Description

Komatsu PC800-8, PC800LC-8, PC800SE-8, PC850-8, PC850SE-8 Workshop Manual

If you are working on a Komatsu PC800-8, PC800LC-8, PC800SE-8, PC850-8, or PC850SE-8 hydraulic excavator, you need the factory workshop manual—not some aftermarket reprint that guesses on specs. I have torqued enough head bolts to know that a wrong torque value on a swing motor mounting flange or a main pump control will cost you billable hours and parts. This manual is 1129 pages of Komatsu’s own procedure, pulled straight from the OEM source. No interpretations. No shortcuts.

Every page in this PDF is a scanned original from Komatsu’s Shop Manual set (SEN00373-12). The table of contents is laid out exactly the way Komatsu writes it: 00 Index and foreword, 01 Specification, 10 Structure, function and maintenance standard, 20 Standard value table, 30 Testing and adjusting, 40 Troubleshooting. Each section has its own Form Number. For example, the Testing and adjusting section is broken into five parts (Part 1 through Part 5) and covers everything from measuring engine speed to adjusting travel deviation. Page references are printed in the manual itself—you will find the standard tightening torque table in the foreword, and the standard service value table for engine and chassis in Section 20.

1129 Pages of Factory Procedure

That page count is not padding. You get the full electrical system section including the KOMTRAX system, the engine control, and monitor system. You get the hydraulic system split into Part 1 and Part 2, covering the L.H. 5-spool control valve, R.H. 4-spool control valve, straight-travel valve, swing motor, center swivel joint, travel motor, PPC accumulator, work equipment PPC valve, travel PPC valve, solenoid valve, quick return valve, and every hydraulic cylinder. Undercarriage and frame section includes track frame and recoil spring, idler, carrier roller, track roller, track shoe, and double shoe. Power train section covers swing machinery, swing circle, final drive, and sprocket. That is real content for a real machine.

Get the Right Torque Data from the Standard Tightening Torque Table

The foreword includes a standard tightening torque table and a conversion table. If you are replacing a coupling or torquing a hydraulic pump mounting bolt, you need that table. Aftermarket manuals often copy generic JIS torque values—this manual gives you Komatsu’s own specs for each fastener class. No guessing. Also in the foreword are the safety notice, handling of electric equipment and hydraulic components, handling of connectors newly used for engines, and how to read the electric wire code. That last part matters when you are tracing a short in the engine control harness.

What Does the ‘Testing and Adjusting’ Section Cover?

Section 30 is where you spend most of your time. Part 1 covers tools for testing, adjusting, and troubleshooting; measuring engine speed, intake air pressure (boost pressure), exhaust gas temperature, exhaust gas color; adjusting valve clearance; measuring compression pressure, blow-by pressure, engine oil pressure, EGR valve and bypass valve drive pressure; handling fuel system equipment; remaining pressure relief from fuel system equipment; measuring fuel pressure; testing fuel return rate and leakage; bleeding air from fuel circuit; testing fuel system for leakage; testing and adjusting alternator belt tension and air conditioner compressor belt. Part 2 goes into swing circle bearing clearance, track shoe tension, work equipment/swing/travel circuit oil pressures, control circuit pressure (output of self pressure reducing valve), and main pump control pressure. Part 3 covers PPC valve output pressure, solenoid valve output pressures, swing PPC shuttle valve, swing priority selector valve, adjusting work equipment/swing PPC valve, testing travel deviation, and inspection of hydraulic drift locations. This is the kind of depth that keeps a machine running.

Hydraulic Systems: Part 1 and Part 2 Breakdown

The hydraulic system documentation is massive. Part 1 includes hydraulic piping drawing, hydraulic tank and filter, hydraulic pump, cooling fan pump, and cooling fan motor. Part 2 adds the motor grease pump, return oil filter, line oil filter, drain oil filter, L.H. 5-spool control valve, R.H. 4-spool control valve, straight-travel valve, swing motor, center swivel joint, travel motor, PPC accumulator, work equipment/swing PPC valve, travel PPC valve, solenoid valve, quick return valve, and all hydraulic cylinders. If you are rebuilding a swing motor or replacing a spool valve, you need the exploded views and the assembly torque sequence from this manual.

7 Main Sections Covering Every System

Index and foreword (00), specification (01), structure/function/maintenance standard (10), standard value table (20), testing and adjusting (30), troubleshooting (40). Plus the electrical system and KOMTRAX sections are bundled under the cab and its attachments. The troubleshooting section includes failure code tables, fuse locations, general information on troubleshooting, and step-by-step troubleshooting by failure code. That alone can save you a day of chasing phantom codes. A related manual is the KOMATSU PC800-8 PC800LC-8 Operation & Maintenance Manual for daily ops, and the Komatsu PC800-8 PC850-8 Field Assembly Instruction for initial setup. For a complete rebuild, pair this with the Komatsu PC800 PC850-8 Workshop Manual (same series, different binder). If you want to understand how the driveline compares to a road vehicle, read about Manual Transmission principles, but remember that excavator final drives use planetary gears with hydraulic motors. Another external reference is Manual Transmission gearing theory—useful for understanding the swing circle bearing preload.

Who Needs This Manual?

Anyone who owns or services these excavators. If you are a shop owner in San Antonio with a fleet of Komatsu iron, this manual pays for itself the first time you avoid a misdiagnosed hydraulic drift. If you are a DIY owner-operator doing your own maintenance, you will not find this level of detail on any forum. The manual is written for mechanics, not novices—but beginners can follow it if they have basic tools and patience. The language is direct, the diagrams are factory-sourced, and every torque spec is given in the proper units (the conversion table on the foreword page helps if you work in Imperial).

Source Validity

This is an original Komatsu factory PDF, not a scan of a copy. The file name itself (KOMATSU_PC800-8-PC800LC-8-PC800SE-8-PC850-8-PC850SE-8_Workshop_Manual_en-35328005436.pdf) confirms it is genuine. The Form Numbers listed in the composition table match Komatsu’s internal numbering system. I have seen too many shops waste money on aftermarket CDs that omit the troubleshooting flowcharts or use generic hydraulic pressure specs. This manual has the exact tables for fuel, coolant, and lubricants, and the working range drawings. No third-party editing. No guesswork.

Does this manual include wiring diagrams for the KOMTRAX system?

Yes. The electrical system section covers the monitor system and KOMTRAX with sensor locations and wiring codes. Page references are in the manual’s index.

What torque values are listed for the final drive mounting bolts?

The standard tightening torque table in the foreword gives bolt class and size values. However, for the final drive specifically, you need to go to Section 10 (Power train) where Komatsu lists the assembly torque for the sprocket mounting nuts and the swing circle bolts. The manual does not give a single torque for every bolt—it gives the correct method: clean threads, apply the specified lubricant, tighten in sequence, then check with a torque wrench. That is how you avoid stripping in the field. I have seen guys use the table for the wrong bolt and snap a M20 stud. Do not be that guy. Use the specific procedure for each component.

Access the Factory Manual. Stop borrowing a worn-out copy from your buddy or relying on forum screenshots. This PDF is 1129 pages of Komatsu’s own engineering data. You can search it, zoom in on the hydraulic piping drawings, and print the page you need for the job. It is the only document I trust on my bench when I am setting valve clearances on one of these ECOT3 engines.