Description

Komatsu GD500R-2, GD505R-2, GD505A-2 1989 Workshop Manual

I have been turning wrenches for 28 years. When I see an aftermarket manual, I usually throw it in the trash. This 1989 Komatsu factory manual for the Komatsu GD500R-2, GD505R-2, GD505A-2 1989 Workshop Manual is the real deal. 849 pages of what the engineers wrote, not some third-party guess. You need correct engine specs for the GD500R-2? It is in section 10. You need to understand the hydroshift transmission on the GD505R-2? Section 22 has the testing and adjusting procedures. This is not a reprint of a copy; this is the original OEM print from Komatsu, printed in Japan in March 1989.

Engine Overhaul: Cylinder Head Torque and Assembly

Section 13 of this manual covers disassembly and assembly of the engine, including the cylinder head. The procedure for mounting the cylinder head lists every bolt torque sequence. No guessing. You also get the process for the fuel injection pump, nozzle holder, turbocharger, and damper. The manual tells you the tools required for testing and adjusting in Section 12—cranking method, intake and exhaust system checks, fuel system pressures. If you are pulling the engine out of a GD505A-2, the mounting instructions are there.

Does This Manual Cover the Hydroshift Transmission?

Yes. The GD505R-2 and GD505A-2 use a hydroshift transmission. Section 21 gives the structure and function, including the control valve, hydraulic control piping, and lubrication system. Section 22 has the testing and adjusting procedures. It includes a troubleshooting table with specific symptoms: excessive shock when shifting, time lag, machine fails to start. Each symptom has a step-by-step diagnostic path. You also get the inching pedal stroke and operating force specs. For the GD500R-2, the manual covers the main clutch and inertia brake. All adjustment specs are factory validated.

3 Sections That Save You From Guesswork

Section 12 – Testing and Adjusting for the engine. It lists standard values for compression, fuel injection timing, cooling system pressures. Section 22 – Power train testing with diagnosis tool table and troubleshooting for main clutch and transmission. Section 62 – Hydraulic system testing and adjusting. Each section gives the required tools and the exact measurements to verify. No vague “tighten until snug” garbage. It tells you the tool part numbers and the tolerances.

Get the Right Fuel Injection Pump Procedure

Section 13 details the dismounting and mounting of the fuel injection pump. The manual shows the sequence for removing the pump without damaging the drive gear. It also covers the nozzle holder and turbocharger. Aftermarket manuals often skip the orientation marks for the injection timing. This manual shows you where the marks are and how to set static timing. If you are working on a GD505R-2, you need that precision. The water pump and oil cooler disassembly are also in this section.

Power Train Diagnostics: Testing and Adjusting

Section 22 is where you live when the grader acts up. It starts with a diagnosis tool table—what gauges and adapters you need. Then it goes through six specific problems for the GD505-2 models: main clutch slip, gear slip out, excessive shock, time lag, machine fails to start, machine travels slowly. Each problem has a numbered checklist. For the GD500R-2, it covers the main clutch and transmission control lever stroke. The manual includes cross-references to the structure section so you can see the internal parts while you diagnose.

Source Authenticity: Aftermarket Manuals vs. Factory OEM

I have seen aftermarket manuals that list the wrong oil capacity for a transmission—ruining a rebuild in under 50 hours. This manual was printed by Komatsu. The torque values come from their engineering department. The wiring diagrams in Section 91 Electrical are exact. If you are a DIY mechanic or a shop owner, the difference between a repair that holds up and one that fails is having the original factory data. This is the same manual the dealer techs used. No third-party editing, no missing pages.

For other Komatsu equipment, check out the Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual for wheel loaders, or the Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual for excavators. If you need a smaller grader manual, see the Komatsu PW95R-2 Workshop Manual – 520 Pages of Factory Specs. For background on how a manual transmission works, refer to Manual Transmission on Wikipedia. The hydroshift in the GD505-2 is a type of Manual Transmission with hydraulic assist—knowing that helps when you are diagnosing shift issues.

What does this manual cover?

GD500R-2, GD505R-2, and GD505A-2 motor graders from 1989.

Why buy an original manual instead of a third-party reprint?

Third-party reprints often copy from copies, losing clarity and sometimes altering specs. This manual is a direct scan of the original Komatsu publication. The torque values, clearances, and electrical diagrams are exactly what the factory used. I have seen aftermarket manuals list the wrong oil capacity for a transmission, causing failures. With this 849-page OEM manual, you get the genuine procedures for engine disassembly, hydroshift transmission troubleshooting, and brake system adjustments. Safety warnings are intact. The difference between a repair that lasts and one that comes apart on the job site is having the correct data. This manual gives you that data.

If you are working on one of these graders, do not rely on a generic guide. Click the button to access the factory manual.