Caterpillar 323D

The Caterpillar 323D is a mid-size crawler hydraulic excavator in Caterpillar's 20-24 tonne class, built from roughly 2007 through 2014 and powered by the Cat C6.4 ACERT turbocharged diesel rated at approximately 110 kW (147 hp) net flywheel power, with some dealer literature rounding this to 150 hp (112 kW). Operating weight runs roughly 23,000 to 24,000 kg (50,700 to 52,900 lb) depending on boom, stick, and track shoe width fitted. The 323D introduced the 323 size class into Caterpillar's D-series excavator lineup, slotting between the smaller 320D and larger 325D, and was offered in several undercarriage and application configurations sold under the 323D name family, including a long-undercarriage mass-excavation setup, a long-narrow undercarriage version for confined sites, and sewer/pipe-laying configurations with reduced tail swing and grease-lubricated tracks. It was followed by the 323E, which moved to the Cat C6.6 ACERT engine and Tier 4 Interim/Stage IIIB emissions controls starting around 2012, then later by the 323F and by Caterpillar's next-generation 323 platform built around the Cat C7.1 engine.

Across the changeover from 323D to 323E and beyond, the biggest shift was emissions technology and electronics: the 323D's C6.4 ACERT engine uses simpler, largely cooled-EGR-based emissions control without the diesel particulate filter and selective catalytic reduction hardware that later Tier 4 Final machines carry, which keeps the 323D mechanically simpler to own and easier to diagnose in the field. That simplicity, combined with the large number of these machines sold worldwide and strong parts commonality across the D-series family, is exactly why the 323D still holds a solid position in the used and parts market today: buyers get a proven mid-size digging machine without aftertreatment maintenance costs, and the supply of used engines, hydraulic components, and undercarriage parts remains deep. The tradeoff is that the 323D name covers several distinct undercarriage and application variants (L, LN, S, SA) that share many components but not all of them, so confirming the exact configuration from the machine's serial plate before ordering parts is essential.

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.