Yes, that crack is absolutely enough to fill the sump.
You can work it out roughly, assume it "drips" once per second, its actually a weep, it takes roughly 20 drips to make a 1 m/l, so that's 3 m/l a minute, x 60 mins = 180 m/l hour.
So very roughly in 33 hours running, you will fill the sump...