This is the Isuzu Workshop Manual for the AU-4LE2 and BV-4LE2 industrial diesel engines, a 211-page PDF you can download and keep for reference. These common rail engines are used in generator sets and industrial machinery, and the manual carries them from engine mechanical work through the electrical, exhaust, lubrication, intake, and preheating systems.Inside you get the engine mechanical, cooling, fuel, and electrical sections plus dedicated exhaust, lubrication, intake, and preheating chapters. It includes compression figures, cylinder head bolt torque with angle tightening, valve clearance, injection timing and pressure, and the boost pressure and EGR control details for diagnosis and repair.For owners and mechanics servicing the 4LE2 in gensets or equipment, it provides the factory sequences and specifications needed to trace faults, set the engine correctly, and complete an overhaul.
What's Inside This Isuzu AU-4LE2, BV-4LE2 Manual
| System | Pages | Key Topics |
|---|---|---|
| Isuzu Diesel Engine | 39-49 | Function Check, Inspection Of Compression Pressure |
| Engine Exterior Equipment | 50-75 | Engine Accessories |
| Cylinder Head | 76-94 | Rocker Arm Shaft |
| Piston And Connecting Rod | 95-106 | Reassembly And Installation |
| Crankshaft Front Oil Seal | 107-114 | Flywheel |
| Timing Gear Train | 115-122 | Crankshaft Rear Oil Seal |
| Crankshaft | 123-134 | Camshaft |
| Special Tool | 135-138 | Cylinder Block |
| Cooling System | 139-148 | Service Precautions, Function Check, Water Pump, Thermostat |
| Fuel System | 149-162 | Service Precautions, Explanations on Functions and Operation, Governor, Components |
| Electrical System | 163-193 | Charging System, Generator (24V-30A), Generator (24V-50A), Generator (12V-20A) |
| Exhaust System | 194-199 | EGR Control, Connector Pin Layout, Boost Pressure Sensor Circuit Diagram, Inspection |
| Lubrication System | 200-204 | Service Precautions, Function Check, Oil Filter, Oil Pump |
| Intake System | 205-207 | - |
| Preheating System | 208-211 | Explanations on Functions and Operation |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Generator mounting bolt tightening torque (M10) | 41.2 — 55.0 N·m {4.2 — 5.6 kgf·m/ 30.4 — 40.6 lb·ft} | p. 167 |
| Cylinder head bolt tightening torque (M12 × 1.5) | 83.4 — 93.2 N·m {8.5 — 9.5/ 61.5 — 68.7} → 60° — 90° | p. 26 |
| Boost pressure sensor backup control (open circuit) | Control as the boost pressure is 15 kPa {2.2 psi} or more. | p. 197 |
| Lubrication oil pressure (at 1,000 rpm) | 147 {21} kPa {psi} | p. 36 |
| Thermostat working start temperature (at barometric pressure) | 82°C {180°F} | p. 32 |
| Compression Pressure (Standard) | 3.04 MPa | p. 25 |
| Compression Pressure (Service Limit) | 2.5 MPa | p. 25 |
| Cylinder Head Bolt Torque (M12 x 1.5) | 83.4 - 93.2 N·m, then angle tighten 60° - 90° | p. 26 |
| Valve Clearance (Cold) | 0.40 ± 0.05 mm | p. 41 |
| 4LE2X | ||
| Engine Oil Capacity | 9.3 - 12.1 L | p. 15 |
| Fuel Injection Timing (BTDC) | 2° | p. 49 |
| 4LE2N | ||
| Engine Oil Capacity | 5.9 - 8.4 L | p. 15 |
Isuzu AU-4LE2, BV-4LE2 Common Problems This Manual Covers
Engine starts then shuts down
A generator control panel fault can shut the engine down immediately after it starts, even when the engine itself is sound. The Electrical System section covers the charging system and generator wiring so the fault can be traced.
Manual Section: Electrical System p. 163Engine overheating
A cooling system failure such as a stuck thermostat or weak water pump drives temperature up and can lead to head gasket damage. The Cooling System section covers the water pump and thermostat, including the working start temperature.
Manual Section: Cooling System p. 139Common rail pressure fault
First stage, second stage, or excessive rail pressure faults cause power loss and stored codes on these engines. The Fuel System section covers the governor, injection timing, and fuel system operation and components.
Manual Section: Fuel System p. 149Hard cold starting
A failing preheat circuit leaves the 4LE2 slow to start in cold conditions. The Preheating System section explains the preheating function and operation for checking the circuit.
Manual Section: Preheating System p. 208Boost pressure sensor faults
A faulty boost pressure sensor or EGR control issue triggers backup control and reduced performance. The Exhaust System section covers EGR control, the boost pressure sensor circuit, and its inspection.
Manual Section: Exhaust System p. 194Low oil pressure
A worn oil pump or clogged filter drops lubricating oil pressure and risks bearing wear. The Lubrication System section covers the oil filter and oil pump service and function check.
Manual Section: Lubrication System p. 200Head gasket and compression loss
A failed head gasket or worn cylinders reduce compression and can accompany overheating. The Engine Mechanical section covers the cylinder head bolt torque with angle tightening and the engine internals.
Manual Section: Engine Mechanical p. 38Frequently Asked Questions
Which engines does this manual cover?
It covers the Isuzu AU-4LE2 and BV-4LE2 industrial diesel engines used in generator sets and machinery.
Does it include cylinder head torque specifications?
Yes. The Engine Mechanical section gives the cylinder head bolt torque with the angle tightening steps along with the other engine internals. p. 38
Does it help with overheating and cooling faults?
Yes. The Cooling System section covers the water pump and thermostat, including the thermostat working start temperature. p. 139
Does it cover the electrical and generator wiring?
Yes. The Electrical System section covers the charging system and the 12V and 24V generator variants used on these engines. p. 163
What do I get after purchasing this Isuzu AU-4LE2, BV-4LE2 manual?
You receive a 211-page searchable PDF, available for immediate download. Open it on any device, phone included. No shipping, no wait.
Is this Isuzu AU-4LE2, BV-4LE2 Workshop Manual printable?
Yes. The PDF carries no DRM restrictions. Print any page or section you need for shop use with any standard printer.
Does this Isuzu AU-4LE2, BV-4LE2 manual include wiring diagrams?
Yes. This manual includes full electrical wiring diagrams, wire routing, and connector pinouts for the 4LE2 engine.
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