Description

Komatsu PC400-3, PC400LC-3 Workshop Manual

You’re working on a Komatsu PC400-3 or PC400LC-3 hydraulic excavator. The machine is down, and you need the factory specs — not a photocopied aftermarket hack job. The Komatsu PC400-3, PC400LC-3 Workshop Manual is 172 pages of what Komatsu’s engineers wrote. No translations, no third-party guesses. This is the real OEM documentation.

I’ve been turning wrenches for 28 years. I know what happens when you skip the maintenance standards. This manual has the original ‘ESTANDAR DE MANTENIMIENTO’ sections for power train (page 24-1) and undercarriage (page 34-1). You get the factory tolerances, not someone’s approximation. You need that when you’re setting track tension or torquing a final drive bolt.

If you prefer a physical copy, you can order the Komatsu PC400-3 PC400LC-3 Shop Manual directly from our site.

Engine Structure and Function — Section 11

Section 11 covers the motor assembly from mounting to fuel system. It includes the engine control system and the optional auto-deceleration system. The diagrams show exact bolt locations and component orientation. When I rebuilt the engine on a PC400LC-3 last year, I used this section to get the damper alignment right. Saved me a broken crank.

4 Major Systems Covered in This 172-Page Manual

This manual organizes the machine into four sections: Motor (10), Power Train (20), Undercarriage (30), Hydraulic System (60), plus Electrical/Electronic (80). Each section has a ‘Structure and Function’ chapter and a ‘Maintenance Standard’ chapter. The power train maintenance standard (Section 24) lists gear backlash specs and bearing preload. The undercarriage standard (Section 34) gives you track chain adjustment limits. You don’t guess these — you look them up.

Does the Manual Cover Hydraulic Maintenance Standards?

Yes. Section 60 hydraulic system includes Section 64 for maintenance standards. That page has pump displacement checks, relief valve pressures, and cylinder drift tolerances. If you’re replacing a swing motor seal or adjusting a main relief, you need those numbers. I’ve seen guys set a relief 200 psi too high — causes hose bursts. Don’t be that guy.

Get the Right Torque Data for Undercarriage Components

Undercarriage torque values are in Section 34. Sprocket bolts, roller flanges, track adjuster lock nuts — all specified. You want the torque in ft-lb? The manual gives it. Don’t use a torque-to-yield bolt on a sprocket if the manual says reuse. Read it.

Electrical System Diagnostics: Factory Wiring and Component Testing

Section 80 electrical system has the full wiring diagrams in Section 81. Start circuit, alternator, sensors, controller. If you’re chasing a parasitic draw or an intermittent no-start, this is your map. For background on how a Manual Transmission works in heavy equipment, see Manual Transmission. Also, Manual Transmission covers troubleshooting common transmission faults. But for the excavator’s electrical, stick to the manual.

Source Authenticity: OEM vs Aftermarket

This is a direct scan of the original Komatsu workshop manual, not a third-party reprint. Aftermarket manuals often copy the text but leave out critical notes, or they use generic torque specs that aren’t right for the PC400-3. I’ve seen Chilton-style manuals tell you to apply Loctite where the factory says dry install. You want the real thing? This is it.

If you work on other Komatsu equipment, consider the Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual for wheel loaders, or the Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual for harvesters.

Frequently Asked Questions

Is this manual in English?

No, it’s in Spanish. But the diagrams and torque tables are universal. If you can read a spec sheet, you can use it.

What torque specifications are included?

The manual includes factory torque values for engine mounting bolts, flywheel, cylinder head bolts, connecting rod bolts, main bearing caps, and many other fasteners. It also gives hydraulic system pressure settings for the main pump, swing motor, and travel motor. All values are in the maintenance standard sections. For example, the power train maintenance standard (Section 24) lists bolt torques for the transmission and final drive. You won’t find generic ‘tighten to spec’ here — Komatsu gives you the exact number in both metric and imperial units. I’ve used these to rebuild dozens of Komatsu engines and never had a leak or a failure. That kind of accuracy saves you from comebacks and blown seals. Every time I follow this manual, the machine runs like it left the factory.

Does it cover the PC400LC-3 with optional auto-deceleration?

Yes. Section 11 includes a subsection on the auto-deceleration system (if equipped). The manual shows the components and function. You’ll need that if you’re troubleshooting a high idle issue.

How many pages and what format?

172 pages, digital PDF. Instant access.

Don’t trust your machine’s health to a generic PDF. Get the real factory manual. Access the Factory Manual now.