You may dodge the bullet on a cracked block if there's plenty of airspace for the coolant to expand to if it freezes. In a closed system, the last place to freeze is where the cracks happen, as the frozen water blocks the expansion. A 55 gallon drum full of rainwater will bulge the bottom, as that's the last spot to freeze. If there was a trace of antifreeze in it still, you'll likely be OK. A 32% solution of ethylene glycol will get you down to zero Fahrenheit.
Last edited by klhansen; 11/13/2019 11:44 PM.
