Years ago a Detroit Diesel engine rep came to our shop for a yearly engine info update. He brought up the fact that in his travels he sees diesel mechanics now and then starting an engine momentarily after a re-assembly or whatever with absolutely no coolant. He stressed even for a few seconds very high combustion heat is created with absolutely no way for it to dissipate whatsoever. After thinking about it later, makes perfect sense. First, due to the trapped heat with nowhere to go, most all piston ring tension is probably quickly shot. Can't do exhaust valves much good either. And sure enough, there was a guy, among others, on U-tube who ran an engine on a stand for a good 2 minutes, zero coolant, then a few weeks later he was asking why all the blue/white exhaust smoke and oil consumption (bad rings, duh) . There's an "expert" on FTE with a video right now proudly firing one up with no coolant, (same guy just grenaded one of his rebuilds after 60 miles but that's another story). Point is, just because you see some Clown do something on U-tube to his IDI diesel doesn't mean it's the right thing to do.