Caterpillar CAT C12 Engine for Sale | OEM Used 12L Inline-6 Turbocharged Diesel for Class 8 Trucks, Marine, Industrial
$12,000.00
At a Glance
- Condition: OEM used, top-end inspected and ECM-documented before shipping
- Availability: In stock, pre-ACERT and ACERT (2004-2007) variants available
- Shipping: Free shipping to all 50 states via crated freight, 7 to 14 business days
- Variant confirmed (pre-ACERT vs ACERT)
- ECM serial number documented for Cat Connect compatibility
- Top-end inspection (heads, EUI injectors, rocker arms)
- Turbocharger and aftercooler inspected for wear
- Donor application documented (Class 8 truck, construction, marine, military, etc.)
- 100% inspection before every order ships
- Backed by a 15 day replacement warranty against internal defects
Description
About the Caterpillar CAT C12 Engine
Looking for a powerful and reliable diesel engine? The CAT C12 engine for sale stands out as an ideal choice. Known for its versatility and robust performance, the CAT C12 is a favorite among heavy-duty truck drivers, marine propulsion operators, construction equipment fleets, military operators, fire service departments, and industrial power generation applications.
The C12 Family Position
The Caterpillar C12 sat in the middle of Caterpillar heavy-duty diesel lineup during its 1999-2007 production years:
- C9 (9 liters), smaller heavy-duty applications
- C12 (12 liters), THIS LISTING, mid-range heavy-duty applications
- C13 (13 liters, ACERT), successor to the C12 in the on-highway truck market starting 2007
- C15 (15 liters, our vaz85 listing), Class 8 line-haul applications, the legendary 6NZ pre-ACERT and MXS / SDP / 6TZ ACERT variants
The C12 was uniquely positioned as Caterpillar most versatile mid-range diesel, finding homes in applications where the C9 was too small and the C15 was too large or too heavy. This versatility is why you see the C12 in everything from over-the-road trucks to MRAP military vehicles to luxury yachts.
Features of the CAT C12 Engine for Sale
- High Horsepower: Up to 490 bhp, providing substantial power for various applications
- Peak Torque: Rated at 1,650 ft-lb at 1,200 rpm, ensuring excellent low-end pulling power for hauling, mobile crane operation, and heavy construction equipment use
- Emission Compliance: Meets IMO II emission standards, making it suitable for marine and industrial applications
- Advanced Fuel System: EUI (Electronic Unit Injection) provides precise fuel delivery for efficient consumption and reduced emissions
- Durable Build: Engineered for long-lasting performance with an average life expectancy of 850,000 to 1,000,000 miles before inframe rebuild
- Versatile Applications: Suitable for Class 8 trucks, motor coaches, construction equipment, military vehicles, fire trucks, marine propulsion, and industrial power generation
- Cooling Systems: Combined air and liquid-cooled configuration to maintain optimal operating temperatures across diverse duty cycles
- ACERT Technology (2004-2007 variants): Advanced Combustion Emission Reduction Technologies, Caterpillar solution for meeting tightened EPA emissions standards while maintaining power output
C12 Engine Fits These Applications
The Caterpillar C12 was deployed across an extraordinary range of platforms. This diversity is one of the key reasons the C12 is sought after as a replacement, repower, and refurbishment engine:
Marine Applications
| Vehicle | Compatibility |
|---|---|
| Commercial Vessels | Tugboats including Damen Stan Tug 1606, fishing boats including the North River 38′ Bristol Bay Gillnetter |
| Pleasure Craft | Yachts including Sunseeker Manhattan 55, recreational boats including Viking 55 Convertible |
Industrial Applications
| Vehicle | Compatibility |
|---|---|
| Power Generation | Caterpillar C12 Generator Set (Model: C12-50HZ) for prime and standby power |
| Pumps and Compressors | Gardner Denver well-service pumps, Sullair 185 Series air compressors |
Construction Equipment
| Detail | Description |
|---|---|
| Excavators | Caterpillar 330C L, Caterpillar 345B |
| Wheel Loaders | Caterpillar 966G, Caterpillar 972G |
Agricultural Machinery
| Detail | Description |
|---|---|
| Tractors | Challenger MT965C |
| Harvesters | Claas Lexion 770 |
Trucking and Transportation
| Detail | Description |
|---|---|
| Heavy Trucks | Freightliner Columbia, Kenworth T800, Peterbilt models |
| Buses | Van Hool C2045 motor coach |
Military and Defense
| Detail | Description |
|---|---|
| Military Vehicles | BAE Systems RG33 Armored Personnel Carrier, Navistar MaxxPro MRAP (Mine Resistant Ambush Protected vehicle) |
Emergency and Specialty Vehicles
| Vehicle | Compatibility |
|---|---|
| Fire Trucks | Pierce Arrow XT, E-ONE Cyclone II |
| Specialty Vehicles | Manitowoc 999 Mobile Crane, Oshkosh M1070 HET (Heavy Equipment Transporter) |
Performance and Durability
One of the most appealing aspects of a CAT C12 engine for sale is its impressive life expectancy. Typically, these engines are good for about 850,000 to 1,000,000 miles before requiring an inframe rebuild. This exceptional longevity is why the CAT C12 continues to be a popular choice among heavy-duty engine users across trucking, marine, construction, military, and industrial sectors.
Certifications and Compliance
Each CAT C12 engine for sale meets stringent emission standards, specifically IMO II. This certification ensures that the engine you purchase is environmentally compliant and meets industry regulations for marine, on-highway, and industrial applications.
Additional Features
- ACERT Technology: The 2004-2007 production C12 variants come equipped with ACERT (Advanced Combustion Emission Reduction Technologies), enhancing fuel efficiency and reducing emissions through optimized combustion timing and Variable Valve Actuation (VVA)
- EUI Fuel Injection: Electronic Unit Injectors deliver precise fuel control with each injector independently managed by the engine ECM
- Robust Construction: Cast iron block, forged steel crankshaft, and heavy-duty bearings designed for the demanding duty cycles of Class 8 trucking, military operation, and industrial 24/7 service
The CAT C12 engine for sale is a powerful, reliable, and versatile option for those needing a robust diesel engine. Whether for heavy-duty trucks, marine propulsion systems, construction equipment, military vehicles, fire trucks, or industrial power generation, this engine meets various demanding requirements and promises longevity and excellent performance. Find the Cat C12 Engine for sale at Part Nests, at the best price.
Signs You Need a Replacement C12
- Loss of compression on one or more cylinders
- EUI injector failure (rough running, fault codes, smoke)
- Turbocharger failure (boost drop, blue oil smoke, whistle / surge sounds)
- Cylinder head crack (coolant in oil, white smoke, overheating)
- Connecting rod or main bearing knock under load
- ACERT-specific: VVA solenoid wear, EGR-related concerns on later variants
- Donor truck / equipment / vessel has been totaled or decommissioned
- High-mileage repower of an aging Class 8 truck, fire truck, motor coach, or marine vessel
- Construction equipment overhaul (CAT 330C, 345B, 966G, 972G)
Common C12 Maintenance Considerations
- Oil and filter changes: Every 25,000 to 50,000 miles for trucks, every 250 to 500 hours for industrial / marine / construction applications
- Fuel filters: Critical for EUI injector longevity, change at every oil interval or sooner in dusty / contaminated fuel environments
- Cooling system: Service every 2 to 3 years (or per Cat operating manual), with attention to aftercooler condition due to combined air / liquid cooling architecture
- EUI injector service: Have injectors flow-tested at major service intervals, replace as needed
- Turbocharger inspection: Check shaft play and exhaust housing condition periodically
What Ships and What Does Not
| Item | Details |
|---|---|
| INCLUDED | Long block: cast iron block, forged crankshaft, connecting rods, pistons, camshaft, cylinder heads, valve train, EUI injectors (typical), turbocharger (typical), aftercooler (typical from donor), oil pan, valve covers. |
| NOT INCLUDED | ECM (sold separately, application-specific to truck / equipment chassis and ECM serial number requirements), wiring harness, intake manifold (typical), exhaust manifold (typical), starter, alternator, A/C compressor, water pump, thermostat, oil cooler, transmission, motor mounts. |
| Fluids | Drained before shipping. Refill with Cat-approved engine oil meeting ECF-3 spec or higher (15W-40 mineral or synthetic per Cat operating manual). |
| Provenance Note | Donor application disclosed where available (Class 8 truck, fire truck, construction equipment, military vehicle, marine vessel, industrial). ECM serial number documented for buyer’s Cat ET / Cat Connect compatibility verification. |
| Core Note | No core charge. You are not required to return your old engine. |
Vehicle Compatibility
The Caterpillar C12 was used across an extraordinarily diverse range of applications:
| Vehicle | Compatibility |
|---|---|
| Class 8 Heavy-Duty Trucks | Freightliner Columbia, Kenworth T800, Peterbilt models |
| Motor Coach Buses | Van Hool C2045 |
| Construction Equipment | Caterpillar 330C L excavator, Caterpillar 345B excavator, Caterpillar 966G wheel loader, Caterpillar 972G wheel loader |
| Agricultural Equipment | Challenger MT965C tractor, Claas Lexion 770 harvester |
| Military Vehicles | BAE Systems RG33 APC, Navistar MaxxPro MRAP |
| Fire Trucks | Pierce Arrow XT, E-ONE Cyclone II |
| Specialty Vehicles | Manitowoc 999 mobile crane, Oshkosh M1070 HET |
| Marine Propulsion | Tugboats (Damen Stan Tug 1606), fishing boats (North River 38′ Bristol Bay Gillnetter), yachts (Sunseeker Manhattan 55, Viking 55 Convertible) |
| Industrial / Power Generation | Caterpillar C12-50HZ generator set, Gardner Denver well-service pumps, Sullair 185 Series air compressors |
Variants exist with different ECM calibrations for on-highway truck, vocational, marine, industrial, and military service. Tell us your application and we will match the appropriate C12.
Inspection Workflow
Every used Caterpillar C12 we ship goes through this process:
- Variant confirmed (pre-ACERT vs ACERT)
- ECM serial number documented for Cat Connect / Cat ET compatibility
- Cylinder head visual inspection for cracks
- Top-end inspection (heads, EUI injectors, rocker arms)
- EUI injector operation tested where possible
- Turbocharger inspected for shaft play and bearing wear
- Aftercooler condition inspected
- Donor application photographed and documented (Class 8 truck, fire truck, construction, etc.)
- Approximate hours / mileage documented when verifiable from donor
Why Buy From Part Nests
- Variant authenticated (pre-ACERT vs ACERT) for ECM compatibility
- ECM serial number documented for Cat ET / Cat Connect verification
- Top-end inspection (heads, EUI injectors, rocker arms)
- EUI injector operation tested where possible
- Turbocharger and aftercooler inspected
- Donor application traced across the C12 diverse deployment platforms
- Crated freight delivery to all 50 states for vintage / Class 8 / industrial engines
- 15 day replacement warranty on internal defects
- Cat-experienced support team on the phone with knowledge of pre-ACERT vs ACERT differences and the C12 diverse applications
- Call (240) 306-7051 to confirm variant (pre-ACERT vs ACERT), ECM serial number for Cat Connect, donor application (truck, fire truck, military, construction, marine, industrial, agricultural), and Cat family lineage questions (C9, C12 per this listing, C13 successor, C15 per vaz85 listing) before ordering
15 Day Replacement Warranty
Every used Caterpillar C12 engine purchased through Part Nests carries a 15 day replacement warranty starting on the delivery date.
What Is Covered
- Internal defects already present when the engine arrives
- Compression failures on any of the 6 cylinders beyond what was disclosed
- Cylinder head crack failures within 15 days from installation (where head was documented as crack-free at shipping)
- EUI injector failures within 15 days from installation (where injector operation was documented at shipping)
- Turbocharger failures within 15 days from installation (where turbo was documented as functional at shipping)
- VVA solenoid failures within 15 days from installation on ACERT variants
- Connecting rod, lifter, or bearing failures within 15 days from installation
- Incorrect variant shipped (pre-ACERT vs ACERT) due to an error on our end
What Is Not Covered
- Damage caused during installation
- Damage from running with contaminated fuel (water, dirt, particulates)
- Damage from extended oil change intervals or incorrect oil viscosity (Cat-approved ECF-3 or higher 15W-40 required)
- Damage from operating with incorrect coolant or neglected cooling system
- Damage from aggressive aftermarket tuning beyond Cat-approved fuel maps
- EGR-related failures on ACERT variants if the EGR cooler has been deleted or modified
- External components (ECM if separately documented, turbocharger if separately documented, harness, intake manifold, exhaust manifold, starter, alternator, A/C, water pump, oil cooler) unless itemized
- Labor expenses of any kind
To start a warranty claim, reach us within 15 days of delivery at (855) 634-4447.
- Variant Confirmed: Pre-ACERT or ACERT (2004-2007) documented for ECM matching
- ECM Serial Number Documented: Cat Connect / Cat ET compatibility verifiable
- Top-End Inspection: Heads, EUI injector cups, rocker arms assessed
- Turbocharger Inspected: Shaft play and bearing wear evaluated
- Cat Family Position Preserved: Mid-range between C9 and C15 (vaz85 listing)
- 15 Day Replacement Cover: Internal defects protected from delivery onward
Additional information
| aspiration | Turbocharged and aftercooled |
|---|---|
| block-material | Cast iron |
| bore-x-stroke | 5.12 in x 6.18 in |
| configuration | 6-cylinder Inline |
| coolant-capacity | 2.7 gallons |
| cooling-system | Air and liquid-cooled |
| fuel-system | Electronic Unit Injection (EUI) |
Two generations distinguished by emissions controls. The pre-ACERT C12 (1999-2003) was produced before EPA 2004 emissions standards required EGR and VVA. The ACERT C12 (2004-2007) added Caterpillar's ACERT (Advanced Combustion Emission Reduction Technologies) which includes Variable Valve Actuation (VVA), Exhaust Gas Recirculation (EGR), and refined combustion timing to meet EPA 2004-2007 emissions while maintaining power output. ACERT variants are more emissions-compliant but more complex to service. The ECM and parameter files differ between the two generations. We confirm variant before shipping for ECM matching.
Mid-range Cat diesel, between the C9 (9L) and the C15 (15L, our vaz85 listing). The full family during the 1999-2007 era: C9 (9 liters, smaller heavy-duty applications), C12 (12 liters, this listing, mid-range), C13 (13 liters ACERT, the C12 successor in the on-highway truck market starting 2007), and C15 (15 liters, the legendary Class 8 line-haul engine with pre-ACERT 6NZ and ACERT MXS / SDP / 6TZ variants per our vaz85 listing). The C12 is uniquely positioned as Caterpillar's most versatile mid-range diesel, finding homes everywhere from over-the-road trucks to MRAP military vehicles to luxury yachts. The C13 ACERT became the C12 effective successor in the on-highway truck market starting 2007.
Electronic Unit Injectors. EUI is Caterpillar's electronic fuel injection system for the C12 (and earlier engines). Each cylinder has its own EUI unit injector mounted directly in the cylinder head. The injectors are camshaft-actuated mechanically but electronically controlled by the engine ECM, which manages injection timing, duration, and pilot injection events for emissions and power optimization. EUI is different from HEUI (used on the Cat 3406E and Ford 7.3 Powerstroke per our vaz118 listing), which uses high-pressure engine oil to actuate the injectors. EUI is also different from MEUI used on the C15 (our vaz85 listing). EUI injectors should be flow-tested at major service intervals and replaced as needed.
Extraordinarily diverse, one of the C12's defining characteristics. Class 8 trucks: Freightliner Columbia, Kenworth T800, Peterbilt models. Motor coaches: Van Hool C2045. Construction equipment: CAT 330C L excavator, CAT 345B excavator, CAT 966G wheel loader, CAT 972G wheel loader. Agricultural: Challenger MT965C tractor, Claas Lexion 770 harvester. Military: BAE Systems RG33 APC, Navistar MaxxPro MRAP. Fire trucks: Pierce Arrow XT, E-ONE Cyclone II. Specialty vehicles: Manitowoc 999 mobile crane, Oshkosh M1070 HET (Heavy Equipment Transporter). Marine propulsion: Damen Stan Tug 1606, Sunseeker Manhattan 55 yacht, Viking 55 Convertible, North River 38' Bristol Bay Gillnetter. Industrial: Cat C12-50HZ generator set, Gardner Denver well-service pumps, Sullair 185 air compressors. Variants exist with different ECM calibrations for each application class.
850,000 to 1,000,000 miles before inframe rebuild. The C12 is designed for 850,000 to 1,000,000 miles of Class 8 trucking service before requiring a major inframe rebuild. Industrial and marine applications typically count operating hours rather than miles; the C12 is rated for 15,000 to 25,000 hours of industrial / marine service before rebuild. The keys to C12 longevity are: regular oil and filter changes (every 25,000-50,000 miles for trucks or 250-500 hours for industrial / marine), fuel filter changes at every oil interval, proper cooling system maintenance, periodic EUI injector flow-testing, and avoiding sustained over-fueling beyond Cat-approved fuel maps.
Yes. The C12 is highly rebuildable. Cat rebuild kits are widely available with new pistons, rings, liners, rod and main bearings, head gaskets, valves, EUI injector components, and ancillary components. Cat-certified rebuilders can perform a complete in-frame or out-of-frame C12 rebuild for substantially less than a new engine replacement. Many C12 engines have logged 2,000,000-plus miles or 30,000-plus hours across multiple rebuilds. The EUI injectors and turbocharger are typically replaced or rebuilt separately during major engine rebuild work.
Pre-ACERT C12 (1999-2003) meets pre-2004 EPA standards (no EGR, no DPF). ACERT C12 (2004-2007) meets EPA 2004-2007 standards with EGR and VVA. After 2007, Caterpillar exited the on-highway truck engine market in North America. The pre-ACERT C12 is operable today under grandfather provisions for chassis registered with the engine; the ACERT C12 meets current standards for industrial / marine applications in many jurisdictions but may not be installable as a replacement in a chassis requiring post-2007 EPA compliance. Confirm emissions requirements for your specific application and jurisdiction.
No. There is no core return required.
2 reviews for Caterpillar CAT C12 Engine for Sale | OEM Used 12L Inline-6 Turbocharged Diesel for Class 8 Trucks, Marine, Industrial
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Stanley Q. –
Got a pre-ACERT C12 for a 2002 Freightliner Columbia line-haul replacement. Variant correctly identified as pre-ACERT (not the later ACERT), ECM serial number documented for Cat ET verification, top-end inspection clean, EUI injectors tested. Honest pre-purchase information about the C12’s mid-range positioning between the C9 and C15 (vaz85) and the C13 successor that came in 2007.
Penelope F. –
Sourced a C12 for a CAT 966G wheel loader repower. Donor application correctly identified as construction equipment (not over-the-road truck), ECM calibration documented for construction service, turbocharger and aftercooler condition assessed. Honest pre-purchase information about the C12’s diverse application range and the importance of matching ECM calibration to the construction equipment vs trucking calibration.