1989–1994 Komatsu PC10-7, PC15-3, PC20-7 Mini Excavator Shop Manual (SEBM020P0703)

This Komatsu shop manual, SEBM020P0703, covers mechanical, electrical, and hydraulic repair for the 1989–1994 PC10-7, PC15-3, and PC20-7 mini excavators within the serial ranges listed above.

Text search, navigation, and diagram detail: PDF text search is unavailable. Embedded bookmarks navigate the main sections and individual procedures. Small wire codes and connector numbers in the wide electrical diagrams require zooming.

• Engine service: Cylinder-head and engine removal and installation, valve-clearance adjustment, compression testing, fuel injection timing, and fuel control lever adjustment.

• Hydraulic repair: Circuit pressure testing, work equipment drift diagnosis, control valve disassembly and assembly, hydraulic cylinder repair, and air bleeding.

• Travel and swing: Power train layouts, motor and final drive troubleshooting, component cross-section views, and model-specific motor and reduction gear repair procedures.

• Undercarriage and work equipment: Track frame, recoil spring, idler, and roller service, plus boom, arm, bucket, and blade removal and installation.

• Electrical and monitor systems: Wiring diagrams, engine shutdown fault tracing, connector locations and connection tables, and monitor panel troubleshooting.

• Service reference data: Standard judgment values, fluid capacities, wear limits, electrical test specifications, and tightening torque tables for bolts, nuts, and split flange hardware.

Written for workshop service personnel, this manual assumes access to lifting equipment, hydraulic test instruments, and the specified assembly tools.

Engine Service and Overhaul Limits

The engine sections distinguish the PC10-7's 3D78N-1B from the PC15-3's 3D84N-2K and PC20-7's 3D84N-2H. Separate procedures address cylinder-head installation, water pumps, and thermostats, with additional removal and installation instructions for the injection pump, nozzle holders, front and rear engine seals, radiator, and oil cooler.

Engine scope: Further engine detail is referred to the separate 78 Series and 84 Series Engine Shop Manuals. Those volumes are not included in this PDF.

Hydraulic Drift and Control Valve Repair

The work equipment drift test helps distinguish cylinder packing leakage from a control valve fault before choosing the repair. Model-specific hydraulic circuit diagrams show pump routing and relief settings, while valve control drawings connect the operating levers to their spools.

Both 7-spool and 2-spool control valve assemblies have disassembly and assembly coverage. The PC10-7's 2-spool valve includes a safety-suction valve arrangement absent from the PC15-3/PC20-7 version.

Air-bleeding instructions cover hydraulic cylinders and travel motors; the swing-motor bleeding procedure applies to PC15-3/PC20-7. Hydraulic pump coverage includes removal, installation, construction details, and delivery and clearance standards.

Travel and Swing Repair Coverage

Internal travel motor and final drive disassembly and assembly are labeled for the PC20-7. Swing motor and swing machinery overhaul procedures apply to PC15-3/PC20-7, including shaft end-play and rotating-torque checks. PC10-7 swing-motor removal and installation are covered separately.

The swing-motor rebuild instructions warn that shaft splines can damage the oil seal during shaft removal or installation. Center swivel joint removal, seal replacement, and assembly are also covered.

Undercarriage and Serial-Specific Wear Standards

Steel and rubber shoe specifications have separate carrier roller and track roller data. Recoil spring service identifies the spacer used only with rubber shoes, while swing circle installation drawings show the bearing soft-zone positions.

Work equipment maintenance standards split the PC20-7 at serial 37001, with separate tables for 35001–37000 and 37001 and up. The arm, bucket, and linkage pin-and-bushing dimensions differ across that break.

Electrical Diagnosis and Test Equipment

The Engine Stop Motor System and Monitor System circuit diagrams accompany connector-location drawings and mating-pin connection tables. C-, H-, and P-mode troubleshooting charts address engine shutdown failure, hydraulic and mechanical faults, and monitor problems such as incorrect fuel or coolant gauge readings.

The test-tool list identifies hydraulic tester 799-101-5001 and T-adapter kit 799-601-7100. Connector-handling notes explain how twisting a connector out of its retaining clip can break the housing.

Note: Heavy equipment maintenance carries inherent safety risks. Follow the manual's precautions for hydraulic testing, suspended components, and the loaded recoil spring.

PDF Contents and Included Revision Pages

Supplied as one printable English 262-page PDF, including the cover, two revision-list pages, 19 inserted pages within the technical sections, and an older blade-service page numbered 30-81. These pages are already included in the total.