Description

Komatsu PC300-1, PC300-2, PC300LC-1, N-855-C, NT-855-C 1984 Service Manual

I’ve been wrenching on heavy equipment since before most of you were born. When you’re pulling a head off an N-855-C in a PC300-1 that’s been sitting for three years, you don’t want to guess at torque sequences. That’s why this 1984 Komatsu PC300-1, PC300-2, PC300LC-1, N-855-C, NT-855-C 1984 Service Manual sits in my toolbox. It’s 279 pages of factory procedure, not some reprint from a third party that might have the wrong spec for injector height. Let me walk you through what’s inside and why you need it on your bench.

What This 279-Page Manual Covers

The table of contents breaks into seven main sections: 01 General, 11 Structure and Function, 12 Testing and Adjusting, 13 Disassembly and Assembly, 14 Maintenance Standard, 15 Repair and Replacement, and 19 Others. Each section is packed with the kind of detail you’d expect from a shop manual that was meant for dealer technicians. Section 11 alone runs from page 11-001 through 11-064, covering the engine body, intake and exhaust system, turbocharger, after-cooler, lubrication system, fuel system, cooling system, electrical system, and accessory air compressor. Need to understand the camshaft and valve timing? That’s in the engine body part of section 11, right after the cylinder block and main circulation system.

Engine Body: Cylinder Head, Valve System, and Camshaft

Section 11 dives deep into the cylinder head, valve system, and camshaft. It shows you the exact layout of the valve train, including the crosshead and crosshead guide, rocker lever and shaft. If you’re rebuilding a PC300LC-1 head, you need the valve clearance adjustment procedure from section 12 – that’s page 12-001 specifically. Section 14 gives you the maintenance standard for the camshaft, cam follower, and push rod, including wear limits. Page 14-032 for camshaft journal clearance limits. Don’t trust a generic Cummins book for that; Komatsu calls out specific numbers for their application.

Fuel System and PT Pump – Critical Adjustments

The fuel system chapter in section 11 covers the PT fuel pump, PT fuel pump drive, injector, fuel filter, water separator, and aneroid control valve. Section 12 gives you the PT pump calibration data, PT fuel pump parts specification, and injector specification. If you’re chasing a stumble at high idle on an NT-855-C in a PC300-2, you’ll use the “Measuring Fuel Pressure” procedure and the “Testing and Adjusting Data” tables. The manual includes a full testing and adjusting tool list – you will need those special tools, so get them before you start. Aftermarket manuals skip these tool lists. I’ve seen too many guys ruin a PT pump because they used a gauge that flows wrong.

Testing and Adjusting – Injector and Valve Clearance, Compression Pressure

Section 12 is where you live when you’re diagnosing a smoking engine. It walks through testing and adjusting injector and valve clearance, measuring compression pressure, blow-by pressure, oil consumption, and fuel pressure. There’s also a run-in standard and performance test criteria. The troubleshooting tables at the end of section 12 are worth the price alone – they list symptoms, probable causes, and corrective actions. For example, if your PC300-1 has low power, the manual tells you to check the aneroid control valve and the turbocharger wastegate. Page 12-045 has the compression pressure specs for both the N-855-C and NT-855-C. Do not rely on internet forum numbers.

Why OEM Beats Aftermarket – Original Komatsu Print

This is a genuine Komatsu shop manual printed in Japan in 1984, not a scanned reprint from a guy who bought a copy off eBay. The revision list on page 00-2-1 shows the mark system for pages that were added or replaced – that’s accountability you never get from an aftermarket PDF. The OEM document includes assembly drawings, performance curves, a weight table, and exploded views that are crisp and to scale. Aftermarket manuals often omit the performance curve data, which you need for hydraulic pump matching on a Komatsu machine. For related engine-specific documentation, see the Komatsu N-855 Series Diesel Engine Workshop Manual – but note that’s a different document focused purely on the engine block itself. If you need the full machine manual for the PC300-2 and PC300LC-2, check Komatsu PC300-2 PC300LC-2 1992 Service Manual. For even larger equipment, Demag Komatsu H 285 S Service Manual – 544 Pages of Factory Specs covers the H 285 S.

Who Needs This Manual

If you own a PC300-1, PC300-2, PC300LC-1, or you’re working on any machine that uses the N-855-C or NT-855-C engine – like the D80A.E-18, D85A.E.P-18, D80F-18, D95S-2, PC400-1, or HD320-2 – you need this manual. It addresses the pain point of wasted billable hours because of wrong torque specs or inaccurate wiring diagrams. The “Structure and Function” section gives you the theory, the “Testing and Adjusting” section gives you the procedure, and the “Repair and Replacement” section gives you the machining limits. If you’re a shop owner, having this on the shelf means your techs stop guessing and start producing. Skip this and you’ll be pulling a head twice because you torqued the cylinder head bolts in the wrong sequence. The manual also applies to the PC300LC-2 – but only the engine portion; the chassis electrical is different. For the drivetrain side, you’ll need a separate Manual Transmission manual. And if you’re working on the manual transmission of the D80F, you’ll want a dedicated Manual Transmission resource.

FAQ

Does this manual cover the PC300LC-2?

It covers the N-855-C and NT-855-C engines as used in the PC300LC-1. For the PC300LC-2, the engine content is the same, but the machine-specific sections are not included. See Komatsu PC300-2 PC300LC-2 1992 Service Manual for that.

What torque values are listed?

The standard tightening torque table is in section 19 OTHERS, page 19-001. Every component-specific torque appears in the appropriate chapter – cylinder head bolts, main bearing caps, flywheel bolts, injector hold-downs. You need the manual open to get them all.

Is this the same as the Cummins N-855 workshop manual?

No. This is the Komatsu application-specific manual. It includes machine mounting details, the PT pump drive as installed, and Komatsu performance curves. A Cummins manual covers the bare engine. If you want a pure engine manual, the Komatsu N-855 Series Diesel Engine Workshop Manual is closer but still a different document. This one is for guys who work on Komatsu iron.

Can I use this for the D80A.E-18 dozer?

Yes, for the engine portion. The NT-855-C in the D80A.E-18 is covered in this manual – the structure, testing, and repair sections apply directly. However, you will not find the chassis wiring or undercarriage specs here. You need the D80A.E-18 machine manual for those. The engine mounts and cooling package may differ, so cross-reference with your machine’s parts book. The manual lists the D80A.E-18 as an applicable machine on the cover page. Use it for engine work, not for transmission or final drive repairs.

Every minute you spend chasing aftermarket data is a minute your machine sits idle. This factory manual puts the Komatsu specifications on your bench – torque sequences, clearance limits, test pressures. Stop trusting forum posts and scanned fragments. Access the Factory Manual and have the right numbers the next time you torque a head bolt on an N-855-C.