Part of the Isuzu 4BG1, Isuzu 6BG1 engine documentation.
This is the Isuzu Workshop Manual (publication IDE-2370) for the BG1-family industrial diesel engines, covering the AA-4BG1T, AA-6BG1, BB-4BG1T and BB-6BG1T models built from 1999. Its 220 pages take you from maintenance through full engine disassembly, inspection and repair, and reassembly, with the AA-4BG1T and BB-4BG1T being the turbocharged versions.System chapters cover the lubricating, cooling and fuel systems, the turbocharger, the air compressor and the engine electricals, followed by troubleshooting and a detailed repair standards section. Key data is here too, including cold valve clearance of 0.40 mm, injection starting pressure of 18.1 MPa and torque figures for the cylinder head, connecting rods, flywheel and main bearing caps.For anyone maintaining or rebuilding one of these four-cylinder and six-cylinder Isuzu industrial engines, this PDF supplies the factory procedures, service limits and settings needed to do the work properly.
What's Inside This Isuzu AA-4BG1T, AA-6BG1, BB-4BG1T, BB-6BG1T Manual
| System | Pages | Key Topics |
|---|---|---|
| Maintenance | 28-47 | Lubricating System, Fuel System, Cooling System, Injection Timing |
| Engine Assembly I (Disassembly) | 48-63 | External Parts Disassembly Steps, Major Components, Rocker Arm and Shaft Disassembly, Cylinder Head Disassembly |
| Engine Assembly Ii (Inspection & Repair) | 64-93 | Cylinder Head, Valve Guide, Valve Spring, Tappet |
| Engine Assembly Iii (Reassembly) | 94-123 | Piston and Connecting Rod Reassembly, Cylinder Head Reassembly Steps, Rocker Arm and Rocker Arm Shaft Reassembly, Major Component Reassembly Steps I |
| Lubricating System | 124-129 | - |
| Cooling System | 130-133 | General Description, Thermostat |
| Fuel System | 134-143 | General Description, Injection Nozzle, Injection Pump Calibration Data |
| Turbocharger | 144-147 | General Description, Turbocharger Identification, Inspection and Repair |
| Air Compressor | 148-155 | General Description, Disassembly Steps, Inspection and Repair, Reassembly Steps |
| Engine Electricals | 156-163 | Starter Identification, Starter Main Data and Specifications, Starter Motor Sectional View, Alternator Identification |
| Troubleshooting | 164-187 | Hard Starting, Unstable Low Idling, Insufficient Power, Excessive Fuel Consumption |
| Special Tool List | 188-191 | - |
| Repair Standards | 192-211 | General Rules, Engine Body, Main Operating Parts, Valve System |
| Conversion Table | 212-220 | - |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Crankshaft Bearing Cap Bolt Torque | 226-245 (23.0-25.0/166-181) N·m (kgf·m/lb.ft) | p. 104 |
| Connecting Rod Bolt Torque and Angle | 1st step 39 (4/29) N·m (kgf·m/lb.ft), 2nd step 60°–90° | p. 105 |
| Valve Clearance (At cold) | 0.40 mm | p. 7 |
| Compression Pressure (At warm) | 3.0 MPa | p. 7 |
| Injection Starting Pressure | 18.1 MPa | p. 7 |
| Compression Pressure Limit | 2.5 MPa | p. 42 |
| Thermostat Valve Opening Temperature | 80-84 °C | p. 34 |
| Rocker Arm Screw Lock Nut Torque | 21-30 N·m | p. 36 |
| BB-6BG1T | ||
| Lubricating Oil Volume | 21.5 L | p. 8 |
| AA-6BG1, BB-6BG1T | ||
| Coolant Volume (engine only) | 12 L | p. 8 |
| Flywheel Bolt Torque | 197-240 N·m | p. 108 |
| Crankshaft Pulley Nut Torque | 539-637 N·m | p. 109 |
Isuzu AA-4BG1T, AA-6BG1, BB-4BG1T, BB-6BG1T Common Problems This Manual Covers
Hard starting on BG1 engines
Worn injection nozzles, weak pump delivery or a tired battery leave these engines cranking without firing. The troubleshooting section works through hard starting and the related fuel and electrical checks.
Manual Section: Troubleshooting p. 164Overheating and thermostat failure
Coolant leaks, a clogged radiator or a stuck thermostat push temperature past the normal range. The cooling system section covers the thermostat, which opens at 80 to 84 degrees C.
Manual Section: Cooling System p. 130Injector and fuel system faults
Dirty injection nozzles and clogged fuel lines cause rough running, smoke and lost power. The fuel system section covers the injection nozzle and injection pump calibration data.
Manual Section: Fuel System p. 134Turbocharger wear on T models
On the turbocharged AA-4BG1T and BB-4BG1T, bearing or shaft wear shows up as smoke, whine or lost boost. The turbocharger section covers identification, inspection and repair.
Manual Section: Turbocharger p. 144Low compression and cylinder wear
High-hour engines lose compression through worn liners, rings and valves. The inspection and repair section measures the cylinder head, valve guide, valve spring and tappet against the limits, with the compression limit at 2.5 MPa.
Manual Section: Engine Assembly II (Inspection & Repair) p. 64Air compressor faults on air-braked units
Engines driving an air compressor can build pressure slowly or pass oil from worn internals. The air compressor section covers disassembly, inspection and repair, and reassembly.
Manual Section: Air Compressor p. 148Frequently Asked Questions
Which engines does this manual cover?
It covers the Isuzu AA-4BG1T, AA-6BG1, BB-4BG1T and BB-6BG1T industrial diesel engines from 1999 onward, published under Isuzu number IDE-2370. The AA-4BG1T and BB-4BG1T are the turbocharged models.
Does it include torque specifications?
Yes. The reassembly and repair standards sections carry the torque data, including a cylinder head first step of 69 N-m, connecting rod first step of 39 N-m and main bearing cap bolt torque of 226 to 245 N-m.
What are the valve clearance and injection settings?
The maintenance section covers injection timing and adjustment, with cold valve clearance of 0.40 mm and an injection starting pressure of 18.1 MPa for these engines. p. 28
Is a troubleshooting guide included?
Yes. The troubleshooting section covers hard starting, unstable low idling, insufficient power and excessive fuel consumption, directing you to the system at fault. p. 164
How will I receive this Isuzu AA-4BG1T, AA-6BG1 Workshop Manual?
Instant PDF download. The full 220-page searchable Workshop Manual is available immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Am I able to print pages from this manual?
Yes, print as many copies as you need. There are no restrictions. Many mechanics print the section they need and bring it to the shop floor.
Are there wiring harness diagrams in this Isuzu AA-4BG1T, AA-6BG1 manual?
Yes. This manual includes complete electrical wiring diagrams, wire routing, and connector pinouts.
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