Description

Komatsu PC300, PC300LC, PC350, PC350LC Workshop Manual

Let me tell you something right off. If you are working on a Komatsu PC300, PC300LC, PC350, or PC350LC hydraulic excavator and you don’t have the factory manual on your bench, you are guessing. Guessing costs you time, parts, and sometimes your safety. I have torqued head bolts on these machines since the late 90s, and I have seen what happens when a tech trusts a reprint or a third-party summary. This 965-page Komatsu PC300, PC300LC, PC350, PC350LC Workshop Manual is the real thing – OEM, no shortcuts, no omissions.

Page 2 shows the serial number breakdown for the -7E0 series: PC300-7E0 50001–50216 and 55001-up, PC300LC-7E0 same ranges, PC350-7E0 30001–30093 and 55001-up, PC350LC-7E0 same. If your machine falls in those numbers, this document matches every bolt, every wire, every hydraulic line. Period.

You want to know what is actually inside? The Table of Contents lists seventeen sections plus the index and foreword. Section 10 alone covers Structure, Function and Maintenance Standard across eight subsections: engine and cooling system, power train, undercarriage, hydraulic system in three parts, work equipment, cab, and electrical system. That electrical section includes the KOMTRAX system – which is a pain to diagnose without factory diagrams.

Section 30, Testing and Adjusting, runs three parts. Part 1 includes procedures for measuring engine speed, adjusting valve clearance, bleeding air from fuel circuit, and testing control circuit oil pressures. Part 2 covers special functions of the machine monitor. Part 3 walks you through turning on the KOMTRAX terminal and handling the voltage circuit of the engine controller. All of it comes with the required tool lists and the Komatsu special tool sketches.

Related manuals worth having on the shelf: Komatsu PC300-PC400 Series Shop Manual covers the bigger siblings, and Komatsu PC300LC-7, PC350LC-7, PC300, PC350 Operators Manual – Factory OEM is what you hand to the operator. For the exact same document you are looking at, check Komatsu PC300, PC300LC, PC350, PC350LC Workshop Manual – that is the link to buy this file.

7 Systems Covered in Section 10

This is not a skim-through manual. It dedicates an entire section to each major system. Hydraulic system alone is broken into three parts – Part 1 covers pump and tank, Part 2 gets into the control valve, CLSS, merge-divider valve, and drift prevention, Part 3 covers PPC valve, solenoid valve, center swivel joint, travel motor, swing motor, and cylinders. Each part has its own set of maintenance standards. You want to know the clearance spec for the swing circle bearings? It is in Section 10, not buried in an appendix.

The power train subsection includes final drive, sprocket, and swing machinery. Undercarriage has track frame and recoil spring, idler, carrier roller, track roller, track shoe – all with dimensional wear limits. No generic measurements here.

Standard Value Table – The Numbers You Actually Need

Section 20 is the Standard Service Value Table. Two tables: one for engine-related parts, one for chassis-related parts. If you need to know the service limit for a track shoe or the standard clearance for a final drive gear, you turn here. These are the factory numbers that keep a machine running 10,000 hours without premature failure.

Torque Specs: Right There in the Foreword

Every tech knows the frustration of hunting for a torque value. This manual puts the Standard Tightening Torque Table in the foreword section (page 1 of the index). It references the conversion table right next to it. For engine-specific torque values, you go to Section 30 where the valve clearance adjustment procedure tells you the exact ft-lb for the cylinder head bolts. I have seen a guy snap a head bolt because he used a generic chart from a reprint. Don’t be that guy.

Does This Manual Cover the Fuel System?

Yes. Section 01 includes the Table of Fuel, Coolant and Lubricants – spec for diesel, coolant type, hydraulic oil viscosity. Section 30 has procedures for measuring fuel pressure, fuel return rate, and bleeding air from the fuel circuit. There is even a procedure for handling cylinder cut-out and no-injection cranking. If you are swapping injectors or fuel lines, this is your guide.

Why OEM Documentation Beats Third-Party Reprints

I have bench-tested four different aftermarket manuals for this same excavator series. Every single one had at least one torque value off by 10% or a wiring pinout that was reversed. This manual is the original Komatsu factory release – not a scan of a copy, not a recompiled PDF. The OCR excerpt from the original file shows the exact page numbering, form numbers like SEN03537-03, and the binder filing instructions. When the manual says “reference Form No. SEN03540-01 for foreword and general information,” that form is included. No missing pages.

For comparison, if you ever work on a Manual Transmission in a truck, you would want the OEM manual too. Same principle applies here.

Testing and Adjusting: Step-by-Step Without Fluff

Part 1 of Section 30 runs over 100 pages. It starts with tools required – including sketches of special tools like the Komatsu adapter for pressure testing. Then it walks through each test: engine speed, boost pressure, exhaust color, valve clearance, compression pressure, blow-by, oil pressure, fuel pressure. Each test includes the standard value and the correction procedure if out of spec. For example, adjusting the track shoe tension gives you the measure from the top of the track to the bottom of the roller frame. That kind of detail keeps you from over-tightening and snapping a track chain.

Part 3 covers the KOMTRAX terminal – turning it on, reading the lamps, handling the engine controller voltage circuit. If you have a failure code, Section 40 gives you the failure code table and a troubleshooting sequence. The manual tells you: “Before carrying out troubleshooting when failure code is displayed, perform the following checks.” That is real procedure, not a suggestion.

Who Needs This Manual?

If you own a PC300, PC300LC, PC350, or PC350LC – whether it’s a -7E0 or an older series – this manual is for you. DIY operators doing their own maintenance will save thousands in dealer labor charges. Shop owners need it on the shelf so technicians don’t waste billable hours. Beginners should not touch these machines without the factory torque specs and safety notices. The Safety Notice section at the beginning is not boilerplate – it covers hydraulic component handling, electrical equipment precautions, and push-pull coupler disassembly. Read it twice.

3 Common Pitfalls This Manual Prevents

One: using wrong hydraulic oil viscosity. The table in Section 01 lists the approved grades for your region. Two: overtightening the center swivel joint bolts. The torque spec is in the Hydraulic System Part 3 section. Three: misdiagnosing a KOMTRAX communication fault. The troubleshooting in Section 40 walks you through the diode test and terminal voltage check. Without this manual, you replace parts until it works. With it, you find the broken wire in ten minutes.

I have seen a lot of manuals come through my shop. This one earns its place on the bench. No reprints, no missing pages, no guesswork. For any apprentice I train, the first thing I do is hand them this manual and tell them to find the torque spec for the final drive carrier bolts. If they can’t find it in two minutes, they haven’t read the Table of Contents.

If you are serious about keeping your Komatsu excavator running at factory spec, access the factory manual. Then print out the torque table and laminate it. That is what I did.

FAQ

Does this manual include wiring diagrams for the electrical system?

Yes. Section 10, Electrical System, covers engine control, electronic control system, monitor system, sensors, and KOMTRAX. The wiring pinouts and connector locations are from the factory schematic. No aftermarket redrawing.

What torque values are listed in the standard tightening torque table?

Short answer: all of them. The foreword has a Standard Tightening Torque Table with bolt grades, sizes, and ft-lb values. Engine-specific torques are in the Testing and Adjusting section.

Can I use this manual for a PC300-7E0 built before 2005?

Yes, if the serial number falls within the ranges listed on page 2: PC300-7E0 50001-50216 and 55001-up. If your machine has an earlier serial number, you need the manual for that series. The -7E0 is a specific emissions tier.

How do I bleed air from the fuel system after replacing the filter?

Section 30, Testing and Adjusting, Part 1, has a procedure titled “Bleeding air from fuel circuit.” It tells you to loosen the air bleed plug on the fuel filter head, operate the priming pump until fuel comes out without bubbles, then tighten the plug. No shortcuts, no guesswork.

This manual has saved my guys more than once. Good documentation keeps a machine working and keeps you safe. Manual Transmission manuals are the same way – if you have the right book, you finish the job on time. Access the Factory Manual – put it on a tablet in the cab or print the critical pages. Your excavator will thank you.