Description

Komatsu D155A-2 2002 Workshop Manual

I’ve been wrenching on heavy equipment for 28 years. You start seeing patterns. One of them is that a guy who tries to set valve clearance on a D155A-2 engine without the factory numbers is asking for a burned valve. This 2002 Komatsu D155A-2 Workshop Manual is the real thing – 462 pages of the documentation Komatsu shipped to dealer techs. No reprints. No aftermarket condensation. Just the spec sheets, circuit diagrams, and torque tables you need to keep that SA6D140-2 engine and powershift transmission running.

Engine and Fuel System: Section 01 General Specs

Section 01 starts with the SPECIFICATION DRAWING and a SPECIFICATIONS table that lists the weight and dimensions. The TABLE OF FUEL,COOLANT AND LUBRICANTS is right there – don’t guess on oil grade for the torque converter. You’ll find the exact capacities and fluid types. Fuel system specs are included for injection timing adjustments later in the manual. Having this page open saves you a trip to the parts counter for the wrong filter.

Transmission and Power Train: Section 10 Structure and Function

Section 10 is dense – 90+ pages covering everything from the TORQUE CONVERTER to the TRANSMISSION CONTROL VALVE and the STEERING BRAKE system. The POWER TRAIN HYDRAULIC CIRCUIT DIAGRAM shows the flow paths for clutch engagement. The TRANSMISSION section details the planetary gearsets and the lubrication relief valve. If you are working on the bevel gear shaft or final drive, the cross-section drawings are there. A third-party manual will skip the spring-assist brake system details – this one doesn’t.

Testing and Adjusting: Valve Clearance and Torque Specs

Section 20 is where you live during a rebuild. It starts with STANDARD VALUE TABLE FOR FUNCTIONS RELEVANT TO THE ENGINE – including intake manifold pressure (boost), exhaust temperature, and compression pressure. The ADJUSTING THE VALVE CLEARANCE procedure gives you the cold lash settings. Need to measure the engine oil pressure? It tells you which port and what gauge size. The INSPECTING AND ADJUSTING THE FUEL INJECTION TIMING procedure is written step-by-step. Torque values for the injection pump and cylinder head are in the maintenance standard section – not buried in a footnote.

Troubleshooting: E-Mode and H-Mode Diagnostics

Troubleshooting is split into electrical (E-mode) and hydraulic/mechanical (H-mode). E-mode covers the engine not starting (E-1), lamps not turning on, pre-heating failure, and the pin puller system. Each fault has a flow diagram and connector pin number table. H-mode covers torque converter oil temperature too high (H-1), machine won’t travel (H-2), weak tracking force, and steering clutch slip (H-9). The CONNECTION TABLE FOR CONNECTOR PIN NUMBERS lets you trace a short without a meter up your sleeve. Page references are given for each circuit diagram.

Why Factory OEM Documentation Beats Aftermarket

Third-party manuals skip the revision marks. This one has a LIST OF REVISED PAGES with clear marks for added, replaced, or deleted pages. That’s how you know if a torque spec has been updated. Komatsu’s own shop manual includes bulletins about attachments and optional equipment that aren’t available in your area – they tell you up front. The engine section references the separate SA6D140-2 engine manual because they expect you to have the full set. If you are relying on a scanned copy that someone condensed, you are taking a risk on the transmission control valve calibration. Don’t.

Does this manual cover the SA6D140-2 engine?

Yes. Section 20 has all engine function standards. The engine itself is detailed in a separate 6D140-2 Series Engine Shop Manual, but this manual gives you the mounting and integration specs.

Are the wiring diagrams complete?

Section 10 includes the ACTUAL ELECTRIC WIRING DIAGRAM and the MONITOR SYSTEM with sensor locations. The E-mode troubleshooting guides reference specific connector pin numbers and include flow diagrams for the head lamps, pre-heating, and pin puller solenoid valve. Page numbers are printed right on the diagrams – no scanning to find the right sheet.

What torque conversions are needed for metric fasteners?

None. All torque values in the manual are printed in the factory units – use a torque wrench calibrated to the spec for your fastener size. The MAINTENANCE STANDARD section lists fastener torque for each joint.

Can I use this manual for a D155A-1?

This manual is specifically for D155A-2 serial number 57001 and up. The power train and engine control system differ from earlier models. Stick to the correct model to avoid mismatched clutch pressures and valve clearance specs.

If you are going to tear into a D155A-2 transmission or adjust the valve lash, you need the factory data. Access the Factory Manual from AutoRepairManuals and keep it on your tablet next to the machine. It’s cheaper than one mistake on the torque converter.

Related manuals you may need: Komatsu D155A-2 2002 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. For background on planetary gearset operation, see Manual Transmission and Manual Transmission.