Need Input On Resoldering Radiator Petcock

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  #1  
Old 12-06-09, 10:58 AM
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Need Input On Resoldering Radiator Petcock

I need input on fixing a radiator. What I need to do is resolder the petcock bung back in the lower tank. When I was attempting to drain the radiator the petcock and bung its threaded into came out of the tank. I'm able to clean the mating surfaces but I'm not sure how to fix it.

Its on a car I plan to sell so I don't want to spend very much money on it.

I've been told I might be able to resolder it using a high watt soldering gun. I know too much heat using something with a flame like a propane torch will probably cause problems because it will be too heat.

I'm wondering whether a butane soldering iron with its higher non flame output will work? Anybody ever done it with one? What solder should I use?

Also wondering if a two part epoxy like JB weld might work?

Any input or advise is appreciated.

Dom
 
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Old 12-06-09, 11:32 AM
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you have a radiator with metal tanks still? Most any I have seen for quite a few years have plastic tanks.


If you do have a metal tank, it will take much more heat than a soldering iron of any type I have ever seen will produce. A rad shop uses a torch similar to an oxy-acetylene set-up.

If you know of any pro plumbers, if they have a turbo torch with either acetylene or propane, that would be adequate.

Obviously you do have the concern about too much heat and melting the solder that holds the tank on but that is why radiator shops were a viable enterprise: knowledge and experience
 
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Old 12-06-09, 12:25 PM
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nap,

Yes the radiator is from a 1971 car and is metal.

Radiator shops were a viable enterprise until the introduce of aluminum radiators with plastic tanks. Now, the few remaining radiator shops just want to replace radiators not fix them. Three out of four of the local radiator repair shops where I live have closed, and the fourth one has a terrible reputation. I have a oxy-acetylene set-up but not the touch required to fix a radiator which is why I'm looking for a friendlier low tech and cheap solution.

I asked about soldering with a soldering iron because a mechanic friend of mine said he's done it that way a few times with good results but its time consuming.

Any thoughts on using JB weld?

Dom
 
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Old 12-06-09, 12:51 PM
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maybe have your friend do it for you. I have never seen an iron big enough to solder a radiator. The radiator does what it was intended to do too efficiently, it cools.

By the time the area you are working on is hot enough to sustain molten solder, the heat has also traveled far enough to soften other soldered areas as well. You need to be able to contain the heat to the work area so that means enough btu to heat it quickly, before it soaks into adjacent areas and get the intended work done quickly or;


If you know anybody that does bodywork, they may have some heat sink putty. Can't remember what a name brand but it is kind of like a mix of clay and sawdust and is wet. It acts to stop the heat from traveling beyond where it is placed. A quick look for the stuff turned up one site where a guy recommended using Play Doh for the purpose. I don't know how it would work but it may be something to consider.
 
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Old 12-06-09, 01:53 PM
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I've seen electric irons big enuf...prob weighed 3-4 lbs and would trip a 15A circuit There were also some that were heated in a oven or by a torch..they were even more massive. I guess they were used to solder some sort of sheets of copper? wasn't my area...

I really think you need to find an old timer who used to do this and see what he says...I wouldn't use JB weld.
 
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Old 12-06-09, 03:43 PM
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35 years ago I remember that the drain that was on mine was some kind of brass alloy material and I ended up just brazing it on to the tank with a hot enough hardware store blow torch (mix of propane and something else) when I was driving my first $200 ride. All the skill I needed then was what I learned just by doing it. Once hot enough the brass flowed like solder. I remember that lead solder was used in the day by the rad shops to seal up minor leaks around the copper fins wasn't it.
 
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Old 12-06-09, 05:11 PM
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Originally Posted by Gunguy45 View Post
I've seen electric irons big enuf...prob weighed 3-4 lbs and would trip a 15A circuit There were also some that were heated in a oven or by a torch..they were even more massive. I guess they were used to solder some sort of sheets of copper? wasn't my area...

I really think you need to find an old timer who used to do this and see what he says...I wouldn't use JB weld.
yep, got one of the 3-4 pound electric irons. Has a tip on it about 1" diameter or so. Still tough to solder anything like what we are talking about. The heat is pulled away pretty quick by the thin copper, or whatever, of the tank. It has a hard time keeping up.

It's really hard to beat a flame for soldering rads.

if anybody has one of the micro torches, I think that would work quite well.

if/when you do this, be sure the metal is clean and you use a good acid flux on the metal. Tinning the individual pieces where they fit together before actually trying to solder them together would probably help you as well.
 
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Old 12-06-09, 07:42 PM
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A regular plumbers propane torch will do the job. You need some 40/60 acid core solder, some muratic acid, and a brass bristle brush. Heat the area slightly, dip the brush in some acid, and brush vigorously, be sure to get all the paint off, area to be soldered must be clean. After cleaning the radiator and the bung fit them together, apply heat to one side of the bung while holding the solder to the other side, as soon as the solder runs pull the heat away, but keep feeding the solder until there is enough liquid solder to run all the way around the bung. If the area has been properly cleaned the solder will run all the way around the bung, and seal it in properly. If you are concerned about loosening other joints from excessive heat, you can put some shop rags on the closest seams and pour water on them before you solder. After the cleaning the whole repair should not take longer than 2 or three minutes.
 
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Old 12-06-09, 08:24 PM
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Originally Posted by wire twister View Post
A regular plumbers propane torch will do the job. You need some 40/60 acid core solder, some muratic acid, and a brass bristle brush. Heat the area slightly, dip the brush in some acid, and brush vigorously, be sure to get all the paint off, area to be soldered must be clean. After cleaning the radiator and the bung fit them together, apply heat to one side of the bung while holding the solder to the other side, as soon as the solder runs pull the heat away, but keep feeding the solder until there is enough liquid solder to run all the way around the bung. If the area has been properly cleaned the solder will run all the way around the bung, and seal it in properly. If you are concerned about loosening other joints from excessive heat, you can put some shop rags on the closest seams and pour water on them before you solder. After the cleaning the whole repair should not take longer than 2 or three minutes.
in 'my' experience-this is as close as you will get t a fix.
the problem lies in the fact that the 'inside' of the tank is dirty!
that is why a radiator shop (that do not exist any more) would remove the tank/ clean it/ repair it & reinsall it)
when you start heating the tank, the inside crud will foul the solder joint.
'if' as stated above you use enouhg time to 'clean' the joint on the inside-it might work.
good luck
 
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Old 12-07-09, 03:53 AM
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Last year I had to do some major work to my tractor. When removing the radiator the top tube came loose. I can't solder for beans but I gave it a try anyway. I don't remember if I used propane or my oxy/acetylene. Too start off with I got it too hot and had to dig some solder out of the radiator Anyway I did a halfway decent job but it had a pin hole leak so I JB welded it and it's held up fine. I agree that JB alone probably wouldn't be a good idea.
 
  #11  
Old 12-09-09, 08:01 AM
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Here are a few soldering basics that apply to radiators:

1. The surfaces must be free of scale and oxide. Sand down to bare metal. The solder won't wick if the surfaces are tarnished.

2. Use flux. Rosin is best. This is applied on clean untarnished metal.

3. All surfaces must be up to temperature. Solder will not wet or wick into a surface that isn't heated to a proper temperature. This is where a torch will do a superior job over an iron.
 
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