Kobelco SK100, SK120, SK120LC Excavator 1990–1996 Shop Manual (P/N S5LP0105E)

This Kobelco factory shop manual covers SK100 (YW), SK120 (LP), and SK120LC (YP) crawler excavators in a 775-page PDF. It is suited to mechanics familiar with excavator hydraulics and equipped for pressure testing, precision measurement, and heavy component handling.

• Engine overhaul procedures cover disassembly, inspection, repair, and reassembly of the cylinder head, pistons, liners, crankshaft, and timing gears.
• Hydraulic component service includes the K3V63DT main pump, KR36-9C regulator, KMX13 control valve, and TH40K pilot valve, with internal inspection and adjustment procedures.
• Swing and travel sections address motor overhaul, planetary reduction gear repair, parking brakes, and swing-ring replacement.
• Undercarriage work covers track links, upper and lower rollers, idlers, track-tension assemblies, and sprocket removal and installation.
• Attachment procedures include boom, arm, and bucket removal, pin-and-bushing inspection, and bucket clearance adjustment. Separate chapters cover hydraulic-cylinder and swivel-joint seal replacement and leakage testing.
• KPSS mechatro-controller adjustment covers engine stop and high-speed positions and engine-speed settings for H, S, and FC modes, including setup after controller or stepping-motor replacement. Control-system service also includes throttle-potentiometer adjustment.
• Pump-drive coupling and radiator service accompany removal and installation procedures for the cab, counterweight, and upper frame.

Model Coverage and Publication Details

The main applicability index lists YW-03371 onward, LP-06191 onward, and YP-01601 onward. Selected component chapters also cover earlier YW-2801 and LP-5201 machines; applicability varies by section.

The overall index carries Book Code S5LP0005E②. S5LP0105E① identifies the Specifications section. The PDF contains 550 pages of Kobelco machine and component material, including front matter; the 213-page Isuzu engine manual IDE-2041; and a 12-page Flywheel P.T.O. supplement.

Hydraulic Testing and Component Repair

Pressure-measurement procedures cover main, travel, swing, pilot, and negative-control relief circuits. Performance tests address cylinder speed and drift, swing braking, travel straightness, motor case-drain flow, and swing-bearing play. Troubleshooting flowcharts trace weak attachment response, travel faults, and engine starting problems.

Separate SK100 and SK120 Hydraulic System Diagrams explain straight-travel priority, swing priority, and arm regeneration. Pump Control Curves document regulator behavior under different control conditions.

Swing-relief procedures distinguish earlier screw-adjusted valves from shim-adjusted valves beginning at LP-06925 and YP-01641. Gear-pump assembly notes explain how reversing the balance seal can cause the gears to seize.

Isuzu Engine Service and Repair Limits

Engine specifications detail the Isuzu 4BD1 powerplant for the SK100, while separating the requirements for the turbocharged 4BD1T found in the SK120 and SK120LC. The included engine book contains shared 4B/6B-series material, so its application tables distinguish the relevant engine versions.

Fuel-system work includes injection-timing adjustment, nozzle inspection and testing, and fuel-system bleeding. Compression testing, valve-clearance adjustment, oil-pump inspection, and water-pump service are also covered. Piston-selection notes identify the seizure risk from using the wrong piston grade.

Turbocharger inspection is included. Detailed 4BD1T turbocharger repair is referred to the separate IHI manual RHB6A-SER-TC-141, which is not included.

Electrical Schematics and Air Conditioning

Electrical Circuit Diagrams and Details of Wiring Harnesses support circuit tracing and component identification. The Starter Motor Exploded View shows the internal assembly alongside the engine electrical specifications.

The air-conditioning chapter covers the original R-12 system, including compressor diagnosis, electronic-thermostat checks, actuator adjustment, evacuation, leak testing, and refrigerant charging.

Factory Test Data and Special Tools

The manual lists torque values for both coarse and fine metric threads, plus hydraulic fitting torques, fluid capacities, wear limits, assembly clearances, and electrical test specifications. Model-specific performance tables distinguish standard values from allowable service limits.

Workshop references identify the suction stopper assembly 24100P978F2 and compression-gauge adapter 5-85317-001-0. Dimensioned tool and jig drawings support cylinder and travel-motor work.

Operating instructions and preventive maintenance are referred to the separate Operator’s Manual S2LP1011E. Replacement-part selection is referred to the Parts Manual.

Always consult a certified heavy equipment technician and review proper safety protocols for pressurized hydraulics, raised attachments, and heavy lifting before performing service, testing, or maintenance on these machines.