Komatsu WA120-1(S/N 10001-UP)

The Komatsu WA120-1 (S/N 10001-UP) is a compact, four-wheel-drive articulated wheel loader built roughly from 1987 into the early-to-mid 1990s. It runs a Komatsu 6D95L-1Z, a naturally aspirated in-line six-cylinder diesel rated at approximately 52-59 kW (70-80 hp), fed by a fully mechanical jerk-type injection pump with no electronic engine management, so operator warnings come from a monitor panel of individual pilot lamps (oil pressure, charge, coolant temperature, air cleaner restriction, torque converter oil temperature) and a buzzer, not digital fault codes. Operating weight runs around 8,000 kg (about 17,600 lb), and the factory general-purpose bucket falls in the roughly 1.1-1.4 m3 (1.4-1.8 yd3) range depending on the bucket fitted, with rock/heavy-duty and light-material buckets plus pin-on forks also offered. Komatsu built this generation with either an open ROPS canopy or an enclosed ROPS cab. This S/N 10001-UP range covers the standard-chassis WA120-1; the longer-chassis WA120-1LC ran on its own A20001-UP serial series with a different engine and is a separate machine, not a configuration option within this range.

No confirmed direct predecessor to the WA120-1 badge is documented; the S/N 10001-UP range appears to be Komatsu's first WA120-nameplated small loader generation, using a plain numeric serial that predates Komatsu's later letter-prefix PIN system. Komatsu carried the WA120 name forward with the WA120-3, a later generation built under its own 50001-UP and 53001-UP serial blocks with an updated engine and, on emission-spec variants, different tuning - a distinct generation, not a running change within this serial range, so parts and specs should not be assumed interchangeable. In the used and parts market, this early WA120-1 generation holds up as a simple, all-mechanical small loader: no control modules, sensors, or electronic injection to fail, a 6D95L engine family shared with other Komatsu machines of the same era for easier parts sourcing, and a size class that still suits yard, site, and light municipal loading work. Buyers value it as a machine they can service and rebuild without a scan tool, though factory literature and dealer parts support for this specific 1987-era serial range run thinner than for the newer WA120-3.

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.