A total of 1,260 were built for
American railroads before the
SD45-2 replaced it in 1972, along with the related
SD45T-2 'Tunnel Motor'.[citation needed]
SD45s had several teething problems. Reliability was not as high as anticipated; the twenty-cylinder prime mover was prone to
crankshaft failure from engine block flex. Though it produced 600 horsepower (450 kW) more than the 16-645E3 in the
SD40, some railroads felt the extra horsepower wasn't worth it, even after EMD strengthened the block to eliminate crankshaft failures. At low speeds, when tractive effort was adhesion-limited, the SD45 provided no advantage over the SD40.[citation needed]
February 20, 1989, Southern Pacific SD45R locomotive #7502 was involved in a wreck that derailed 48-cars of an 82-car train and three of these cars had contained residue from
chlorine,
phosphoric acid and
hydrocarbons.[3]
On May 12, 1989, Southern Pacific SD45R locomotives #
7551 (formerly #8985) and #7549 (formerly #9038) were both destroyed in the
1989 Cajon Pass Runaway when they crashed along Duffy Street in
San Bernardino, California.[4]
In 1981, the
Southern Pacific Transportation Company had rebuilt a single SD45 (SP SD45 #8837) into a single locomotive model designated the SD44R and numbered it #7399.
The
Southern Pacific Transportation Company had rebuilt a total of 167 EMD SD45 units into EMD SD45R
diesel locomotives at their own Sacramento Shops under the Southern Pacific's M-99 rebuild program and renumbered their units as 7400 through 7566. Most of them in their SD45 form were classified by the Southern Pacific as EF636-1, EF636-2, EF636-3, EF636-4, EF636-5 and EF636-6, but when they were all rebuilt under the Southern Pacific's M-99 rebuild program, they were classified as EF636LR-1, EF636R-2 and EF636LR-3.[7]