Caterpillar C27

The Caterpillar C27 is a 27.0 L (1,649 in³), V12, four-stroke diesel engine sold as a bare power unit for standby and prime generator sets, industrial and land-mechanical duty such as pumps and well-service equipment, and marine propulsion or auxiliary power. Bore and stroke run about 137 mm x 152 mm (5.4 in x 6.0 in) with a compression ratio near 16.1:1 (a minority of spec sheets list 16.5:1), twin turbochargers, and Caterpillar's ADEM electronic control paired with mechanically actuated unit injectors (MEUI). As a generator set it runs at 1800 rpm for 60 Hz output, packaged in standby ratings from roughly 750 to 800 ekW (1,006-1,073 hp) and prime ratings from roughly 680 to 725 ekW (912-972 hp); industrial and marine versions of the same platform are rated up to about 858 bkW (1,150 hp) depending on duty cycle and emissions tier. Bare engine dry weight is about 3,004 kg (6,625 lb); packaged genset weight runs considerably higher and varies with enclosure, radiator, and fuel-tank options. The C27 entered production around 2000 as the electronically governed successor to the mechanical 3412/3412C/3412E on the same 27-liter V12 block, and it remains in Caterpillar's current lineup for generator sets, well-service engines, and industrial power, sitting one step below the larger 32.1 L C32 in the modern mid-range family.

Across its run the core 27 L block and V12 architecture have stayed the same, but emissions control has moved through several stages: early standby and industrial units met Tier 2-equivalent stationary standards, mid-run land-mechanical and mobile generator versions added Tier 4 Interim control, and current well-service and industrial C27 ACERT engines are certified to Tier 4 Final. Electronic governance advanced through ADEM generations while the twin-turbo MEUI fuel system carried through largely unchanged. Because the C27 shares its block, bore, and stroke with the long-running 3412 family, cylinder components, turbochargers, and unit injectors interchange broadly across generations, which supports a healthy rebuild and parts market. Retired standby plants, decommissioned well-service pump packages, and marine repowers keep a steady supply of used C27 engines and generator sets in circulation, making it one of the more serviceable large-bore Cat diesels on the used-equipment market today.

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.