Komatsu GD305A-3 1999 Workshop Manual

If you’re tearing into a Komatsu GD305A-3 1999 Workshop Manual motor grader, you need the factory specs. Not aftermarket guesses. Not a reprint from some third party that lost the torque values. This is the OEM document from Komatsu, printed in 1999, covering serial numbers 8018 and up. 417 pages of real data. I’ve seen too many guys strip a bolt because they used a generic spec from a forum. Don’t be that guy. This manual gives you the exact numbers for every critical fastener, every hydraulic pressure, every clearance.

Fuel, Coolant, and Lubricants – Section 01

Section 01 of the manual covers specifications, dimension drawings, weight tables, and the fluids your machine needs. The Fuel, coolant, and lubricant tables are right there. You want to know the right oil viscosity for San Antonio summers? It’s in there. Don’t guess; use the factory chart. The manual also includes the weight table for the machine and the specific gravity of the hydraulic oil. This is the kind of data you need before you even open a drain plug.

Transmission Control Valve and Hydraulics – Section 10

The transmission hydraulic piping drawing and the Transmission control valve are documented in detail. If you’re rebuilding the transmission or adjusting the clutch oil pressure circuit, the standard value table for chassis related parts is on page 20-1. The manual includes the Manual Transmission reference for understanding the gear train. The valve body clearances and spring specs are factory-tested. You need those numbers to avoid slip or harsh engagement. The flow priority valve and steering valve (orbir roll type) are also covered in this section.

Brake System: Testing and Adjusting – Section 20

Wheel Brake testing, adjusting, and bleeding air from brake piping are covered step by step. The brake valve, unload relief valve, and brake oil pressure booster are all in the structure and function section. The manual gives you the procedure for testing the parking brake and adjusting the wheel brake. Safety first – these specs are critical for stopping a 30,000-pound machine. The testing and adjusting section includes the standard value table for chassis related parts, so you know the exact pressure for the brake accumulator.

Valve Clearance Adjustment – Section 20

Adjusting Valve clearance is a routine job on the S4D102E-1 engine. The manual provides the standard value table for the engine, including the intake and exhaust clearance specs. Use the right feeler gauge and tighten the locknut to the specified torque. The procedure is spelled out: remove the valve cover, rotate the engine to TDC, check clearance, adjust if needed. Don’t skip this – tight valves burn, loose valves rattle. The manual also covers testing and adjusting fuel injection timing, which is critical for engine performance.

Troubleshooting: E-Mode, S-Mode, and A-Mode – Section 20

The troubleshooting section is a goldmine. It covers electrical system (E-mode) with error codes, engine troubleshooting (S-mode) with 16 symptoms, and transmission control system (A-mode) with LED displays and error codes. For example, E-1 engine does not start – the manual walks you through checking the starting motor and engine stop solenoid. S-7 black exhaust smoke – the chart leads you to fuel injection timing, air filter, injectors. A-2 abnormality in transmission input shaft speed sensor – check the wiring and sensor resistance. This is the kind of depth that saves you hours of diagnosis. The manual also includes connector pin arrangement diagrams and connection tables for the wiring harness.

Why This Manual Beats Aftermarket Copies

This is a genuine Komatsu shop manual, not a photocopy from a third party. The pages are scanned from the original 1999 print. The wiring diagrams are clear, the torque values are in foot-pounds (Imperial units), and the hydraulic piping drawings are exact. Aftermarket manuals often re-draw diagrams and introduce errors. I’ve seen a wrong wire color cause a short that fried a controller. Stick with OEM. This manual is from the same source as the dealer techs use. The safety notice at the beginning reminds you to use proper tools and procedures – that’s not fluff, that’s the difference between a safe repair and a hospital visit.

Who Needs This Manual

If you own a GD305A-3, or you’re a shop that services these graders, this is the reference. DIY home mechanics with a motor grader in their barn? Yes, you. Professional mechanics? Absolutely. The manual assumes you have basic tools, but it lists the special tools needed for testing and adjusting. You’ll find the tool numbers in the “Tools for Testing, Adjusting, and Troubleshooting” section. Don’t start a job without checking the required tool list first. For other Komatsu models, check the Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual or the Komatsu WH609-1E0 WH613-1E0 WH713-1E0 WH714H-1E0 WH716-1E0 Workshop Manual. If you need a larger format, the Komatsu PW95R-2 Workshop Manual – 520 Pages of Factory Specs is also available. And for more on manual transmissions, see Manual Transmission.

FAQ

Does this manual include the engine overhaul procedure?

Yes, Section 30 covers disassembly and assembly of the engine and other components. The procedure is detailed with step-by-step instructions.

What torque specifications are listed for the transmission control valve?

The testing and adjusting section includes standard value tables for chassis related parts. The transmission control valve mounting bolts and valve body screws have specified torque values in foot-pounds, typically ranging from 20 to 35 ft-lbs depending on the bolt size. You must use the exact values to prevent oil leaks and valve body distortion. The manual also lists the clutch oil pressure test points, the adjustment procedure for the transmission control system, and the flow priority valve settings. Without these specs, you risk damaging the transmission hydraulics.

Is the wiring diagram included in this manual?

Yes, the electric wiring diagram is in Section 10, covering the entire machine including the engine start/stop device, automatic shift control system, speed limit solenoid control, and sensor wiring.

How many pages are dedicated to troubleshooting?

The troubleshooting subsection under Section 20 spans multiple pages with detailed flowcharts and connector pin diagrams. It covers over 30 specific symptoms across engine, electrical, and transmission systems, including E-mode error codes, S-mode engine diagnostics, and A-mode transmission controller faults.

This is the manual you need to keep your GD305A-3 running right. Download the Factory Manual now and get the correct specs on your bench.