Kyle, if your radiator is leaking at the lower hose fitting, it might just need a solder repair that you can do on your own. If the leak is at the hose fitting, it is from the lower tank and not the core. That would be great news for you and an easy fix.
Here is a tip that I learned when helping at my uncle's radiator repair shop as a kid. If you are going to do solder work on either the upper or the lower tank, you need to keep the radiator full of water up to the level that you are working to protect the solder joints connecting the core to the tanks. That is easily accomplished by plugging whatever inlets/outlets are necessary (I use Oatey pressure test expansion plugs available for a couple bucks at the plumbing department of any Home Depot or Lowes) and filling the radiator with water up to at least the core/tank seam. Be sure the tank/core seam closest to your work is covered with water. If you can angle the radiator to keep water against any other solder joints that might be on the tank that has the leak, do that to protect them. Just make sure that you don't have water up against the area that you need to repair. If working on the upper tank, the radiator is right side up. If working on the lower tank, the radiator is upside down.
Find the leak. Use sandpaper to clean the brass around the leak really well. Make sure that there is no paint left and that the brass is very shiny. Apply regular plumbing flux to the area. Use a propane torch (or a micro-torch if it is a pin hole leak) to heat the area and use regular plumbing solder to repair it. When it is hot enough, the solder will flow beautifully. If it bunches or beads, it is not hot enough. Be careful to isolate the heat the the leak spot to avoid melting other solder joints on the tank.
It it is just a pin hole leak or a small crack, the solder itself should do the trick. It it is a large leak or a gash, make a repair patch out of thin copper and form it to the contours of the repair area. Copper is soft and forms to shape easily. Don't be afraid to form it with a hammer if necessary. Use solder to tin both the contact side of the patch and the repair area on the tank. Once both pieces are tinned, apply flux and solder the patch in place.
This can also be done with an acetylene torch, but I recommend propane if you aren't used to doing these repairs with the hotter acetylene torch.
Since you filled the tank and covered the tank/core seams with water, you will not loosen those solder joints. Since the water is not touching the area of the repair, it will not impede soldering by cooling the area.
If you are ready to scrap the radiator anyway, there is no harm in trying.
Send me a PM if I can help,
Matt
