Isuzu 4LE2, AU-4LE2, BV-4LE2 Industrial Diesel Engine Workshop Manual (P/N 4LE2IT4-WE-0991)

Isuzu Motors Limited published this workshop manual in March 2009 for the AU-4LE2 and BV-4LE2 industrial diesel engines. Version 4LE2IT4-WE-0991 identifies the 4LE2X and 4LE2N configurations in its specifications and repair sections.

Supplied as a single 211-page PDF.

• Engine repair: Cylinder-head, rocker-arm shaft and piston/connecting-rod overhaul, with timing-gear, camshaft, crankshaft, cylinder-block, flywheel and front/rear crankshaft oil-seal procedures.

• Fuel injection: Injection-timing inspection and shim adjustment, pump removal/installation, nozzle spray checks, fuel-system bleeding, electromagnetic-pump testing and governor disassembly/reassembly.

• Cooling and lubrication: Cooling-system leak tests, EGR-cooler air bleeding, water-pump and thermostat inspection, oil-pressure specifications and oil-pump clearance checks.

• Intake and EGR: Turbocharger shaft-play inspection, EGR-valve checks, controller wiring, connector pin identification and sensor-circuit diagrams.

• Charging and starting: Generator bench tests, starter tests, charging-system fault diagnosis and glow-plug/preheating troubleshooting.

• Factory repair data: Component torque tables, nominal dimensions, assembly specifications, service limits, repair criteria and special-tool references.

The repair procedures suit experienced diesel technicians equipped for precision engine measurements and electrical testing.

Engine Variants and Mechanical Repair

The 4LE2X exterior drawings identify the turbocharger, EGR cooler and cut solenoid, intake chamber, PCV valve, injection-pump plumbing and oil cooler. Separate drawings show the 4LE2N layout.

Specification tables distinguish compression ratios, coolant and oil capacities, and oil-pump specifications. Machine-dependent values refer to the equipment manufacturer's specifications.

Cylinder head and pistons: Coverage extends from removal and disassembly through inspection, reassembly and installation. Head work includes valve-seat inspection, valve-guide and seal service, head-gasket installation and valve-clearance inspection/adjustment. Compression testing is also documented.

Piston and connecting-rod procedures cover ring and pin removal, piston-to-bore and bearing-clearance checks, rod alignment, bushing replacement and piston/ring assembly. Separate standards for 25 mm and 27 mm connecting-rod small ends help match piston-pin, bearing and cap-bolt specifications to the assembly being repaired.

The ring sections distinguish compression-ring profiles and orientation marks, and link inverted installation to increased oil consumption. Exploded views illustrate the cylinder head, pistons/connecting rods and timing gear train.

Injection Pump, Nozzles and Governor

The Fuel System Diagram shows the fuel filter, sedimenter, injection pump and nozzle holder. The system uses Bosch-type PFR1KX pumps, a centrifugal all-speed governor and multi-hole nozzle holders; sedimenter cleaning and service are covered.

Pump-installation cautions explain how control-link and rack-pin misalignment can trap the rack pin or bend the link.

Specialist work: Two-stage nozzle disassembly is excluded from shop service; nozzle overhaul and injection-pressure inspection/adjustment are assigned to a BOSCH service center. Injection-pump faults are routed to a specialty shop, with no internal pump rebuild procedure.

Exploded governor drawings accompany the disassembly and reassembly procedures. Adjustment requires an engine performance test; the manual prohibits disassembly if that test cannot be performed afterward.

Cooling, Lubrication and Turbocharger Inspection

Cooling coverage includes coolant-concentration checks and fan-clutch testing. Lubrication coverage identifies the full-flow/bypass filtration arrangement, water-cooled oil cooler and piston-cooling oil jet, with an exploded oil-pump view and rotor-clearance limits.

The liquid-gasket precautions explain how excess sealant can block oil galleries or piston-cooling jets and cause seizure, while insufficient sealant can cause oil or water leaks.

The turbocharger section pairs an exploded component view with turbine-shaft axial-play inspection and a dial-gauge reference.

Electrical Diagnosis and EGR Schematics

Troubleshooting charts address failure to start, irregular engine speed, low output, overheating, abnormal exhaust smoke, battery over-discharge, low oil pressure, excessive fuel or oil consumption and engine knocking.

Generators: Repair data separates the Mitsubishi 24V-30A, Nikko 24V-50A and Hitachi 12V-20A units, with connector terminals, internal connections, test information and maintenance standards.

Starters: Mitsubishi 24V-3.2kW coverage includes no-load testing. The DENSO 12V-2.0kW section provides pull-in, hold-in and return tests, while referring internal repair to a DENSO service station.

The EGR Controller Wiring Diagram and Connector Pin Layout support circuit tracing. Related drawings include the Engine Coolant Temperature Sensor Circuit Diagram, Tachosensor Circuit Diagram and Boost Pressure Sensor Circuit Diagram.

The controller-to-EGR-cut-solenoid harness belongs to the machine installation; harness faults are referred to the machine manufacturer.

Special Tools and Service Precautions

Compression-testing tools include gauge 5-8840-2675-0 and adapter 5-8840-9029-0. Fuel and valve tools include nozzle tester 5-8840-9016-0, valve spring remover 5-8840-9030-0 and valve guide installer 5-8840-9035-0.

Piston ring compressor 5-8840-9018-0 and front/rear oil-seal installers 5-8840-9031-0 / 5-8840-9032-0 are also identified.

The manual's precautions address high-pressure fuel injection, hot coolant, rotating components and electrical service, including injection injuries and fire hazards from fuel leakage.

File Format and Readability

The page total includes the front and rear covers (2 pages), publication page (1 page) and two section-end pages containing only headers.

Text search: Main section text is searchable; cover text and some diagram and troubleshooting-chart labels are not.

Navigation: Eleven numbered PDF bookmarks provide jumps at 20-page intervals without chapter names.

Diagram readability: Small EGR wiring, connector-pin and generator-circuit labels need zooming for comfortable reading.