Radiator repair

I filled the cooling system on 7c242 for the first time and was less than impressed when a Radiator I used that Looked very good leaked big time.The water was runing down from the top like a water fall and I could not pinpoint the spot. I removed the radiator and moved it to the work bench to investigate. I made plates to plug off the ports and piped in 20 psi of compressed air.It leaked so much it felt like I had a fan blowing on me. As it turn out most of the solder Joints connection the tubes to the top flange were bad. Now I am trying to reason out why just the top would have this issue? I am not sure if this has alwayse been in the top possition or if it got turned over.Anyway I heated and removed the top flange and cleaned things up, Now looking for advice for reinstalling the top flange, Having a plumbing back ground I have soldered a thousand or more pipes but nothing like this. Has anyone done this. any guess as to why this happened?

That's a big job!

Clean, Clean and clean some more!

Then set it up square all the way across, flux it and solder 4 tubes on the corners to hold it while you start working your way across.

Or just order another core!

I expect the joints at the top were exposed to air when the level of coolant was low.

Any chance it's been in a fire?

my 2 cents worth,,, i just had 3 radiators from a 22 in a rad shop 3 weks ago, one passed the boil and leak test but before that, two of them failed , their top and bottom tubes leaking at the plates.... They suggested that i diassemble the cast parts,,, then bring him back the core (he would do the disassembling , but with the twisted off bolt potential, I thought it best to do it myself rather than pay him 80 and hour to do it),,, then they would dip the ends of core in acid to clean it (extremely clean!!!! it has to be ),,, then he would flux the tubes where they needed solder ,,, then he would dip the whole bottom of the core into a pool of molten solder (presumably in a huge tank!) side note:these guys are set up to do Huge V-16 diesel radiators from railroad locos and such... I am sure there is an outfit like that reasonably near everyone, if you ask around. Then he would reassemble the top and bottoms and/ or sides and pressure test it...8 psi i thought he used for an unpressurized system like i had. He cautioned that occasionally if the core is rotten or too far gone the acid bath will kill it for good,,, (however nothing ventured, nothing gained).....and it will not work, he quoted that he could clean and dip and reassemble my looe parts for like 250.. labor included,,, which is a better number than the 500 or more for a new core, plus the labor for the reassemble and pressure test... on mine the core tubes are 3 and four layers deep ,, so I would not advocate trying to fix it yourself,, what if one inner core leaks how do you get at it?.... Vibration is what loosens the soldered tube/plate joints... good luck and hope this helps,,, you can call me if you like and i can give you the outfits name and number and you could call them with questions about their procedure... my number is 920-210-2875 Happy new year ,,, dave P