Thread: Soldering copper radiator tank

I haven’t done one for 30 years but last time I used a 1” solid copper plumbers iron heated by blowtorch, and used the blowtorch directly for plenty of pre-heat. I used 60/40 electronics solder with a bit of extra bakers fluid flux. I drained first and washed/flushed thoroughly afterwards.

If I were doing it now I’d use oxy and 15% silver, but that doesn’t work so well on plastic so I suspect it’s a skill I won’t use again.

Thanks Brad. Not sure about my chances with an 80W soldering iron if you needed a blowtorch...

A electric soldering iron will not be enough
.If the crack or metal is the slightest bit dirty will make it difficult.
People who still do this sort of thing usually.try and sand blast the spot to be soldered in a cabinet blaster.
Professional repairers usually use grades of solder not normally available to the layman.
It's not impossible to fix in situ....................but a big plumbers copper iron and blow torch is minimum.

Fair enough, seemed worth asking. Thanks for the guidance everyone. I wonder if a plumber would do it? Blowtorch and a copper iron is a bit too much of a tool investment for what is probably a one-off job.

I would take it out and to a Old school radiator shop to repair.
I am lucky to have such a place here in Northern NSW.

whitehillbilly

The other aspect to consider is why is there a crack in the first place? If on a soldered join no problem just resolder but if a crack in the actual metal then why there? If you just solder over the crack will most likely be back - will need a patch soldered over it.

I have had success using a hot air gun to preheat the whole area and keep it hot while soldering. As mentioned above, the whole join needs to be scrupulously clean, and for most cracks you should consider patching with sheet copper or brass. Note that the radiator is brass not copper.

The top of the radiator tends to last longer if you don't use it as a seat or support when working in the engine bay.
.W.