Stop in for a cup of coffee

Or when they leak internally and the diesel runs away.
I had that happen on the dyno cell on a customers truck. You don’t know scary sounds until a 2000 hp pulling engine with 3 giant turbos fully spooled runs away. Luckily the boss man was able to grab an old metal coffee can and shove over the inducer housing to cut off air or it would have been a big boom