LONGBOX55 mentioned in an old thread once about drilling and tapping a hole and threading in a pipe plug. Grind down, drill half through the plug and tap. Insert another pipe plug. Repeat down the entire stitch. Of course it also depends on where the crack is located...
For some reason that always seemed like an ingenious way to handle it. In my defense, it was several years ago and my memory doesn't quite remember.
Not to mention the fact that the search feature sucks no matter how hard I try to use it and with whatever combination of words I use I can't find that thread...
Jeff