Part of the Hitachi Repair Manuals.
All 269 pages of this Hitachi EX8-2B Technical Manual PDF cover one machine: your EX8-2B hydraulic excavator, from pump device to travel motor. Inside you get the full hydraulic circuit diagrams, electrical circuit and main harness schematics, exploded views of the pump, control valve, and swing device, plus a complete troubleshooting section with diagnosing procedures and electrical system inspection. Operational performance tests are here too: engine test, excavator test, and component standards, so you can prove the repair actually worked. Torque the 19 mm hydraulic hose union joints to 29.5 Nm, then set the 30-degree male unions at 59 Nm and the 37-degree females at 44 Nm. No more chasing wiring faults with a multimeter and a prayer. Bookmarked and text-searchable; download it, pull it up on your phone next to the machine, and start wrenching.
What's Inside This Hitachi EX8-2B Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 2-11 | Specifications, Component Layout |
| System | 12-15 | Hydraulic System |
| Component Operation | 16-37 | Pump Device, Swing Device, Control Valve, Travel Device, Others |
| Operational Performance Test | 38-67 | Introduction, Engine Test, Excavator Test, Component Test, Standard |
| Troubleshooting | 68-97 | Diagnosing Procedure, Troubleshooting a, Troubleshooting B, Electrical System Inspection |
| The Attached Diaglam List | 98-103 | Electrical Circuit Diagram, Main Harness, Hydraulic Circuit |
| General Information | 104-117 | Tightening |
| Upperstructure | 118-137 | Pump Device, Control Valve, Swing Device |
| Undercarriage | 138-155 | Travel Device, Center Joint |
| Front Attachment | 156-169 | Cylinder |
| Engine and Accessory | 170-269 | Engine Body, Lubication System, Cooling System, Fuel System, Electrical System, General, Lubricating System |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Track Shoe Width | 180 mm (0’ 7”) | p. 4 |
| Battery voltage | 12 V | p. 75 |
| Hydraulic hoses and union joints torque (19 mm) | 29.5 Nm | p. 111 |
| 30° male union joint torque (19 mm) | 59 Nm | p. 114 |
| 37° female union joint torque (19 mm) | 44 Nm | p. 114 |
| Sprocket Dimension D Standard | 291.0 mm | p. 151 |
| Pin A Standard | 25 mm | p. 163 |
| Bushing (Boom) A Standard | 25 mm | p. 163 |
| Injection pump fuel pressurization | 13.73 to 14.71 MPa (140 to 150 kgf/cm², 1991 to 2062 psi) | p. 188 |
| Air pressure at the nozzle (for cleaning) | 690 kPa (7kgf/cm2, 100 psi) | p. 216 |
| Engine Rated Horsepower | 6.4 kW/2450 min-1 | p. 4 |
| Machine Weight (Standard) | 740 kg | p. 4 |
Hitachi EX8-2B Common Problems This Manual Covers
Hitachi EX8-2B hydraulics slow and weak in all functions, bucket loses digging power under load
Check hydraulic oil level and top off before anything else. Inspect the suction line and replace clogged hydraulic filters. Test main relief valve pressure against the 17.2 MPa specification on page 67 with a gauge on the pump outlet. If pressure reads low, follow the diagnosing procedure in the troubleshooting section starting on page 68.
Manual Section: Troubleshooting p. 67Hydraulic oil leaking at hose fittings, reservoir level drops between daily checks
Wipe the fittings clean and cycle the machine to find the leak source. Retorque 19 mm hydraulic hose union joints to 29.5 Nm per the chart on page 111; O-ring seal joints take 59 Nm, listed on page 115. Replace any hose with a cracked or weeping outer cover, never patch it.
Manual Section: General Information p. 111Engine down on power after startup, black exhaust smoke, machine feels sluggish under load
Remove the air filter element and clean it with compressed air from the inside out, keeping nozzle pressure below 690 kPa (100 psi) as specified on page 216. Replace the fuel filter and drain any water and sediment from the tank. If power stays low, work through the engine troubleshooting charts before pulling injectors.
Manual Section: Engine and Accessory p. 216Tracks keep coming loose and wearing unevenly, machine pulls to one side when traveling
Clean packed mud and debris out of the undercarriage daily before adjusting anything. Check track tension on both sides and reset it evenly. Measure sprocket dimension D; standard is 291.0 mm and the allowable limit is 286.0 mm, both on page 151. Replace sprockets and worn track components as a set to stop repeat failures.
Manual Section: Undercarriage p. 151Starter clicks but engine will not turn over, no crank even with lights on
Test battery voltage first; the system runs on 12 V, and a weak reading under load means charging or replacing the battery. Clean and tighten both terminals. Work through the chart on page 75 covering the key switch, starter relay, and fusible link in order before condemning the starter motor.
Manual Section: Starter Does Not Rotate p. 75Frequently Asked Questions
What is the torque specification for the main pump mounting bolts on a Hitachi EX8-2B?
The torque specification for the pump mounting bolts (item 6) is 9.8 N·m (1 kgf·m, 7.2 lbf·ft). p. 110
What are the hydraulic pressure specifications for the main relief valve on a Hitachi EX8-2B?
The main relief pressure is 17.2 ± 1.0 MPa (175 ± 10 kgf/cm²). p. 67
What is the standard valve clearance for the engine on a Hitachi EX8-2B?
The standard valve clearance for both intake and exhaust valves is 0.145 to 0.185 mm (0.0057 to 0.0073 in). p. 66
What is the recommended engine oil change interval for the Hitachi EX8-2B?
Engine oil should be changed every 100 hours of operation. p. 214
What is the correct injection timing for the engine on a Hitachi EX8-2B?
The injection timing is 17° before top dead center. p. 66
Is this Hitachi EX8-2B Technical Manual a digital download?
You get a 269-page searchable PDF that downloads instantly after checkout. Open it on your laptop, tablet, or phone, and bring it right to the shop floor.
Are there any print restrictions on this Hitachi EX8-2B manual?
Yes, print as many copies as you want, and there are no restrictions. Many mechanics print the section they need and bring it to the shop floor.
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