So if it isn't leaking it has already been repaired satisfactorily. :fing32:
Putty & paint the area if the sight of it keeps you up at night.. :dunno:
The actual reason is that once the water in the block froze & then expanded..
It pushed towards the point of least resistance from the expansion point.. As the inside areas of the block have the cylinders a bit more support it tends to push the outside first as that is usually the easiest route. If you have a chance to look at the block from the top (head) side you will see what I'm rambling on about.. Here's one:
http://www.wengers.com/parts/Farm-T...Engine-Gas/Sub/CYLINDER-BLOCK/01-6010C_8N.htm
The large holes between the cylinders are the water jacket and water (& anti-freeze hopefully) surround them and is contained by the block's outer jacket. The round metal disk @ the bottom front side below the dipstick of the block is a 'freeze-plug' which is supposed to push out and relieve that pressure but it must have been blocked off by more ice. The location of these nowadays is towards the top sides (~1/4 to 1/2 way down from top of block) of almost any engine I've worked on. **Must be bottom of the block wasn't the best place to put them huh? :sorry1: Mr. Ford
I'll hazard a guess that your "H" shaped braze repair is around one of the raised circles on the sides of the block as the openings of the water jacket is supported by metal from the cylinders to the block sides by a strip of metal and the jacket's open spaces are largest there..
The outside of the block isn't
always where they leak though.. Sometimes the cylinders crack and then then water goes everywhere.. It's truly an unsettling sight to see foam emitting from the crankcase vent / oil filler cap shortly after an engine starts.. :Stop: :banghead3 :duh:

isgus: :crybaby:
It can be a heck of a lot more expensive than a little braze & time to fix that one as a block replacement could have been necessary.. So the PO of your 'N' got lucky!!! :trink40:
Enjoy your 'N'! :goodl: