1988–1991 Hitachi EX300, EX300LC Excavator Service Manual

This Hitachi service manual covers the 1988–1991 EX300 and EX300LC excavators with standard and long-crawler undercarriages. It uses the Super Deluxe configuration as its reference; equipment varies by machine and market.

• Hydraulic pumps and valves: Main-pump and regulator disassembly, inspection and assembly, HY-ZFS gear-pump service, and KVMG-270-HC control-valve repair.

• Swing and travel: Swing-motor and reduction-device overhaul, HMT134CF travel-motor service, parking-brake components, and center-joint disassembly and assembly.

• Undercarriage and attachments: Track-frame, idler, roller and track-link service, plus boom, arm, bucket, hydraulic-cylinder, pin and bushing work.

• Engine and fuel system: Hino EP100-T internal engine repair, injection-pump and governor adjustment, cooling-system service, and RHC7 turbocharger inspection.

• Electrical diagnosis: E-P control, auto-idle and travel-speed circuits, monitor and alarm troubleshooting, wiring diagrams, and starter and charging-system tests.

• Performance testing: Pump-flow, relief-pressure and motor-drain measurements, attachment cycle-time checks, and component-specific standards for evaluating wear and performance.

Written for training new service personnel and as a reference for experienced service technicians, the manual combines operating principles with shop and field-service procedures.

Hydraulic Pump Repair and Fault Isolation

The hydraulic chapters explain main and pilot circuits, pump-displacement control, and single and combined operations. Separate procedures cover the control neutralizer valve, shockless valve and pilot valves.

Pump P-Q curves, flow-rate/pilot-pressure charts and hydraulic circuit schematics support the test procedures. Fault charts for slow front-attachment movement distinguish pilot-supply, control, engine-speed and pump/regulator causes, helping technicians narrow the fault before selecting a component for overhaul.

Assembly details: The pump-transmission instructions identify seal-lip damage as a risk during assembly over the shaft and specify protective tooling, including ST-2280. The control-valve inspection section also explains that its spools are selectively fitted to the housing and are not supplied individually for field replacement.

Swing, Undercarriage and Front-Attachment Service

Swing-motor specifications distinguish MX200CAB-10A-01/250 units from M2X210CAB-10A-02/250 units by EX300 serial number. Those assignments help match the installed motor to its specifications before service.

The travel-drive material includes motor and brake-valve disassembly, planetary reduction-device assembly and center-joint seal work. Shared component chapters contain model-specific applications, so their other machine references do not extend coverage to the entire EX series.

Boom, arm and bucket sections document assembly and piping arrangements. Cylinder procedures address seals, rod condition and bore wear, while undercarriage chapters cover track links, rollers, idlers and adjusters. Working on heavy machinery involves significant physical risks; follow the manual's support and hydraulic-pressure precautions before hands-on maintenance.

Hino Engine Overhaul and Fuel-Injection Work

Internal engine coverage extends through the cylinder head and valve mechanism, timing gears, camshaft, cylinder block, pistons and crankshaft. Lubrication and cooling sections cover the oil pump, oil cooler, coolant pump and thermostat. Engine performance curves and service-standard tables accompany the inspection material.

Injection equipment: Separate sections describe injection-pump overhaul, nozzle inspection, injection-timing adjustment and RSV governor calibration. These procedures require dedicated test equipment; the governor chapter directs sealed adjustments to authorized Hino or pump-manufacturer service stations and warns that unauthorized readjustment can cause engine failure.

Starter, generator and turbocharger chapters include troubleshooting and overhaul or inspection procedures.

E-P Control and Monitor Troubleshooting

Electrical documentation includes the overall Electrical Circuit diagram and a dedicated Starting Circuit schematic. Monitor tests address gauges, warning lamps and the buzzer.

Control-system diagnosis provides separate paths using a volt-ohm meter or the MECHATRO CHECKER. Auto-idle, mode switching and travel-speed change are covered individually, with electrical measurement standards and engine-control-device adjustment procedures.

Examples from Torque and Fluid-Capacity Tables

The tightening-torque reference distinguishes swing-bearing bolts at the track frame, listed at 931 N.m, from those at the main frame, listed at 735 N.m.

The engine specification table lists a maximum oil quantity of 28 liters. Cooling-water capacities are listed separately as 15.5 liters for the engine and 11.4 liters for the radiator. The hydraulic tank capacity is 265 liters at the standard level. Maintenance schedules and conversion tables accompany these reference sections.

Bookmarks, Diagram Detail and PDF Contents

Search and diagram navigation: PDF text search is unavailable. Embedded bookmarks cover the main sections and many component procedures. The electrical-specifications bookmark lands two pages beyond the section opening. Small wiring labels require enlargement, and some fine lettering remains faint.

The download contains one printable 1,033-page PDF, with the engine section included in the same file.