It helps, but I've actually done the equivalent to a running engine. I had an old big block Chevy that I couldn't keep coolant in. I looped the hoses to eliminate the radiator and ran the engine with sodium silicate in it, then drained out the excess. I then loosened the belts and spun the water pump by hand for a while to keep it from locking up.
Worked great!! You need to remember to bypass the heater system as well or you COULD ruin a heater core or heater control valve.
