  
• Isuzu 3LB1 Specs
  
• Isuzu 3LD1 Specs
  

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