[eagle]

I've sealed much worse than that crack. Drain the coolant, then as others have said, drill the ends, V it out just a bit, then put a thin layer of the standard JB weld. After that is cured, add more layers to build it up. The JB Quick isn't as strong in my opinion however if you are getting too much sag on the second coat, the JB Quick sags less so that is an option. You can also cover the uncured JB with tape to keep it from sagging. I use a small grinding wheel to shape it when its cured for a few days then prime and paint. If your careful even you won't be able to find the crack. I would sandblast the area to be JB welded to give is a better adhesion. It is kind of a pain getting sand all over everything so cover well.