Komatsu PC300LC-6, PC300-6, PC350-6, PC350LC-6 2002 Workshop Manual

If you are turning wrenches on a Komatsu PC300LC-6 or any of the -6 series machines—PC300-6, PC350-6, PC350LC-6—you need the factory book, not some third-party reprint that guesses at torque values. I have seen too many guys snap head bolts because they trusted an aftermarket PDF that listed 50 ft-lbs instead of 80. That mistake costs you an engine rebuild and three days of downtime. This Komatsu PC300LC-6, PC300-6, PC350-6, PC350LC-6 2002 Workshop Manual is the exact document Komatsu issued in 2002. It runs 809 pages and covers every system from the SAA6D108-2 engine to the CLSS hydraulic circuitry. You want fuel specs? They are in section 01. Torque? The Standard Tightening Torque chart is in the Foreword. Don’t guess—use the OEM source.

Why This Manual Matters for Your Komatsu PC350-6

Every year I see a machine come into my shop with a blown final drive because someone used the wrong oil weight or skipped the final drive oil level check. The manual has a full Fuel, Coolant and Lubricants table on page 01-13. It tells you exactly what viscosity to run in San Antonio summers versus a Minnesota winter. The OEM also includes the weight table for each model variant—PC300LC-6, PC300-6, PC350-6, PC350LC-6—so you know your lifting capacity limits without guessing. If you rely on generic specs, you are risking a $2,000 fluid change mistake.

Torque Specs: Where to Find Them

The Foreword section contains the Standard Tightening Torque table. That is where you look before you tighten anything on the engine or hydraulic system. The manual gives torque values in ft-lbs and also includes the electric wire code for routing—you do not want to cross a wire because you missed a pin number. I have a rule: never touch a bolt on a Komatsu without first checking the standard torque chart in this book. It is printed on the original paper, not scanned from a copy of a copy. That matters when the spec is 125 ft-lbs versus 135 ft-lbs.

7 Systems Covered in the Structure and Function Section

Section 10—Structure and Function—dives into the parts that make the -6 series tick. You get hydraulic circuit diagrams, the control valve layout, the self-reducing pressure valve, the LS-EPC valve, and the boom holding valve. Each subsystem has its own subsection. Need to understand the PPC accumulator function? It is in there. The electrical circuit diagram for the engine control and the machine monitor system is also in section 10. If your monitor panel is throwing a code, you go to the electronic control system chapter and cross-reference the service code table in section 20. I have used the troubleshooting charts on page 20-201 to diagnose a governor pump controller issue in less than an hour—without that page, you are chasing ghosts.

Get the Fuel Specifications Right

Fuel injection timing adjustments are in the Testing and Adjusting section (20). The book tells you the exact procedure to measure compression pressure, blow-by pressure, and adjust the valve clearance. It also covers the Fuel injection timing—a step that many DIYers skip because generic manuals say “turn the pump until it feels right.” That is how you wipe out a cylinder. The Komatsu manual gives you the measurement in degrees and the tool part numbers you need. If you are working on a PC350-6, the engine is the same SAA6D108-2, so these procedures cross directly. You also get the standard value tables for engine, chassis, and electrical parts—all in one volume.

Testing and Adjusting: The Factory Procedure

Section 20 is the thickest part of the manual—over 200 pages of testing, adjusting, and troubleshooting. It starts with a tool list, then walks you through measuring engine speed, exhaust color, and oil pressure. The blow-by pressure check is critical for diagnosing ring wear. I use the testing and adjusting procedure for the hydraulic pressure in the work equipment, swing, and travel circuits every time I repack a cylinder. The book even includes how to release remaining pressure from the hydraulic circuit before you crack a line—safety step that aftermarket books often skip. Combine that with the troubleshooting sequence that starts with “Points to Remember” and the service code table, and you have a diagnostic system that works.

Source Authenticity: OEM vs Aftermarket Documentation

This is the original Komatsu publication, printed in Japan in 2002. The part number SEBM014307 tells you it came from the factory. I do not trust aftermarket manuals that combine data from different model years because Komatsu changed the PC300-6 wiring in later serial numbers. This manual covers serial numbers 33001 and up for PC300-6 and PC300LC-6, and 12001 and up for PC350-6 and PC350LC-6. The electric circuit diagrams are model-specific, not generic. If you have a copy that says “for Komatsu PC300 series” without the -6 suffix, you are missing the hydraulic pump adjustment specs that only apply to the -6 control valve. Do not take shortcuts—use the right manual.

For related documentation, check out the Komatsu PC300LC-6 PC300HD-6 1996 Service Manual for earlier variants, or the Komatsu PC300LC-6 PC300HD-6 1999 Workshop Manual if your machine falls in that range. The Komatsu PC300-6 PC350-6 2002 Workshop Manual is the same base manual as this one, but always verify the serial number coverage. If you want to understand the fundamentals of a Manual Transmission system, that is separate, but for the Komatsu final drive, stick to this book. For general knowledge on hydraulics, a Manual Transmission article will not help you—stay focused on the factory data.

Frequently Asked Questions

Does this manual cover the SAA6D108-2 engine in full?

Yes. The manual includes the engine-related standard value tables, valve clearance adjustment, compression pressure measurement, fuel injection timing, and governor control system troubleshooting. For deeper engine internal specs, Komatsu recommends the separate 108-2 series engine shop manual, but this covers all field service and testing procedures.

Is the wiring diagram color-coded?

The electric circuit diagram is monochrome but uses wire code labels per the Electric Wire Code table in the Foreword. You get pin numbers and connector locations. No aftermarket book I have seen matches the accuracy of the OEM connector arrangement diagrams.

What torque values are listed?

The Standard Tightening Torque chart in the Foreword gives general torque for bolts and nuts. Additional specific torques appear in the disassembly and assembly sections (section 30). The manual does not list every single fastener torque in one place—you must cross-reference.

Can I use this for a PC350LC-6 with serial number below 12001?

This manual covers PC350-6 and PC350LC-6 from serial number 12001 and up. For earlier machines, you need the previous edition. Using this manual on a lower serial number may have differences in the electronic control system and wiring.

Download the Factory Manual and keep it in your toolbox or on your tablet. I keep a printed copy at my shop because the PDF is searchable, but the hard copy never crashes. When you have a PC300LC-6 on the lift and the customer is waiting, having the correct fuel injection timing and torque specs saves your reputation. This is the book that tells you what Komatsu says—not what some forum user thinks. Get the OEM source and work by the book.