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The Caterpillar 3406 is one of CAT’s most iconic heavy-duty diesel engines. Designed for marine, industrial, and generator applications, this inline 6-cylinder platform is known for its long service life and ease of maintenance. Diesel Pro Power is proud to support the original version of the 3406 — excluding later B, C, and E series — with a complete inventory of high-quality aftermarket parts. All components are in stock and available for worldwide shipping within 24 hours. Complete in-frame and out-of-frame kits Includes pistons, liners, rings, wrist pins, rod and main bearings, and full gasket set Designed for long-term durability and factory-spec compression recovery Oil pressure, coolant temperature, tachometers, voltmeters, and boost gauges Mechanical and electric options for marine and industrial panels Compatible senders available Replacement water pumps with cast impeller Includes gaskets and bolts for installation Maintains coolant flow and operating temperature Raw water pumps for saltwater or heat exchanger setups Bronze impellers and marine-grade seals Available as complete assemblies or rebuild kits Aftermarket cylinder heads for the original 3406 Available fully assembled with valves, springs, guides, and seats Milled and inspected for proper sealing and combustion Mechanical fuel pumps and priming systems Fuel shutoff solenoids, injection hardware, and return lines All components designed to meet factory flow and pressure Unit injectors compatible with original CAT 3406 timing and spray pattern Includes O-rings, seals, and installation clamps Designed for clean atomization and consistent delivery Direct replacement turbochargers Options for standard duty and high-flow marine versions Includes turbo gaskets, oil lines, and mounting hardware Charge air coolers for turbocharged engine configurations Marine and stationary options Includes gaskets and mounting brackets Oil pumps, pans, dipsticks, and coolers High-capacity flow matched to original engine specs Includes gaskets and oil pressure regulators Balanced and magnaflux-inspected crankshafts Available in standard and undersize journals Includes thrust washers, front/rear seals, and keyways OEM-profile aftermarket camshafts Includes cam bushings, lifters, followers, and thrust hardware Precision-matched to original fuel and valve timing Complete piston sets with rings, wrist pins, and circlips Standard and oversize pistons available Engineered for factory compression and fit Forged connecting rods with pre-installed bushings Compatible with factory piston and crankshaft setups Remanufactured and new options available Exhaust manifolds (wet/dry), elbows, mufflers, and turbo outlets Marine-rated components built for corrosion resistance Includes flange kits, clamps, and heat-shield gaskets Full engine gasket kits (top and bottom end) Head gaskets, valve cover, intake/exhaust, oil pan, crank seals Heat- and oil-resistant materials suitable for marine and industrial use Oil pressure switches, temperature sensors, shutdown solenoids, ignition switches Compatible with marine panels and alarm systems Marine-safe, sealed contacts available 12V and 24V gear-reduction starters High-output alternators with internal or external regulation Solenoids, voltage regulators, and mounting brackets Primary and secondary spin-on or cartridge filters Fuel/water separators, filter heads, and mounting hardware Designed to protect injectors from particulate and moisture contamination OEM-fit spin-on oil filters High-capacity filtration for extended service life Filter bases and bypass adapters available Push-pull throttle and shift cables for marine control Stainless steel core and low-friction jacket Compatible with standard marine levers Heavy-duty control cables for throttle or clutch operation Saltwater-resistant jacket and sealed ends Designed for rugged marine use Cables for industrial throttle, PTO, and governor control Available in various lengths and end configurations Suitable for generators, pumps, and remote panels High-temperature Caterpillar yellow enamel Gasket adhesives, thread sealant, anti-seize compounds Marine-safe and oil-resistant formulas Twin Disc marine transmission parts & rebuilt transmissions Couplings, damper plates, PTO adapters, and clutch assemblies Compatible with CAT 3406 engine-to-gearbox connections Trusted by over 40,000 customers globally All parts are aftermarket, engineered to OEM-quality standards Fast 24-hour global shipping Clean navigation and expert technical support  The Caterpillar 3406 is a mechanically governed, inline six-cylinder diesel engine that debuted in the mid-1970s and quickly became one of Caterpillar’s most iconic platforms. Before the evolution into the B, C, and E series, the original 3406—also known as the Pre-B model—established a reputation for mechanical simplicity, robust performance, and dependable torque in heavy-duty operations. Built for power and serviceability, the early 3406 featured a dry cylinder block, direct injection fuel system, and mechanical fuel control. The engine was designed with a broad operating window and delivered consistent horsepower at various RPM ranges. While later variants added electronic fuel control and emissions compliance, the original 3406 remained a pure mechanical workhorse, ideal for marine, industrial, and power generation use. Even decades after its introduction, the original 3406 is still in service around the world—especially in applications where Tier compliance is not mandatory and reliability is paramount. Specification Details Engine Configuration Inline 6-cylinder, 4-stroke diesel Displacement 14.6 Liters (893 cubic inches) Bore x Stroke 5.4 in x 6.5 in (137 mm x 165 mm) Compression Ratio 14.5:1 to 15.3:1 (varies by build and rating) Aspiration Options Turbocharged or Turbocharged with Aftercooler Horsepower Range 250–475 HP @ 1,800–2,100 RPM Max Torque Range 800–1,300 lb-ft @ 1,200–1,600 RPM Fuel System Mechanical Unit Injector Cooling System Water-cooled Emissions Compliance Pre-Tier / Non-regulated Dry Weight (approx.) 2,700–3,000 lbs Dry cylinder block with no liner flanges—designed for rigid strength and rebuild efficiency Gear-driven camshaft and accessory drive—eliminates belt failure concerns Modular fuel and air systems for easier service in the field Mechanical injection system—fully serviceable without electronic diagnostics Long service intervals and rebuildable bottom end (crank, rods, liners) The 3406’s platform stability, high torque output, and mechanical architecture made it a favorite among diesel mechanics and operators seeking control, durability, and uptime. The original CAT 3406 was deployed across a wide spectrum of demanding industries. Its high displacement and mechanical dependability gave it a central role in powering vessels, generators, and industrial machinery. These engines were typically used in conditions where load stability, fuel economy under heavy use, and ease of mechanical servicewere critical. The 3406 was one of Caterpillar’s most widely used engines in marine environments. Known for its ability to hold torque under load, the 3406 powered both propulsion systems and onboard auxiliary machinery. Coastal cargo vessels, harbor tugs, and push boats Shrimp boats and commercial fishing trawlers Workboats, pilot boats, and patrol vessels Hydraulic pump drives and marine fire suppression systems Marine generator sets in the 125–250 kW range Operators preferred the original 3406 for its excellent low-end torque, essential for pushing heavy hulls and operating in adverse sea conditions. Many of these engines are still in use on the water today, often as part of repower projects for vessels originally equipped with less efficient or harder-to-service engines. In industrial use, the 3406 engine was a mainstay of heavy-duty stationary and mobile equipment, especially in oilfield, mining, and construction sectors. Drilling rig engines and mud pump drives High-volume irrigation and dewatering systems Mining auxiliary power units Portable and skid-mounted compressor stations Conveyor belt power units in large-scale quarry operations The 3406’s broad torque curve and rugged build made it ideal for continuous-duty industrial work, particularly in environments with fluctuating loads and long operational cycles. The original 3406 was widely used in diesel-powered generator sets, where its displacement and mechanical stability provided clean, dependable power across a wide output range. Prime power for off-grid operations (oil camps, mining, telecom) Emergency backup for hospitals, industrial facilities, and data centers Mobile generator trailers used in disaster recovery and infrastructure support Generator sets in marine engine rooms or shipboard auxiliary systems Output ratings for 3406-powered generators typically ranged between 200–300 kW, depending on configuration and application. Operators chose the 3406 when reliability and fuel efficiency under load were top priorities. The 3406 also played a role in agricultural settings, where high-horsepower diesel power was required for belt-driven systems, large equipment, and irrigation setups. High-lift diesel water pumps for flood irrigation Diesel power for crop dryers and feed mixers Large grain elevators and conveyance systems Belt-driven agricultural processing machinery Stationary engines used on sugar cane and rice farms Its mechanical design made it especially desirable in rural or remote farming operations, where access to diagnostic tools or electronic parts was limited. The original 3406, thanks to its pre-emissions mechanical setup, is frequently repurposed in repower projects around the world. The engine remains ideal for fleets operating in areas without stringent emissions laws. Marine vessels converting from obsolete Detroit Diesel or Cummins platforms Exported generators for emerging markets Utility trailers and pump units for developing regions Custom-built heavy equipment requiring dependable diesel power Many operators specifically seek the 3406 due to its robust aftermarket support, ease of overhaul, and ability to run cleanly on varied fuel quality without DEF, EGR, or DPF systems. The original Caterpillar 3406 engine continues to be respected worldwide for its mechanical integrity, torque-rich performance, and field-serviceable architecture. Its long-running production life and wide application range prove its value across the marine, industrial, generator, and agricultural sectors. Today, the 3406 remains a go-to choice for operators who value engine rebuildability, fuel efficiency under load, and the ability to operate without electronics. Whether it's powering a fishing trawler or generating electricity at a mining camp, the 3406 has proven itself to be one of Caterpillar’s most trusted engine designs. For operations that demand dependable mechanical power with zero compromise, the Caterpillar 3406 delivers—then and now. Marine CAT 3406 Component Maintenance Life Everything You Need to Know About the Caterpillar 3406 Marine Engine
Parts for Caterpillar 3406
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Aftermarket Parts for the Original CAT 3406 Engine
Engine Overhaul Kit for Caterpillar 3406
Gauges for Caterpillar 3406
Engine Water Pump for Caterpillar 3406
Marine Water Pump for Caterpillar 3406
Cylinder Head for Caterpillar 3406
Fuel Components for Caterpillar 3406
Injectors for Caterpillar 3406
Turbo for Caterpillar 3406
Intercooler / Aftercooler for Caterpillar 3406
Oil System Components for Caterpillar 3406
Crankshaft for Caterpillar 3406
Camshaft for Caterpillar 3406
Engine Piston Kit for Caterpillar 3406
Connecting Rod for Caterpillar 3406
Exhaust for Caterpillar 3406
Gasket Kits for Caterpillar 3406
Sensor & Switch for Caterpillar 3406
Starter & Alternator for Caterpillar 3406
Fuel Filter for Caterpillar 3406
Oil Filter for Caterpillar 3406
33C Marine Cable (3/16") for Caterpillar 3406
43C Marine Cable (1/4") for Caterpillar 3406
Industrial Cable for Caterpillar 3406
Paint & Sealant for Caterpillar 3406
Twin Disc Transmissions That Pair To The Caterpillar 3406
Why Diesel Pro Power?
Engine Specifications & Applications of the Caterpillar 3406 Engine
Overview of the Original Caterpillar 3406 Engine
Caterpillar 3406 Engine Specifications (Original Version)
Notable Design Features
Applications of the Caterpillar 3406 Engine
1. Marine Propulsion and Auxiliary Power
Common Marine Applications:
2. Industrial Equipment & Heavy-Duty Power Units
Industrial Equipment Applications:
3. Generator Sets (Prime and Standby Power)
Power Generation Uses:
4. Agricultural and Utility Applications
Agricultural Applications:
5. Global Repower & Export Use
Common Repower Scenarios:
Final Thoughts
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Additional Resources
The Legacy of the Caterpillar Marine 3406 Engine: A Retrospective
