Radiator material

Brass is an alloy of copper and zinc
Bronze is an alloy of copper and tin, maybe some other elements too.
As such, copper being the primary metal, lead/tin solder will bond to either one of them - IF - it is clean!

"Clean" may require the use of strong acids and that can be hazardous both from dermal burns and inhalation of the fumes, especially when heated.
I knew a "radiator man" that said in extreme cases he had used Nitric Acid - that is a very dangerous and life threatening product in several ways but it was very effective when the others did not work.

Some radiator cores may be of aluminum or other metals. As such, they may not respond to solder as we commonly know lead/tin alloys.

If you have a few tubes leaking and you heat excessively as in melting Brazing rod - are you going to defeat your original purpose and warp the plate or de-bond the other tubes?

You might consider some of the "cold" based modern epoxies if they are suitable for the application.

CTS

Hi All,
Some of the early radiators are made of steel as I have a few on my machines.

Regards

get a product called ezi-weld fluid 801 its zinc chloride based for normal use you use it at 4 to 1 for hard to solder like monel or stainless use it neat.

the secret in soldering is have clean material and heat it properly over heating actually cuases problems too.

if you get the core hot tanked it will clean it up properly.

thanks guys, going to get back to it this weekend when I get some of my other crap done I will let ya know how she goes.

Heat source?
Oxy-Acetylene is in most cases is way too hot and difficult to control, especially on thin materials.
Propane (LPG) & Mapp gas is more friendly to soldering. MAPP is hotter (more BTU's)

Years ago, the common practice was to use Soldering Irons ( actually COPPER) that were heated, tinned and used for the heat source.
Very effective when used properly and there is no open flame involved in the actual soldering process. They are now difficult to find, maybe flea or swap meet for starters.
Sal Amonniac (spelling) was used to help clean and tin the copper.

I would suggest if you have not done much soldering, you practice on some scrap materials and gain some competence before tackling a radiator with multiple soldered joints.
Remember CLEAN surfaces and that solder will always run toward the heat.

Solder comes in several forms, each with their own general uses. Acid Core - general work, Rosin Core- electrical and Solid bar or wire (no flux)
There are also different alloys, 50/50 being quite common.
For use in copper plumbing, lead free is now mandatory and it too uses special fluxes and care.

CTS