Caterpillar 3306

Engine Specifications & Applications of the Caterpillar 3306 Engine

Overview of the Caterpillar 3306 Engine

The Caterpillar 3306 is a legendary inline 6-cylinder diesel engine known for its durability, power, and exceptional service life. First introduced in the 1970s, the 3306 built upon the success of the 3304 and quickly became one of Caterpillar’s most widely used engines across construction, industrial, marine, and power generation sectors.

Available in naturally aspirated, turbocharged, and turbo-aftercooled configurations, the 3306 could be tuned for various applications requiring up to 400+ horsepower. Known for its mechanical fuel injection system, cast-iron wet-sleeve design, and simple serviceability, the engine became a global workhorse and remains in widespread use today—particularly in rebuild-focused fleets, export markets, and marine operations.

Even though the 3306 was eventually succeeded by electronic models like the C-10 and C-12, it remains one of the most supported platforms in the aftermarket—especially through trusted sources like Diesel Pro Power.

Caterpillar 3306 Engine Technical Specifications

Specification	Details
Engine Model	Caterpillar 3306
Configuration	Inline 6-cylinder, 4-stroke diesel
Displacement	10.5 Liters (638 cubic inches)
Bore x Stroke	4.75 in x 6.00 in (121 mm x 152 mm)
Compression Ratio	16:1 (varies slightly by version)
Aspiration	Naturally Aspirated, Turbocharged, or Turbo-Aftercooled
Fuel System	Mechanical Direct Injection (various pumps)
Cooling System	Water-cooled
Horsepower Range	170–400+ HP @ 1800–2200 RPM
Peak Torque	Up to 1,300 lb-ft @ 1400–1600 RPM
Emissions Standard	Pre-Tier 1 (non-EPA regulated)
Dry Weight	2,800–3,100 lbs (varies by configuration)

Common Engine Variants

• 3306B & 3306C – Later model enhancements with improved block casting and fuel system refinements

• 3306DI – Direct injection variant for improved combustion and fuel economy

• 3306T & 3306TA – Turbocharged and turbo-aftercooled models with increased power output

• 3306 Marine – Custom-configured for propulsion and auxiliary roles with seawater cooling and corrosion protection

Why the Caterpillar 3306 Remains a Popular Engine in the Aftermarket

The CAT 3306 remains in service because of its:

• Long engine life—often exceeding 20,000 hours with proper care

• Fully mechanical design—ideal for remote operations or field service

• Excellent parts support from trusted aftermarket providers

• High torque output at low RPM for demanding applications

• Rebuildability with wet sleeves and robust internal components

Diesel Pro Power supports the 3306 platform with a full line of aftermarket parts engineered to match or exceed OEM performance, backed by our track record of 40,000+ satisfied customers worldwide.

Applications of the Caterpillar 3306 Engine

The versatility and power of the 3306 engine made it a go-to solution across a broad range of industries. Today, it’s especially valuable in repower, overhaul, and heavy-duty applications where downtime is costly and simplicity is key.

1. Construction and Earthmoving Equipment

The 3306 was extensively used in heavy Caterpillar machinery and still powers many of these units in active fleets worldwide.

Common Equipment:

• CAT 966, 970, and 980 wheel loaders

• CAT 140, 160, and 16 motor graders

• CAT 225, 235, 245 hydraulic excavators

• CAT D6 and D7 crawler tractors

• CAT 621, 623 scrapers and coal haulers

Diesel Pro Power stocks engine rebuild kits, turbochargers, cylinder heads, fuel pumps, and other critical components for this fleet of aging but serviceable heavy equipment.

2. Marine Propulsion and Auxiliary Systems

The turbocharged and aftercooled versions of the 3306 were widely used in commercial marine vessels due to their torque curve, long service intervals, and minimal electronics.

Marine Applications:

• Small tugboats and crew boats

• Pilot vessels and harbor workboats

• Commercial fishing vessels

• Marine generators (up to 150 kW)

• Hydraulic winch and pump engines

We provide marine-grade parts, including raw water pumps, exhaust elbows, thermostats, seawater strainers, and corrosion-resistant gaskets for 3306 marine engines.

3. Power Generation and Standby Use

The 3306 was a popular platform for industrial generator sets, especially where continuous duty and high-load capacity were required.

Generator Applications:

• Prime power for remote sites

• Standby emergency power (hospital, telecom, municipal)

• Mobile trailer-mounted generators for rental fleets

• Industrial facilities with 125–300 kW demand

Diesel Pro Power supplies governor parts, sensors, fuel filters, and oil system components to support the 3306 in power generation applications.

4. Industrial, Agricultural, and Oilfield Equipment

The 3306 is used in many types of heavy-duty, engine-driven industrial systems where torque and fuel efficiency are critical.

Common Installations:

• Water pumps for irrigation and dewatering

• Drill rigs and frac pumps

• Industrial air compressors

• Belt-driven conveyor systems

• Grain elevators and feed systems

With its reliable power delivery and ease of field maintenance, the 3306 continues to be trusted in harsh environments and remote regions.

Additional Resources

Marine CAT 3306 Component Maintenance Life