Can you solder a radiator?

I just got my GDI 3 core radiator installed, and on the way to school I noticed that I'm leaking coolant from the lower radiator hose. No big deal I figured, I'll just need to tighten the hose clamps a little. I go to pull the overflow hose off so I can remove the bottle and POP, off comes the fitting for the hose from the filler neck. I'm going to call the place I ordered it from, and see what they will do, but if they say I did it, and it wasn't flawed, can I just solder the fitting back on? I have the brazing skills of a 2 year old, but I've been racing RC cars since I was about 6, and I'm pretty handy with a soldering iron.

Ah, not with a normal electric iron you won't, you need a blue wrench. Sounds like a cold solder joint, the cause is probably that the two surfaces were not heated enough before solder was applied. A propane with a fine tip like a plumber uses will work but I'd get a replacment from the manufacturer. Don't explain the circumstances or go into any detail that might give them an 'out', just tell them that it came off, end of discussion.

So say you used a blue wrench to assemble some copper tubing to make coolant lines on a Samurai they shouldn't melt apart then, right? I guess I'm more concerned with the melting point of solder than my ability to stick things together.

GDIs have a lifetime warranty, I believe. Take it back where you got it and have them make it good.

Eagle is absolutely right. Take the radiator back and ask for a replacement under the GDI lifetime warranty. Merely attaching or removing the overflow hose in a customary manner can't be construed as abuse or neglect, so I don't see how the seller or GDI can argue the breakage would not be covered. The poor factory brazing is simply a manufacturing defect. On the other hand, if you goober the weld by trying to braze it back together yourself, the cause of the breakage (poor factory brazing) could be obscured.

Plus no telling if the same guy was learning on your radiator and the other joints are not too sound...

Honestly it dosen't look like that joint was brazed at all. There seems to be a crimp on the end of it where it fits into the neck, and I can't just push it back in. I still have a couple days until classes end for the semester, and then I'm going to pull it and send it back. I'll be at the beach for a week anyway, so not having wheels won't be a problem. Just as long as everything is back up and running the weekend before NAC Fest so I can do some testing, I'll be happy as a clam. So far, other than the fitting falling off, this whole cooling project has worked out pretty well, although it hasn't really been that hot out yet.

Without any doubt, take it back. Just like someone said. Tell them it came off. No details if they ask what happened, just say, "I opened the hood and it was off. I want a replacement."

Good luck.