Description

Komatsu 108 Series 1998 Workshop Manual

If you’re tearing down a Komatsu 108 Series 1998 Workshop Manual engine, you need the factory book. Not a generic reprint. Not a PDF scraped from a forum. This is the 254-page OEM manual published by Komatsu in 1998. It’s what the dealer techs used. I’ve used it myself on a 108 Series that came in with a blown head gasket – the coolant was mixing with oil. Without the right sequence and torque on the cylinder head bolts, you’re wasting gaskets and time. This manual gives you the procedure from section 13 Disassembly and Assembly, and the maintenance standards in section 14. It’s the real thing.

254 Pages of Factory Engine Specs

At 254 pages, this manual covers the entire engine from general specifications to part repair. Section 01 gives you the engine performance curve and weight table – useful for matching replacement components. The maintenance standard section starts on page 14-1 – it lists wear limits for the cylinder liner, crankshaft journals, and valve guides. Those numbers aren’t guesses; they come from Komatsu’s engineering. I’ve seen aftermarket manuals skip the valve guide clearance spec entirely. That’s a fast track to oil consumption and a re-do.

11 Structure and Function – Engine Body and Lubrication

Section 11 breaks down the entire engine structure. You get the cylinder head, cylinder block, main revolving system, timing gear, and valve system. Each subsystem has diagrams and part callouts. The lubrication system chart shows oil flow through the pump, filter (built-in safety valve), and cooler. If you’re diagnosing low oil pressure, you need the relief valve settings – those are in the lubrication system portion. The intake and exhaust system section covers the turbocharger, after-cooler, and electronic dust indicator. That dust indicator is often overlooked; a clogged air cleaner kills turbo life.

Testing and Adjusting – Valve Clearance and Compression

Section 12 is where the diagnostic work happens. It includes adjusting valve clearance, measuring compression pressure, testing and adjusting fuel injection timing, and the procedure for the engine stop motor cable. The troubleshooting tree covers 16 symptoms from S-1 (starting poor) to S-16 (excessive vibration). For example, S-2 “Engine Does Not Start” splits into three sub-cases: engine doesn’t turn, turns but no exhaust gas, or exhaust gas comes out but no start. That kind of logic saves hours of guesswork. The testing and adjusting data at the end includes calibration numbers for the fuel system – you won’t find those in a generic manual.

Who Should Buy This Workshop Manual?

This manual is for anyone maintaining or overhauling equipment that uses the Komatsu 108 Series diesel engine – think excavators, generators, or compact loaders. DIY mechanics who have rebuilt an engine before will find the step-by-step disassembly and assembly sequences in section 13 clear and complete. Beginners should have some mechanical experience because this is a professional-level document. It assumes you know how to use a dial indicator and a torque wrench. But if you’re willing to learn, the manual gives you all the factory data you need to do the job right.

OEM Print vs Aftermarket Documentation

Aftermarket manuals often copy diagrams from earlier editions or omit critical calibration data. This is Komatsu’s own print, published in 1998 with revision marks on every page – see the list of revised pages at the front. Section 15 covers repair and replacement of parts like grinding the cylinder head mounting face, replacing valve seat inserts, and grinding the crankshaft. The pressure test procedure for the cylinder head is spelled out. Compare that to a third-party book that says “tighten to spec” without giving the spec. That’s not acceptable when you’re dealing with a 100-horsepower diesel. This manual gives you the actual numbers.

Does this manual cover the fuel injection pump?

Yes, section 11 includes fuel injection pump, nozzle, and fuel filter.

What torque values are listed for the cylinder head?

The manual provides factory torque specs in the maintenance standard and the testing and adjusting data. For cylinder head bolts, you need the tightening sequence and final torque. Section 14 lists the standard values for the cylinder head, valve clearance, and other critical fasteners. The testing and adjusting data on page 12-16-? has calibration data for the fuel system. Without these numbers, you risk warping the head or blowing a gasket. The manual includes both assembly and inspection specs.

If you need to overhaul a Komatsu 108 Series diesel engine, do not start without the factory documentation. Komatsu 108 Series 1997 Service Manual – Factory Specs for Diesel Engine Repair covers similar engines. For related equipment, see 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 refer to Manual Transmission for transmission repair and Manual Transmission for fluid specs if your application includes one. Access the Factory Manual from AutoRepairManuals.com to get the OEM data you need.