Water in a radiator cannot get hot enough to melt solder. You will not ever see that. If the radiator was plastic then some crack around the neck below the radiator cap developed and finally blew. If it was metal then it was a very RARE blow off of a neck on a radiator. Many things had to conspire and be wrong at the same time. The cap shold have released the pressure LONG before the neck was damaged. Hoses should have blown before the neck was damaged. etc etc. This is an odd one at best. Probably more to the story of course & no way to know ...
Several things to report:
1. The mechanic who works on my car told me how to drain the radiator - drain plug at the bottom. (Of course, the drain plug fell into the jar, but it won't be to hard to get it out.)
2. He told me about 4 bolts to remove the radiator - turns out there are only two needed to remove it, but of course, all the shrouding needed to be removed first, as well as the hoses, one of which had to be cut.
3. Successfully removed the radiator.
4. He told me about a nearby radiator repair shop where I'll take it within the next couple of days.
5. Although the place where the filler neck came off the radiator was shiny yesterday, today it's dull. Must have oxidized overnight. It's been rainy.
6. JWR, I agree that it's very strange that it got hot enough to melt the solder. There must have still been water in the radiator when it blew because there was a huge cloud of steam when it did blow. Could be that the radiator cap didn't release pressure properly, but just before it blew, the pressure relief tube was whistling, releasing steam. So perhaps the connection between the neck and radiator was weak. I don't remember how long ago the radiator was replaced, but i'm sure it was less than 10 years. Perhaps the radiator repair guy will have some ideas.
Thank you everyone for your thoughts and comments.
