Written By, Mike McGlothlin
CAT 3304
History
If you cut two cylinders off the venerable CAT 3306 you get the CAT 3304 engine—a tough-as-nails, simple, and fuel-efficient diesel engine easily capable of lasting 15,000 operating hours between overhauls. Like the 3306, the CAT 3304 has powered America for more than half a century. The 3304 features a 4.75-inch bore, a 6.00-inch stroke, a gray iron block and head, and ductile iron (and induction hardened) wet sleeves. Its displacement checks in at 425 cubic inches, or 7.0L and it can be had in either naturally aspirated or turbocharged form, with available CAT 3304 turbo configurations expanding its performance range. These foundational details make up the core CAT 3304 specs that defined its long production life.
Common Applications
While the CAT 3304 isn’t as widely known or renowned as its bigger brother (the 3306), it fit the mold perfectly in smaller machines and equipment. You can find the 3304 reliably humming away in rollers, dozers, excavators, skidders, and a host of other construction applications, as well as in countless gen-sets and stationary power equipment. It’s also a proven workhorse in the marine industry. Power ratings vary from as low as 63 hp in naturally aspirated form to as much as 203 hp in turbocharged configurations.
Production Run
Production of the CAT 3304 began alongside the 3306 in the 1970s and it quickly earned a reputation for durability. To ensure every 3304 was fit for the field, the sea, or any other possible condition, Caterpillar hot-tested every 3304B on the engine dyno before allowing it to leave the factory. All 3304’s are of the direct injection variety and come equipped with an inline mechanical (scroll type) injection pump and externally accessible fuel injectors (i.e. above the valve cover). Depending on its specific configuration, the CAT 3304 weighs between 1,600 and 1,800 pounds.
How It’s Remembered
Like the CAT 3306, it’s highly durable. Without a doubt, there are countless 3304 engines, scattered all over the world, still chugging along four decades after having left the factory assembly line. On top of its industry-topping durability, the CAT 3304 is incredibly easy to service. And by that we don’t mean changing the oil and fuel filters. Running the valves on a 3304 is as easy as it gets, and the water pump’s impeller, bearings, and seal can all be serviced without disturbing any coolant lines (or other gear-driven accessories). It’s easy to maintain, easy to work on, and still enjoys very good parts and product support.
Sources:
Big Bear Engine Company
https://www.4btengines.com/cat-3304-engine/
3304B, 3306B Brochure
