Alco 250 engine

[CPM500]

Invention of the Marketing Dept. to draw focus away from the '244' handle

• serrated mains
• hardened, forged crank
• snubber valves
• nodular iron heads
• improved (new design) exhaust manifold

Ultimately, the issue with the engine was that it produce hp in excess of the safety margins allowed for the lower end (diameter of crankshaft mains was too small and block was too flexible.

[NorthWest]

Yes, it was also known as the 244H. The RSD-7s were the first to have it.

[Leo_Ames]

It's an upgraded Alco 244 with a new designation due to issues with the 244 that were souring opinions on it. I believe that an aftercooler is the primary feature that differentiates it from a normal 244. 

[DS4-4-1000]

In some material I have read on the Reading's RS3s there is mention of a replacement diesel engine that ALCO developed to be a direct replacement of the troubled 244.  It was called a 250 and the Reading installed 250s in several RS3s and one FB1. 

Can anyone tell me exactly what is a 250 and what makes it different from a 244 and from a 251?  I expect that the normal ALCO nomenclature was used for the name.  That is "2" specifies the cylinder bore and stroke and "50" specifies the year the engine was accepted.