employ a steam engine to crack a nut

all it's cracked up to be

As good as claims or reputation would suggest.

blow off steam

To vent; to talk or take action (especially in a ranting or unrestrained way) so as to relieve stress.

bust a nut

To ejaculate.

crack a crust

To make a living.

crack a fat

To get an erection of the penis.

crack a smile

To smile, especially while attempting not to.

crack down

To take harsh action (against), as when enforcing a law more stringently than before.

crack of dawn

The first moment of daylight; the instant at which sunrise begins.