Komatsu GD525A-1C(S/N 60001-UP)

The Komatsu GD525A-1C (S/N 60001-up) is a mid-size, rigid-frame motor grader used for road maintenance, fine grading, and site finishing. It sits in the GD500-series lineup between the lighter GD511A-1/GD513A-1 class (built around Komatsu's smaller S6D95L engine) and the heavier GD605/GD625A-1 class (built around the 6D125 engine family). Parts-fitment records across water pumps and engine overhaul kits tie the GD525A-1 line most consistently to Komatsu's 6D105-1 / S6D105-1 turbocharged diesel family, shared with siblings like the GD505A-2/-3, GD521A-1, and GD523A-1. Standard operating weight runs roughly 12.6 to 13.5 tonnes (about 27,800 to 29,800 lb) depending on tire, ripper/scarifier, and ballast configuration, with a moldboard in the roughly 3.7 m (12 ft) class typical of this size grader. The GD525A-1C is the third running change within the GD525A-1 family: the line began at S/N 50001 with the GD525A-1 and GD525A-1A, moved to S/N 55001 for the GD525A-1B, and reached S/N 60001 for this -1C update, all built and documented under the same factory shop manual.

Across the A-1 through A-1C running changes, Komatsu kept the same core engine and drivetrain architecture while updating hydraulics, electrical routing, and detail components at each serial break rather than issuing a full redesign. That means engine, filtration, and driveline parts commonality carries well across the whole GD525A-1 family, while brackets, harnesses, and some hydraulic valve components are specific to a given serial range and need to be matched to the -1C build. In the used and parts market today, that combination is exactly why this generation still moves: a mechanically simple, non-electronic diesel with broad parts commonality across several GD500-series siblings, at a size class that covers most municipal and contractor grading work without the cost or complexity of a larger, electronically controlled grader. Buyers and parts sourcers should still confirm exact serial-range fitment before ordering, since the -1C update (S/N 60001-up) is a distinct break from the earlier -1, -1A, and -1B serial ranges.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.