Trans Cooler Water Leak...Repairable?

Well, she came to life, and she sprung a leak too. I had the hose on it to run it in the driveway. I noticed a small pin hole leak at the cap seam on the trans cooler. (I think someone didn't drain the water out of the cooler last Fall    I worried about that all winter. Worst fears.... But, it seems the cap just broke away from the body of the cooler. See between the yellow lines.

Can this be welded or brazed? I have a propane torch. Will that get it, or do I need a real welder? I am hoping to heat it and run some solder down in it like when you solder copper pipes together. The body appears to be copper.

Anybody had this happen? How did you fix it?

Ruby fluid (flux) and acid core solder. Do like was said above. Mine was copper. Air test with it under water for leaks.   That will tell you if it is leaking into the oil chamber also.

Thanks for the responses guys! It seems to be air/water tight on the water passage and the oil passages. I think I may have dodged an expensive bullet on this one.

Almost got the old girl ready to go. Doing the other wheel bearing now. Bearings were SHOT! Don't need that break down on the side of the road.

Duane in Indy wrote: A little while ago it was leaking and now miraculously it is not leaking air or water. Did you fix it??   The water flow at that point has no pressure (actually negative pressure). It won't get better on its own. It will start sucking air and give you more problems.   Fix it now or fix it later. Could lead to overheating issues that are hard to find. Still sticking to my choice on fluxes and solders. Sorry Pete

Duane....Not sure I follow you. Earlier today, it had a pin hole leak at the cap/body seam where it was soldered at the factory I used my solder, and flux, using my propane torch, and it seems to have stopped it. At least when I put it in a tub of water and applied air pressure to one end, with the other end plugged. No air leaks. Let me know if I did something wrong. I would rather re-do it now vs. have issues later. Thx!

Thanks Duane, and all! I did not fully explain that I had broken out my trusty torch and solder. My bad! I just thought you guys were so smart you knew what I did!   

Sometimes I am not even sure what I did!