Description

Komatsu PC120-3, PC100-3, PC100L-3, PC120-3K, PC150HD-3K Workshop Manual – 629 Pages of Factory Specs

I have seen too many techs crack cylinder heads because they used aftermarket torque specs. If you are working on a Komatsu PC120-3, PC100-3, PC100L-3, PC120-3K, or PC150HD-3K Workshop Manual is the only source I trust for the factory torque values. This is a 629-page OEM document, not a scanned-by-someone-in-a-basement copy. It covers the Engine, Fuel system, valve adjustments, and the entire power train. You skip steps at your own risk.

What the Komatsu PC120-3, PC100-3, PC100L-3, PC120-3K, PC150HD-3K Workshop Manual Covers

Section 10 ENGINE is where you will spend most of your time. It breaks down structure and function – engine mount, PTO, radiator, fuel tank and piping, engine control, and the auto-deceleration system (if equipped). The testing and adjusting subsection (12) includes valve clearance adjustment, measuring compression pressure, fuel injection timing, fan belt tension, blow-by pressure, and exhaust gas color. Page numbers in the manual are clearly marked – look for page 12-1 for the testing and adjusting data table. The disassembly and assembly section (13) walks you through every mounted component: starting motor, alternator, fuel injection pump, engine oil cooler, water pump, nozzle holder, cylinder head, hydraulic oil cooler, radiator, engine, PTO, and deceleration cylinder.

Engine Overhaul Coverage: From Valve Clearance to Cylinder Head

If you are pulling the cylinder head, you need the exact bolt torque sequence and final angular tightening value. None of that generic “tighten to 80 ft-lb” garbage. The manual specifies each step for mounting the cylinder head. It also covers the valve clearance adjustment – intake and exhaust – for the Komatsu diesel engine used in these models. The fuel injection pump timing procedure is detailed with the required special tools listed in the testing and adjusting tool list. Do not attempt a fuel system rebuild without this document.

How to Use the Testing and Adjusting Data

Section 12 gives you a data table that lists acceptable ranges for compression pressure, blow-by pressure, valve clearance, and fan belt deflection. The decelerator speed test and adjustment is also included. Every measurement has a corresponding testing and adjusting tool list – you will know exactly what gauge or adapter you need. For example, adjusting the valve clearance requires a feeler gauge set and a specific wrench. No guesswork. I have used this section to diagnose low power on a PC120-3 and found the fuel injection timing was off by 2 degrees.

629 Pages of OEM Factory Specs

The manual is 629 pages thick. That covers the engine, power train (section 20 – includes travel motor, swing motor, center swivel joint, sprocket), undercarriage (section 30 – track frame, recoil spring, idler, rollers, track shoe), hydraulic system (section 60 – full circuit diagrams and schematics for wrist control and long lever control types), work equipment (section 70), electrical system (section 80 – structure, function, testing), and others (section 90). Each section has its own maintenance standard tables with wear limits and clearance specs. Compare that to the flimsy 100-page aftermarket booklets that skip the swing circle disassembly and assembly procedure.

Fuel Injection Timing and Blow-By Pressure – Factory Procedures

The fuel system chapter in section 13 covers the fuel injection pump dismounting and mounting, as well as the nozzle holder. The testing section gives you the fuel injection timing test procedure and the blow-by pressure test. Blow-by pressure measurement is critical for detecting worn rings or cylinder glazing. The manual tells you the acceptable pressure at a specific engine speed and temperature. I have used this on a PC100L-3 that was smoking – the blow-by pressure was above spec, so we pulled the head and found a broken ring.

Get the Right Torque Values – Don’t Guess

Torque values are scattered throughout the manual where each component is mounted. The cylinder head torque sequence is on the cylinder head mounting page. The swing motor mounting bolts have a different spec. The travel motor bolts, idler assembly, everything. Using the wrong torque on a swing circle bolt can lead to cracking. I have torqued more head bolts than most people have had hot meals, and I still check the manual every time for these older Komatsu models because the spec changed between serial number breaks. Trust the factory data, not memory.

Related manuals you might need:
– Komatsu PC100 PC120-3 Service Manual
– Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual
– Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual

If you need background on how a manual transmission works in an excavator’s power train, Wikipedia has a decent overview – but for the Komatsu, you need the factory hydraulic circuit diagrams. Another external resource is the manual transmission article for general knowledge, but again, for the specific travel motor and center swivel joint, stick with the OEM manual.

FAQ

Does this manual cover the auto-deceleration system?

Yes.

What torque values are given for the cylinder head bolts?

The manual provides the exact OEM torque sequence and final tightening angle for the cylinder head bolts on the engine used in PC100-3, PC120-3, PC100L-3, PC120-3K, and PC150HD-3K. It is located in the cylinder head mounting procedure within section 13. The values depend on the bolt grade and include a multi-step tightening pattern. Do not use generic torque specs – they will fail. This manual also includes the required special tools for torquing the head bolts, such as an angle gauge or torque wrench with degree markings. I have had to re-torque heads on these machines because someone used a standard bolt chart instead of the factory spec. Save yourself the comeback.

Stop risking expensive components with second-hand data. Get the factory document that Komatsu technicians used. Access the Factory Manual now.