Description

Komatsu PC300-7EO, PC300LC-7EO, PC350-7EO, PC350LC-7EO Workshop Manual

You’ve got a PC350-7EO losing pressure on the boom circuit, the aftermarket PDF says “check the control valve” but doesn’t tell you which ports to test or what the CLSS relief should be. I’ve spent more hours than I want to count chasing phantom leaks because some third-party manual skipped the critical details. The Komatsu PC300-7EO, PC300LC-7EO, PC350-7EO, PC350LC-7EO Workshop Manual is the factory-issued book that gives you the full hydraulic theory, the exact test ports, and the step-by-step sequence. No shortcuts, no generic diagrams – this is what Komatsu puts on the dealer tech’s bench.

Hydraulic System: CLSS and Control Valve Breakdown

Section 10, Sistema hidráulico, Parte 2 breaks down the CLSS (Closed‑Center Load‑Sensing System) and the main control valve. You get the function of each spool, the valve‑by‑valve operation of the unión‑división (diverter) and the selector valve for attachments. Komatsu includes the PPC valve, solenoid valves, and accumulator specs. Need the charge pressure for the travel motor? The manual tells you which port on the motor de marcha to tee into and what pressure you should see – not a range pulled from a forum post. The factory standard torque table (in the preface) lists fastener torques in ft‑lbf for common bolts, so you aren’t guessing when you button up the pump drive.

Engine and Cooling System: Factory Maintenance Standards

The engine section covers the related components, the radiator, oil cooler, and post‑cooler. You’ll find the cooling system flow path and the maintenance standards for belt tension and coolant capacity. The manual gives you the spec for checking the fan drive and the torque for the mounting bolts. It’s the same data the Komatsu dealer uses. Water pump replacement? Page 26 (major procedure) lists the bolt torque pattern and sequence. I’ve seen too many shops wreck a water pump housing by tightening in the wrong order – the factory book keeps you from being that guy.

Do You Need 778 Pages of Factory Documentation?

Yes, because every one of those pages has a specific procedure, diagram, or table that you won’t find in a condensed reprint. The book covers four models: PC300‑7EO, PC300LC‑7EO, PC350‑7EO, and PC350LC‑7EO, with serial number breaks (50001 and up for the 300 series, 30001 and up for the 350 series). The TOC includes test and adjustment procedures for measuring engine speed, boost pressure, compression, and hydraulic circuit pressures. That’s not fluff – that’s the difference between a repair that holds and a comeback job. I’ve worked on enough Komatsu iron to know that when the LC (long undercarriage) model has different track tension specs, the factory manual is the only place you’ll find that distinction.

Testing and Adjusting: Valve Lash, Compression, and Hydraulic Pressures

Section 30, Pruebas y Ajustes, is where the manual earns its keep. It lists required tools – everything from a digital tachometer for measuring engine speed to a pressure gauge set for the hydraulic circuits. The step‑by‑step for adjusting valve lash includes the cold clearance in inches (or mm if you prefer, but the manual gives both). Compression test procedure tells you the minimum pressure per cylinder and how to interpret wet vs. dry readings. For hydraulics, you get the test ports for the pump, control, and LS pressures. The manual says to use a 0–6000 psi gauge for the main circuit – not a guess, a spec. Aftermarket manuals love to skip these tool lists, which leaves you scrambling to find the right adapter at 9 PM on a Saturday.

Torque Specifications: The Factory Table

Inside the preface there’s a standard torque table for metric fasteners (class 8.8, 10.9, 12.9) with values in ft‑lbf and N·m. That table covers the bolts you’ll find on the final drive, track frame, and hydraulic cylinder mounts. But for critical joints like the swing circle bolts, the manual gives a separate torque value in the specific section. Page 26 (again, the major procedure) has the swing circle bolt tightening sequence. If you skip the pattern, you’ll get uneven preload and a wobbly house. I’ve seen it happen.

Electrical System: KOMTRAX and Sensor Diagnostics

Section 10, Sistema Eléctrico, covers the engine control, electronic control system, monitor, sensors, and the KOMTRAX terminal. Wiring diagrams are included with wire color codes and connector pin‑outs. The manual explains how to read the wire codes (Forma de leer el código de alambres eléctricos) – something that’s specific to Komatsu harnesses. If you’re chasing a no‑start or an error code, the diagnostic flowcharts in this section will save you from swapping parts. The power train section includes the final drive and drive sprocket, which function similarly to a Manual Transmission in load handling. Understanding the gear reduction in the travel motor requires knowledge of Manual Transmission principles, and the manual provides the gear ratios and backlash specs.

Is this manual in English?

No, it’s the original Komatsu factory manual in Spanish.

Does this cover both the PC300‑7EO and PC350‑7EO series?

Yes, it covers all four models: PC300‑7EO, PC300LC‑7EO, PC350‑7EO, and PC350LC‑7EO with the specific serial number ranges listed. The content is organized by system, so you use the same procedures for the 300 and 350 variations. Track tension, cylinder sizes, and some hydraulic pressures differ between models – the manual notes those differences in the specification tables and the standard value section (Section 20).

Are wiring diagrams included?

Yes, the electrical system section (Sistema Eléctrico) includes full schematics, wire color codes, and connector views. The KOMTRAX system is also documented.

Can I buy a printed paper copy from this site?

AutoRepairManuals sells the PDF format. You can print it yourself or keep it on a tablet in the shop. The file is searchable and bookmarked with the same section structure as the paper manual.

If you need to fix these machines without losing time to guesswork, get the real data. Access the Factory Manual from AutoRepairManuals and put the right numbers on your wrench.

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