Used 3406B CAT Engine for Sale | OEM Used Caterpillar 3406B Mechanical 14.6L Inline-6 Turbocharged Diesel
$12,000.00
At a Glance
- Condition: OEM used, compression tested across all 6 cylinders
- Availability: In stock, 1980 to 1987 era 3406B cores available
- Shipping: Free shipping to all 50 states via crated freight, 7 to 14 business days
- All 6 cylinders compression tested, results available before you pay
- Mechanical generation confirmed (NOT 3406E electronic, NOT 3406C sleeve metering)
- ATAAC (air-to-air aftercooled) configuration verified
- Cat pump mechanical fuel system inspection documented
- Cylinder head crack inspection
- Cam gear wear inspected
- Donor application documented (Kenworth, Peterbilt, Freightliner, Mack, International, Western Star)
- 100% fitment verified before every order ships
- No core charge required
- Backed by a 15 day replacement warranty against internal defects
Description
About the 3406B CAT Engine
The Caterpillar 3406B Engine is the engine that powers a generation of heavy-duty equipment and vehicles. We here at Part Nests offer a high-quality used 3406B Cat Engine for sale, this comes with our assurance of excellent performance and value for your equipment needs.
About the 3406B Cat Engine for Sale
The Caterpillar 3406B Cat engine is a 14.6-liter, In-Line 6-cylinder diesel engine renowned for its robustness and exceptional performance. Widely used in heavy-duty trucks, construction equipment, and marine applications, this engine provides a reliable power source with impressive durability. The 3406B Cat engine typically delivers around 350 horsepower in standard tune and can reach up to 525 horsepower with the right configurations, all while running the legendary mechanical fuel injection system that pre-dates the electronic 3406E.
Critical: 3406B is NOT the same as 3406E
The Cat 3406 family went through several distinct generations during its long production history. This listing is the 3406B mechanical generation, NOT the 3406E electronic generation. Buyers researching “3406” should understand the differences:
| 3406A | 1973 to 1980 | Mechanical | First-generation 3406. In-line mechanical pump, no aftercooler |
|---|---|---|---|
| 3406B (THIS LISTING) | 1980 to 1987 | Mechanical | Updated mechanical pump, ATAAC aftercooler added, refined power ratings up to 525 hp |
| 3406C | 1988 to 1993 | Mechanical | Sleeve metering mechanical fuel system, refined emissions, transitional generation |
| 3406E | 1993 to 1998 | Electronic | First electronic 3406, HEUI fuel system, ECM-controlled, sold separately as our vaz61 listing |
| C15 | 1998 to 2003+ | Electronic | Successor to 3406E, ACERT later variants |
The 3406B and 3406E are different engines. ECM electronics, fuel system, mounting, and ancillary systems differ. If you are searching for the 3406B specifically (mechanical generation), this is the right listing. If you are searching for the 3406E (electronic generation), see our separate 3406E CAT Engine listing (vaz61).
Performance and Applications of Caterpillar 3406B Engine
The 3406B Cat Engine has a big reputation among industrial diesel engines because of its high performance and bullet-proof mechanical durability that is hardly matched by anything else.
- Great for transporting heavy-duty applications like Class 8 trucks, construction equipment, and marine vessels
- Boasts capabilities such as the high power density (up to 525 hp from 14.6L) and reasonable fuel-efficiency for the era
- Pre-emission compliance means no DEF, no DPF regen, no SCR aftertreatment, dramatically simplifying long-term ownership
Why Buy a Used Caterpillar 3406B Engine
- Reliability: Developed for high-strength, heavy-duty service. Cat designed the 3406 family for 1,000,000-plus mile service between major overhauls.
- Power: Available in power output of 350 to 525 hp for various applications. Owner-operator builds typically run 425-475 hp ratings.
- Versatility: Used in countless Class 8 trucks, construction equipment, marine, and industrial applications.
- Cost Efficiency: Cost-effective compared to new engines while delivering proven longevity. Particularly valuable as the pre-EGR mechanical generation cannot be reproduced new (modern emissions standards prohibit clean-sheet mechanical engine development).
- Robust Construction: The CAT 3406B engine is widely noted for strength, deliberately designed to serve demanding use in trucks, industrial applications, marine, and similar heavy-duty environments.
- Inline 6-Cylinder Configuration: The 3406B uses an inline 6-cylinder layout providing excellent power balance and fuel economy. The arrangement is characterized by low vibration and smooth running.
- Turbocharged with ATAAC: All 3406B engines are turbocharged with Air-to-Air Aftercooler (ATAAC) charging configuration, which charges the air before sending it into the cylinders, helping in better combustion and yielding better horsepower. This is a critical specification, the 3406B is NOT naturally aspirated despite some confusing references; turbocharger plus ATAAC aftercooler is standard.
- Mechanical Fuel System: Engine control on the 3406B uses a mechanical fuel injection system. This is the key differentiator from the later 3406E electronic generation. The mechanical system is simpler and more field-repairable, particularly attractive for owner-operators in remote service areas where electronic component diagnosis and parts availability can be challenging. Mechanical components also age more gracefully, the 3406B fuel pump and injection components have proven service life measured in millions of miles.
Compatibility of Caterpillar 3406B Engine
The 3406B Cat engine has very wide application across vehicles and machinery. Confirm your specific application spec list before ordering. It can fit:
- Heavy-Duty Trucks: Peterbilt, Mack, International, Western Star, Freightliner, and Kenworth
- Construction Equipment: Caterpillar Wheel Loaders, Caterpillar Motor Graders, Caterpillar Bulldozers, Caterpillar Excavators, and Caterpillar Scrapers
- Industrial Equipment: Generators, Pumps, Air Compressors, Crushers, and Compactors
- Marine Applications: Commercial Fishing Boats, Tugboats, Barges, Yachts, and Workboats
- Agricultural Equipment: Large Tractors, Harvesters, and Sprayers
- Specialty Vehicles: Fire Trucks, Heavy-Duty Ambulances, Utility Trucks, and Service Trucks
- Mining Equipment: Caterpillar Mining Trucks, Large Wheel Loaders, and Underground Mining Equipment
- Logging and Forestry Equipment: Skidders, Feller Bunchers, and Log Loaders
Why a 3406B over a 3406E or C15
- Mechanical simplicity: No ECM, no electronic injectors, no sensor-driven fuel control. Field repair without specialized electronics.
- Pre-emission: No DEF, no DPF, no SCR aftertreatment. Lower long-term operating cost.
- Owner-operator appeal: The 3406B is the natural drivetrain for restorers and operators of vintage Kenworth W900, Peterbilt 359/379, Freightliner Classic, Mack RD/CL chassis from the early-to-mid 1980s.
- Mechanical pump rebuilding: Cat-experienced shops can rebuild the mechanical fuel pump and injectors indefinitely. Electronic replacement parts for the 3406E are increasingly scarce.
Here at Part Nests, you will find the Used 3406B Cat Engine for Sale at competitive pricing, our goal is to make your quest for a heavy-duty diesel engine seamless. This Used 3406B Cat Engine has been put through a series of tests including oil analysis, compression testing, and condition verification.
What Ships and What Does Not
| Item | Details |
|---|---|
| INCLUDED | Long block: cast iron block, crankshaft, pistons, connecting rods, camshaft, cylinder head, valve train, oil pan, front timing cover, gear train, mechanical fuel injection pump (typical), mechanical injectors (typical), valve covers. |
| NOT INCLUDED | Turbocharger (sold separately when condition warrants), aftercooler / ATAAC core (chassis-mounted, not engine-mounted), wiring (3406B is mechanical, minimal electrical), exhaust manifold, starter, alternator, A/C compressor, water pump (typical), accessory drive bracketry. |
| Fluids | Drained before shipping. Refill with 15W-40 CK-4 (or equivalent) heavy-duty diesel motor oil, approximately 12 gallons. |
| Core Note | No core charge. You are not required to return your old engine. |
Vehicle Compatibility
The Cat 3406B was used in:
| Vehicle | Compatibility |
|---|---|
| Kenworth W900, K100, T800, T600 | 1980 to 1987 (Cat-equipped variants) |
| Peterbilt 359, 379, 362, 377 | 1980 to 1987 (Cat-equipped variants) |
| Freightliner FLT, FLC, Classic | 1980 to 1987 (Cat option) |
| Mack CH, RD, CL, DM | 1980 to 1987 (Cat option, Mack also offered Mack EM7 / E6 / E7 engines) |
| International 9300, 9370 | 1980 to 1987 (Cat-equipped) |
| Western Star 4900, 5900 | 1980 to 1987 (Cat-equipped) |
| Construction Equipment | Cat 988, 980, 950 wheel loaders; Cat D8, D9 dozers; Cat 14G, 16G motor graders; Cat 631, 633 scrapers; various other Cat machines |
| Industrial Generators | Cat 3406B-powered prime power and standby generators |
| Marine Vessels | 3406B marine variants powering commercial fishing, tug, workboat, and yacht applications |
| Mining Equipment | Cat haul trucks and mining equipment from the era |
Inspection Workflow
Every used 3406B Cat we ship goes through this process:
- Compression test across all 6 cylinders, pressure per cylinder recorded
- Cylinder head inspected for cracks
- Cam gear wear inspected
- Mechanical fuel pump function verified
- Mechanical injector spray pattern inspected (where pulled for inspection)
- Liner condition inspected through bore
- Front gear train wear assessed
- ATAAC connection points inspected
- Oil cooler condition inspected for coolant cross-contamination
- Generation confirmed (3406B mechanical, NOT 3406E electronic)
- Donor application photographed and documented
- Approximate hours / mileage documented when verifiable
Where donor mileage is verified, it is shared. Most 3406B cores have logged 700,000-plus miles, which is normal for an engine designed for 1,000,000-plus mile service.
Why Buy From Part Nests
- All 6 cylinders compression tested, results before you pay
- Cylinder head crack inspection
- Cam gear wear inspected (a critical heavy-mileage 3406B concern)
- Mechanical fuel pump function verified
- Generation explicitly confirmed (3406B mechanical, NOT 3406E electronic)
- ATAAC turbocharged configuration verified
- Donor application documented (Kenworth, Peterbilt, Freightliner, Mack, International, Western Star)
- Free crated freight to all 50 states, no hidden fees
- No core charge, keep your old engine
- 15 day replacement warranty on internal defects
- Call (240) 306-7051 to confirm generation (3406B mechanical vs 3406E electronic – see vaz61 for the electronic listing), ATAAC configuration, and chassis fitment before ordering
15 Day Replacement Warranty
Every used 3406B Cat 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)
- Cam gear failures within 15 days from installation (where gear was documented as in-spec at shipping)
- Mechanical fuel pump failures within 15 days from installation (where pump was documented as functional at shipping)
- Connecting rod, lifter, or bearing failures within 15 days from installation
- Incorrect generation shipped (3406B vs 3406A vs 3406C vs 3406E) 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 (15W-40 CK-4 spec heavy-duty diesel oil recommended)
- Damage from operating with incorrect coolant or neglected cooling system
- Damage from over-fueling tune (cranking the mechanical fuel pump beyond Cat-approved fuel maps)
- External components (turbocharger, ATAAC core if separately documented, exhaust manifold, starter, alternator, A/C, water pump, accessory drive bracketry) unless itemized
- Labor expenses of any kind
To start a warranty claim, reach us within 15 days of delivery at (855) 634-4447.
- All 6 Cylinders Tested: Compression results documented before payment
- Cylinder Head Crack Inspection: Critical heavy-duty diesel wear point assessed
- Cam Gear Wear Inspected: Heavy-mileage 3406B concern evaluated
- Mechanical Fuel Pump Verified: Cat pump function tested before shipping
- Generation Confirmed: 3406B mechanical (NOT 3406E electronic - see vaz61)
- 15 Day Replacement Cover: Internal defects protected from delivery onward
Additional information
| air-intake | Turbocharged and Air-to-Air Aftercooled (ATAAC) |
|---|---|
| bore-x-stroke | 5.4 in x 6.5 in |
| compression-ratio | 14.5:1 |
| coolant-capacity | 10 gallons |
| cooling-system | Water-cooled |
| engine-model | 3406B |
| engine-type | Four-stroke, In-line 6-cylinder diesel engine |
Four generations of the Cat 3406 spanning 1973 to 1998-plus. The 3406A (1973-1980) was the first-generation 3406 with in-line mechanical pump and no aftercooler. The 3406B (1980-1987, this listing) added ATAAC air-to-air aftercooler and refined the mechanical pump and power ratings up to 525 hp. The 3406C (1988-1993) introduced sleeve metering mechanical fuel system as a transitional generation toward emissions compliance. The 3406E (1993-1998) was the first electronic 3406 with HEUI fuel system, ECM-controlled injection, and is sold as our separate vaz61 listing. The C15 (1998-2003-plus, with ACERT variants later) is the successor to the 3406E.
Field repairability, pre-emissions simplicity, and parts availability. The 3406B uses a fully-mechanical fuel injection pump and mechanical injectors. There is no ECM, no electronic sensors, no sensor-driven fuel control. Field repair is possible with conventional mechanical tools without specialized electronics. The 3406E uses HEUI (Hydraulically actuated Electronic Unit Injector) electronic injectors that require Cat ET diagnostic software for service, electronic parts that are increasingly scarce as the platform ages, and a more complex repair workflow. For owner-operators in remote service areas, or for restorers of vintage 1980s Class 8 trucks, the mechanical 3406B is significantly more attractive.
Air-to-Air Aftercooled. The 3406B uses an Air-to-Air Aftercooler (ATAAC) configuration where the turbocharger compressed air is cooled by an air-to-air heat exchanger (typically chassis-mounted in front of the radiator) before entering the cylinders. ATAAC is more efficient than the older water-to-air aftercooler designs used on the earlier 3406A. The cooler intake charge increases air density, improving combustion efficiency and power output. All 3406B engines are turbocharged with ATAAC; the 3406B is NOT naturally aspirated despite some legacy references.
Class 8 conventional cab tractors and vocational trucks from 1980 to 1987. Most commonly: Kenworth W900, K100, T800, T600 (Cat-equipped variants); Peterbilt 359, 379, 362, 377 (Cat-equipped); Freightliner FLT, FLC, Classic (Cat option); Mack CH, RD, CL, DM (Cat option, alongside Mack EM7 / E6 / E7 engines); International 9300, 9370 (Cat-equipped); Western Star 4900, 5900 (Cat-equipped). Also found in Cat construction equipment (988, 980, 950 wheel loaders; D8, D9 dozers; 14G, 16G motor graders; 631, 633 scrapers), industrial generators, marine vessels, and mining equipment of the era.
350 to 525 hp depending on programming. The 3406B was offered in multiple power ratings throughout its 1980-1987 production. Common ratings: 350, 375, 400, 425, 450, 475, 500, and 525 hp. The 425-475 hp range is common in owner-operator builds. The 500-525 hp ratings are popular for heavy-haul and over-the-road applications. We document the original factory rating where verifiable. The mechanical fuel pump can be calibrated for different power outputs by Cat-experienced shops.
Yes for grandfather provisions, no for current model year requirements. The 3406B was manufactured before modern EPA emissions standards took effect (EGR mandate 2002, DPF mandate 2007, SCR/DEF mandate 2010). Trucks equipped with 3406B engines from the 1980s era are operable today under grandfather provisions in most jurisdictions, particularly for owner-operator and vocational use. However, the 3406B cannot be installed in a new chassis as a replacement engine if the chassis emissions certification requires post-2002 emissions standards. The 3406B is appropriate for: vintage truck restoration (original chassis), pre-emission grandfather use, off-road industrial/marine/mining applications, and equipment categories not subject to on-highway emissions standards.
Yes, the 3406B is highly rebuildable. Cat rebuild kits are widely available with new pistons, rings, liners, rod and main bearings, head gaskets, valves, and ancillary components. Cat-certified rebuilders can perform a complete in-frame or out-of-frame 3406B rebuild for substantially less than a new engine replacement. The mechanical fuel pump can also be rebuilt indefinitely by Cat-experienced fuel pump shops, with new plungers, barrels, and metering components. The 3406B was designed for 1,000,000-plus mile service between major rebuilds, and many engines have logged 2,000,000 to 3,000,000 miles across multiple rebuilds.
No. There is no core return required.
2 reviews for Used 3406B CAT Engine for Sale | OEM Used Caterpillar 3406B Mechanical 14.6L Inline-6 Turbocharged Diesel
Related products
Rusty O. –
Got a 3406B for a vintage 1985 Kenworth W900 owner-operator restoration. Mechanical generation correctly identified (3406B, NOT the later 3406E electronic), all 6 cylinders compression tested, cylinder head crack inspection clean, cam gear wear inspected. Mechanical Cat pump function verified. Honest pre-purchase information about the 450 hp rating, pre-emissions ownership advantages, and the cross-link to vaz61 for buyers wanting the electronic 3406E.
Bridget N. –
Sourced a 3406B for a vintage 1986 Peterbilt 379 long-haul restoration. ATAAC configuration verified, donor application from a similar Cat-equipped Peterbilt, mechanical fuel system documented. Honest pre-purchase information about the 3406B vs 3406E generation distinction and the mechanical field-repairability advantage for owner-operator builds. Foundation for keeping the vintage rig on the road.