Komatsu D600 C, D600 D, 600 C, L600 D 1983 Service Manual

Description

If you are working on a Komatsu D600 C, D600 D, 600 C, or L600 D loader and you don’t have the factory hydraulic manual, you are rolling dice with a $10,000 pump. I have seen guys guess at relief valve settings and spray oil everywhere. This 1983 Service Manual from Komatsu is the only document I trust for these machines. It’s 114 pages of Group 2200 – hydraulic system – no aftermarket fluff. You get OEM torque specs, pressure test points, and the kind of step-by-step removal procedures that keep you from snapping a bolt inside a casting. The manual even includes safety precautions that remind you about jack stands and pressurized lines. If you skip those, you might not be around to finish the job.

Hydraulic Circuit Diagrams – Which Page for Which Model

Mixing up diagrams will cost you time. The manual gives separate hydraulic circuit layouts for each variant: 600 C on page 18, D600 C on page 20, D600 D on page 24, and L600 D on page 26. Later L600 D machines get a dual-pressure circuit on page 28 and an automatic return-to-dig electrical diagram on page 28 as well. If you don’t check the model and serial number range, you’ll be chasing the wrong lines.

3-Spool Control Valve: Disassembly Sequence

Removing and replacing the control valve is covered on pages 73–79. These pages walk you through labeling hoses, pulling the spools, and inspecting the valve body for scoring. The manual also details the shift control linkage disassembly on pages 81–86 – a job that will make you curse if you don’t have the right alignment marks. Pay attention to the valve components section starting page 36; it explains the pilot-operated sections and the shock valve on page 44. I have rebuilt three of these valves, and the factory book saved me from mixing up shims.

Pressure Relief Valve: Torque and Test Procedure

The pilot-operated pressure relief valve components are shown on page 40. For removal and replacement, the manual uses pages 67–69; disassembly and reassembly for most models runs pages 70–72. The pressure test instructions for all models except later L600 D are on page 58. You need a gauge that reads to about 3,000 psi (no metric conversion here – use imperial). Page 57 covers the L600 D from serial number 3317 20 114 with a different test manifold. That page also gives the test procedure for the check valves on page 61. Do not skip the check valve test; a stuck check valve will fake you into thinking the pump is bad.

Fault Diagnosis Tables – Don’t Skip These

Three separate diagnosis tables sit on pages 50–55. One covers 600 C and L600 D (page 50), another covers D600 C and D600 D (page 53), and the third covers hydraulic pump and relief valve on all models (page 55). If your machine won’t lift or has erratic steering, the table gives you a path: possible causes, what to check, and the correct torque for the relief valve locknut. I have seen beginners waste half a day because they didn’t use page 55 to verify pump pressure first.

Safety Precautions – The Manual Gets It Right

The preface (page 3) lays out rules that keep you alive: never crack a hydraulic line under pressure, never start the engine from beside the machine, and always block the axles before crawling underneath. This isn’t generic boilerplate – it’s specific to these loaders. If you are a home garage mechanic, read that page twice. The manual also warns about using rated hoists and slings when removing cylinders – pages 63–66 for hydraulic pump removal, pages 87–91 for lift cylinders on D600 C/D. A 50-lb pump hurts your back and your wallet if it falls.

What About Parts and Specifications?

Every component chapter lists exploded views with part numbers. For instance, the bucket cylinder components for 600 C up to serial number 310 06 098 live on page 102; lift cylinder components for L600 D on page 105. The oil cooler bypass valve components are on page 47. You will also find the shift control linkage details on page 48. If you need the dual-pressure relief valve components, go to page 43. The book gives you the bare minimum cell counts – no padding.

For related equipment, see Demag Komatsu H 285 S Service Manual – 544 Pages of Factory Specs if your shop handles larger machines. For the wheel loader line, Komatsu WA430-6 Service Manual – 306-Page OEM Shop Manual and Komatsu WA470 2000 Service Manual – Factory Specs for Wheel Loaders cover later models. If you need a refresher on basic transmission theory, Manual Transmission on Wikipedia explains gear ratios. For overall manual transmission repair, Manual Transmission provides additional background.

Do not guess on hydraulic pressures. This 1983 Service Manual is the real deal – original OEM print, not a copy. Access the Factory Manual now and put it on your tablet or print the pages you need. Your hydraulic system will thank you.