Well half power of a fully operational steel steam engine is 16 KU/t based on my theory, so it would still run, but might have trouble with certain ores.
Try this, run a strong bronze steam engine and see if it can power a bronze crusher. It’s max is 384 steam/t so it’s going to take a bunch of boilers but according to my theory is should produce 48ku/t at its upper limit which is ample to run the crusher, if I’m wrong it’ll overload.
At 384 steam/t you’ll need 8 bronze boilers or I think 2 strong bronze boilers.