Description

Komatsu 155-4 SERIES Workshop Manual

If you’re working on a Komatsu 155-4 SERIES Workshop Manual is what you need to keep that engine running right. I’ve spent 28 years turning wrenches and I’ve seen too many guys grab a generic diesel book and then chase their tails because the valve clearance spec is off by half a thou or the head bolt torque sequence is wrong. This manual is the real thing – 376 pages of Komatsu’s own factory data. No aftermarket guesswork, no reprinted half-truths. You get the same document the dealer techs use.

Specifications for the 155-4 SERIES engine are listed on page 01-006. That includes displacement, firing order, and all the numbers you need to order the right parts. But the real meat is in the sections that follow. Let’s break down what’s inside.

Engine Overhaul Coverage

This manual takes you through the entire engine disassembly and assembly process. Starting with the cylinder head – you’ll find the valve system section that covers the rocker arm, crosshead, and tappet. Each component has a dedicated page with wear limits and inspection checks. The cylinder block section shows you how to measure cylinder liner protrusion and fit the main bearings. The book also covers the balancer shaft and timing gear – critical for getting the cam and crank timing right. I’ve seen engines ruined because someone guessed on the balancer shaft alignment. Don’t be that guy.

What Torque Values Are Listed?

Komatsu gives you torque specs for every fastener that matters. Cylinder head bolts, main bearing cap bolts, connecting rod nuts, and the P.T.O. drive. The torque values are in the Maintenance Standard section (chapter 14) along with acceptable limits for reuse. You won’t find a generic “tighten to spec” here – they list the tightening sequence and the angle after the initial torque. If you’re rebuilding the engine, you need these numbers. A head gasket leak on a loaded machine costs more than this manual.

Cylinder Head and Valve System: Factory Disassembly Procedure

The Valve, Valve Guide, and Crosshead section (chapter 14) gives you the stem-to-guide clearance limits and valve face angle specs. The rocker arm assembly removal is shown step by step in chapter 13. Pay attention to the order – they tell you to loosen the rocker arm adjusting screws before pulling the shaft. That prevents bending the pushrods. I’ve watched a kid snap three pushrods in a row because he skipped that step. The manual won’t let you make that mistake if you follow it.

3 Reasons to Use the Factory Komatsu Manual

1. Correct tolerances for cylinder liner protrusion. The liner height above the block face is critical for head gasket sealing. This manual gives the exact range in thousandths of an inch. A generic manual might give a range that’s too wide or just say “flush to 0.005” – not good enough.
2. Proper fuel injection pump timing specs. The Testing and Adjusting chapter (12) has the procedure for setting injection timing with a dial indicator. The table lists the plunger stroke for each cylinder. Miss that by a degree and the engine smokes, loses power, and wastes fuel.
3. Accurate turbocharger maintenance standards. The turbo section in chapter 14 gives the shaft end play and radial clearance limits for both the KTR100/130 and RH1521 turbos. Overhaul those incorrectly and you’re looking at a runaway engine.

Get the Right Testing and Adjusting Data

The testing section starts on page 12-001 with preparation steps. You’ll need a fuel injection pump test bench for some checks, but the manual also includes engine performance test procedures you can run with the engine in the machine. The tool list at the end of chapter 12 tells you exactly what special tools Komatsu requires – part numbers and all. If you don’t have a fuel injection pump timing tool, they list the Komatsu tool number. That saves you ordering the wrong adapter.

For similar Komatsu equipment manuals, check Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual and Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual. Also available: Komatsu PW95R-2 Workshop Manual – 520 Pages of Factory Specs. If you need to understand manual transmission basics, Manual Transmission has good info. For general manual transmission theory, Manual Transmission.

Frequently Asked Questions

Does this manual cover the fuel injection pump?

Yes, it covers fuel injection pump disassembly and assembly.

What torque values are listed?

Cylinder head bolts, main bearing caps, connecting rods, flywheel bolts, and many more. The Maintenance Standard chapter (14) gives both torque and angle for each fastener. For example, the cylinder head bolts on the 155-4 series have a specific tightening sequence that must be followed – the manual shows it with a diagram. You also get the tightening torque for the oil pump relief valve and the water pump. All values are in foot-pounds or inch-pounds with the correct conversion factors.

Is this a PDF or printed book?

The manual is a digital PDF file – 376 pages, searchable, printable. You can take it to the shop on a tablet or print specific pages.

How do I adjust the fuel injection timing?

The procedure is in chapter 12, Testing and Adjusting. You’ll need a dial indicator and the Komatsu timing tool. The manual gives the plunger stroke for each cylinder and the method to set the injection pump drive gear.

Access the Factory Manual now and keep a copy on your tool box. This isn’t a reprint or a third-party summary – it’s the official Komatsu document with all the step-by-step procedures, labeled diagrams, and factory torque values. You’ll save yourself time and headaches. Get the manual that shows you exactly how the engineers intended the 155-4 SERIES to be serviced. Access the Factory Manual.