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Introduction and Development
The Caterpillar 3306 is a legendary inline-six diesel engine introduced in the 1970s as a replacement for older models 1673 and 3160. Its 10.5-liter (638 cubic inch) displacement and robust design quickly made it a workhorse in construction, mining, and industrial applications. The first significant installation was in the CAT 225 excavator in 1973.
Technical Specifications
The Caterpillar 3306 diesel engine is a cornerstone of industrial and heavy equipment powertrains from the 1970s through the 1990s. Its mechanical simplicity, combined with rugged construction and versatility, ensured widespread use in powerful Caterpillar machinery and industrial applications. Though replaced by modern diesel designs due to stricter emissions and electronic controls, the 3306 remains emblematic of durability and user-friendly maintenance in heavy engine history.
The Caterpillar 3306 is a legendary inline-six diesel engine introduced in the 1970s as a replacement for older models 1673 and 3160. Its 10.5-liter (638 cubic inch) displacement and robust design quickly made it a workhorse in construction, mining, and industrial applications. The first significant installation was in the CAT 225 excavator in 1973.
Technical Specifications
- Engine Type: Inline 6-cylinder, naturally aspirated or turbocharged versions available
- Displacement: 10.5 liters (638 cubic inches)
- Bore x Stroke: 4.75" x 6" (121mm x 152mm)
- Firing Order: 1-5-3-6-2-4
- Valve Lash: .015" intake (cold), .025" exhaust (cold)
- Torque Specs: Rod torque roughly 30 ft-lbs + 90 degrees; head torque varies with bolt size
- Power Output: Early models around 270 hp, varying with version and applications
- Wet liner construction allowing easier rebuilds and enhanced durability
- Mechanical fuel injection with variants including indirect injection (PC), direct injection (DI), and turbocharged/intercooled (DITA) versions
- Non-electronic, purely mechanical systems known for reliability and straightforward maintenance
- Widely used in medium to large earthmoving machines such as excavators, dozers, and graders
- Also saw extensive use in trucks, marine vessels, and industrial generators
- Known for longevity, with many units running for 30+ years when maintained properly
- Known to have troubles with water pump shafts and front oil seals over extended service life
- Valve dropping typically occurs only after very high hours or mishandling
- Regular overhaul kits are available ensuring restoration to original performance levels
- The 3306 was largely phased out by the mid-1990s due to evolving emissions regulations and advances in diesel technology
- It was succeeded by engines like the Caterpillar 3176 and the newer C10, C12, and C13 series
- The 3306 still holds a reputation for durability and ease of rebuild unmatched by many modern electronically controlled engines
- Wet Liner: Removable cylinder liners replaceable during overhaul, extending engine block life
- Indirect Injection (PC): Fuel injection first into a pre-combustion chamber
- Direct Injection (DI): Fuel injected straight into combustion chamber, increasing efficiency
- Torque: A measure of rotational force, vital for heavy equipment performance
- Valve Lash: The clearance between valve components, adjusted to ensure proper engine breathing
The Caterpillar 3306 diesel engine is a cornerstone of industrial and heavy equipment powertrains from the 1970s through the 1990s. Its mechanical simplicity, combined with rugged construction and versatility, ensured widespread use in powerful Caterpillar machinery and industrial applications. Though replaced by modern diesel designs due to stricter emissions and electronic controls, the 3306 remains emblematic of durability and user-friendly maintenance in heavy engine history.
