Tugboat Engines


Model 251

This three-quarters cutaway view of a sixteen cylinder ALCO 251 engine was featured in the manufacturers brochure for their Century Series diesel locomotives. The marine version of the engine normally has a deeper oil pan. Artwork produced by ALCO Products around 1964.



The American Locomotive Company (ALCO) originated from the mergers of a number of steam locomotive manufacturers, and by the early 1900s had developed into one of the largest locomotive builders in the world. Their main factory was located in Schenectady, New York and the company also maintained offices in New York City.

ALCO's product line was much larger than just locomotives, they were also a builder of industrial products including pipe, heat exchangers, springs, and oil industry supplies. By the late 1920s they were one of the leading builders of diesel engines in the US, through the efforts of their subsidiary McIntosh & Seymour, located in Auburn, New York. M&S built large, slow speed Diesel engines in a variety of sizes, and also built 12-1/2 inch bore by 13 inch stroke medium speed engines for railroad and marine applications. They were a pioneer in the turbocharging of Diesel engines, and by World War Two their engine product line included six and eight cylinder engines in both turbocharged and non-turbocharged variations, for marine, rail, and industrial service. This product series included the high-base Model 538 engine (marine, stationary and locomotive), the low-base Model 539 engine (marine and locomotive), and the welded block Model 540 engine (US Navy and other marine applications), as well as a variety of other Diesel engines both larger and smaller. An ALCO Model 539 engine is shown in the advertisement below.

By the middle of the war, their existing engine product line was overtaken in horsepower output by several other builders, particularly Electro-Motive Division of General Motors, and Fairbanks-Morse. This led ALCO into a development program for higher RPM Diesel engines with 8 inch bore and 10 inch stroke. After several years of experimentation ALCO introduced their Model 244 engine in early 1946. This engine was widely produced in locomotive applications during the rush to Dieselize the railroads after World War Two, but it proved troublesome in its early years, and although ALCO solved the problems, they realized that a more durable engine with higher horsepower potential was needed. The Model 251 was introduced in 1951, and was a completely different design from its predecessor.

Over the course of many years of service in the marine, railroad, and industrial markets, the Model 251 proved to be a successful and durable engine. Although US sales of the engine dropped off after ALCO's exit from the US locomotive market and closing of the Schenectady plant in 1968, the Model 251 remained popular with overseas customers, particularly in Asia and South America. The Model 251 new engine production and replacement parts business was subsequently acquired by Bombardier and then GE, before being sold to Fairbanks-Morse, who presently continues to build the engine.

Although many of the locomotives that originally used the Model 251 have reached the end of their economical service lives and have been scrapped, the removed engines often find a useful second life in the marine and industrial markets. Replacement parts for the engines are still being manufactured by Fairbanks-Morse, insuring that some of the remaining fleet of Model 251 engines will continue to operate for many years in to the future. The nearly six decade long production run of this engine is impressive, but falls short of the Fairbanks-Morse OP engine, which passed its 70th year of production in 2008.

Article and page design by Preston Cook, ©2009 by T.E.S.




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