Detroits, at least the old ones, had a big huge mechanical door in the blower/ intake that you could slam shut with a cable in case of runaway. Some diesels can do this if they get too much fuel --or oil --where it can be sucked into the intake. I don't know anything about your tractor or your problem, but I'd sure as HECK figure a way to plug the air intake TIGHT until you get this nailed.