[Bring_Back_Shantz]

Well if there is a crack that goes completely through the foundation wall you may have a MUCH bigger problme than just water seepage.

If it is only a small crack on the outter surface you should be okay to just patch it up (make sure you do a good and thorough job as any water getting in will just make the crack worse once it gets cold again). But if you think you actually have a crack right throuh, it's definatly worth taking a peek as it may be a sign of something much much worse.