The Caterpillar 3304 is a heavy-duty, 4-cylinder diesel engine designed for durability, longevity, and versatility. Originally introduced in the 1960s and used extensively through the 1980s and 1990s, the 3304 engine has proven itself in countless applications—from construction equipment to marine auxiliary power. As part of Caterpillar’s 3300-series family, which also includes the 3306 and 3304B variants, the 3304 features a mechanically governed direct injection system, a wet-sleeve design, and an option for turbocharging depending on configuration. With its reputation for mechanical reliability and low-maintenance operation, the CAT 3304 remains popular today in fleets committed to overhaul and parts replacement rather than new engine purchases. Even though the engine is no longer produced by Caterpillar, the aftermarket parts ecosystem remains strong—especially through suppliers like Diesel Pro Power, which specialize in premium-quality 3304 components. Specification Details Engine Model Caterpillar 3304 Configuration Inline 4-cylinder, 4-stroke diesel Displacement 7.0 Liters (425 cubic inches) Bore x Stroke 4.75 x 6.00 inches (121 mm x 152 mm) Compression Ratio 16:1 (varies by version) Fuel System Direct Injection (Mechanical) Aspiration Naturally Aspirated or Turbocharged Cooling System Water-cooled Rated Horsepower 95–150 HP (Turbocharged up to 170+ HP) Max Torque ~420 lb-ft @ 1,400–1,800 RPM Operating Speed 1800–2200 RPM Dry Weight Approx. 1,400–1,600 lbs (depending on version) Emissions Compliance Pre-Tier 1 (non-EPA regulated) 3304NA – Naturally aspirated for standard-duty applications 3304T – Turbocharged for improved power and torque 3304DI – Direct injection for enhanced fuel efficiency 3304B – Later version with performance and emissions improvements 3304 Marine Engine – Equipped for auxiliary or propulsion use with seawater cooling and corrosion protection Simple mechanical design—ideal for field service and rebuilds Wet replaceable cylinder liners—extend engine service life through in-frame overhauls Turbocharging options for improved output without increasing engine size Reliable direct injection system for consistent power delivery Proven performance across thousands of installations worldwide These advantages make the 3304 a popular engine platform for operators seeking long-term ROI through rebuild and parts replacement, rather than costly upgrades or replacements. Thanks to its robust design and flexible power output, the Caterpillar 3304 found widespread use in multiple industries. Today, it remains in operation in marine, construction, agricultural, and power generation applications, especially where simplicity and serviceability are key. The 3304 was widely installed in Caterpillar and non-Caterpillar construction equipment, where torque and uptime were essential. CAT 920, 930, 950 wheel loaders CAT 112 and 120 graders CAT 931, 933, 951 track loaders CAT D4 and D5 dozers (early models) CAT 225 and 235 hydraulic excavators Air compressors, trenchers, and skid units In these applications, the 3304 offered dependable torque, ease of service, and long hours between overhauls. Diesel Pro Power supports these machines with rebuild kits, injectors, turbos, and more. Though less common in full propulsion, the turbocharged Caterpillar 3304T was used in smaller vessels and as an auxiliary engine. Marine generators (up to 75–100 kW) Hydraulic power units for cranes and winches Bilge, ballast, and fire pump engines Light-duty commercial boats (harbor tugs, crew boats) Auxiliary drive systems for refrigeration and deck gear Diesel Pro Power stocks marine-ready raw water pumps, heat exchangers, thermostats, and gaskets tailored to 3304 marine configurations. The Caterpillar 3304 excelled as a standalone power source for various stationary and mobile units in industrial operations. Portable water pumps and flood control equipment Drilling rigs and hydraulic power packs Generator sets (up to 100 kW depending on configuration) Oilfield service units Railroad maintenance equipment Its compact size, mechanical simplicity, and consistent performance made it an excellent choice in harsh environments. Many early agricultural tractors and irrigation systems used the 3304, especially in large-scale farming operations or for powering auxiliary equipment. Diesel-powered irrigation pumps Grain elevators and conveyors Stationary belt-driven equipment Early Challenger and Massey Ferguson tractors (select models) Diesel Pro Power supports agricultural users with affordable overhaul kits, fuel components, and cooling system replacements.
Parts for Caterpillar 3304
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Engine Specifications & Applications of the Caterpillar 3304 Engine
Overview of the Caterpillar 3304 Engine
Caterpillar 3304 Engine Technical Specifications
Notable Engine Variants
Key Features of the Caterpillar 3304 Engine
Applications of the Caterpillar 3304 Engine
1. Construction & Heavy Equipment
Equipment Powered by CAT 3304:
2. Marine Auxiliary and Light Propulsion
Marine Use Cases:
3. Industrial Equipment and Power Units
Typical Installations:
4. Agricultural Equipment
Agricultural Applications:
Additional Resources