From 1961 until 2001 the 4017 sat outside, exposed to the harsh Wisconsin winters. As luck would have it, the Union Pacific took great steps to preserve the locomotive. They put a protective layer of a foam-like material in the firebox and in the smokebox to reduce the likelihood of rusting. They also applied two large covers over the massive smoke stacks. These efforts kept the innards of the beast well preserved, but the boiler jacket was not removed. Eventually the Museum had the boiler jacket removed. This decision protected the exterior of the boiler from severe rusting from constant water contact.