Why do they run the diesel and not the steam locomotive to the South Rim in the winter time?

Question

Why do they run the diesel and not the steam locomotive to the South Rim in the winter time?

Answer 1

I didn't know they did that now. Used to be steam all year round. If I had to speculate though, I'd say the steamers are suffering from too much wear from daily use. And probably too much money is required to maintain them. So they are reserved for summer when ridership is high, and more people are on each train to appreciate them.