Description

Komatsu 108-2 2009 Workshop Manual

Let me tell you something about aftermarket manuals: they skip half the torque specs and re-draw wiring diagrams until they’re useless. I’ve been a master tech for 28 years, and the first thing I check when a junior tech brings me a job is whether he’s using OEM documentation. This Komatsu 108-2 2009 Workshop Manual is the real deal – printed by Komatsu, 226 pages, with every spec the factory intended. No paraphrased garbage.

Torque Specs: Where Most Repairs Go Wrong

Page 26 (standard tightening torque table) has the numbers you need for every fastener on the engine. Cylinder head bolts? Check. Main bearing cap? Check. Flywheel bolts? Check. The manual gives values in Nm, but there’s a conversion table right in the foreword. I recommend you convert to ft-lb and write them on the cover. Aftermarket manuals love to say “tighten securely” – this one says “188 ± 9 Nm” and that’s what your torque wrench better read. The electrical wire code section also tells you which color wires carry what – no guessing.

Engine Overhaul: What the Manual Covers

Section 13 (Disassembly and Assembly) walks you through pulling the engine down to the block and building it back. Section 14 (Maintenance Standard) tells you the wear limits for cylinder liners, pistons, rings, crankshaft journals – everything. If you’re rebuilding a 108-2, you need those numbers. The manual doesn’t assume you know how to measure; it tells you the spec and the tool. Section 15 covers repairs like grinding the valve seat and replacing cam bushings. I’ve seen too many guys skip the pressure test on page 15-7 – don’t be that guy.

Electrical System: Why OEM Wiring Matters

The electrical section in Structure and Function (chapter 11) includes actual wiring diagrams – not redrawn approximations. It covers the alternator, starting motor, glow plugs, oil pressure switch, and relay switch. If you get a no-start condition on a 108-2, the troubleshooting chart (section 12) has 16 symptom codes. S-2 covers exactly why the engine won’t start: whether it turns or not, whether fuel is injected, whether exhaust comes out. That’s diagnostic precision you won’t find in a Chilton manual. For related electrical systems on other Komatsu models, check the Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual which shares similar wiring logic.

Why OEM Beats Aftermarket Every Time

I’ve compared this factory manual to three different aftermarket versions. The aftermarket ones left out the boost compensator adjustment procedure for the fuel injection pump. This one includes the speed control lever angle specs and the procedure for adjusting the fuel cut solenoid linkage. The safety section alone – with hoisting instructions and push-pull coupler disassembly method – keeps you from crushing your hand or dropping the engine. Aftermarket publishers don’t care about liability. Komatsu does. That’s why I trust the factory print. For wheel loader engines with similar architecture, see the Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual.

Troubleshooting That Saves Your Weekend

Section 12 has a troubleshooting matrix that covers poor starting, no start, hunting, lack of output, black smoke, blue smoke, oil contamination, overheating, abnormal noise, and excessive vibration. That’s 16 specific symptom codes. Each one lists possible causes and corrective actions. For example, S-6 (engine lacks output) tells you to check fuel injection timing, boost compensator, and turbocharger. No fluff – just a chart. If you’re working on a Manual Transmission or engine that behaves like a manual transmission in terms of load response, the same diagnostic principles apply. Another external resource on Manual Transmission basics can help if you’re new to engine-transmission interaction, but for the 108-2 itself, this manual is all you need.

For larger Komatsu power units, the Komatsu PW95R-2 Workshop Manual – 520 Pages of Factory Specs offers similar depth for a different platform.

Q: Can I use this manual for a 108-2 engine that’s been swapped into a non-Komatsu machine?

Yes. The manual covers the engine standalone. The fuel system, cooling, lubrication, and electrical diagrams don’t depend on the mounting. You’ll still need the machine-specific wiring for the chassis or transmission, but the engine side is fully covered.

Q: What torque value does the manual provide for the cylinder head?

Page 26 lists the standard tightening torque for bolts in the 24 mm class. Exact value depends on grade – the manual includes a table. You must cross-reference the bolt size and material.

Downloading this manual gives you the same paper that Komatsu technicians pull off the shelf. No digital alterations, no missing pages – just the 226-page PDF with clickable bookmarks. Access the Factory Manual and have the specs in front of you before you turn a wrench.