Cracked a cast iron radiator, trying to repair it.

[Archiethere]

Overtightened a bush for a cast iron radiator and cracked it.. Going to try and fix it with epoxy, the crack gets wider when I tighten the bush. Would you apply the epoxy when the crack is “open” or “closed”?

https://imgur.com/gallery/lsAXaEb

Long story with this radiator and I don’t want to give up with it haha. Worth a go tying to repair it.

 

[footprints]

To be honest I think you are on a hiding to nothing with that, job for a pro, welding cast is very difficult.
However if you "feel lucky" I would fill the crack open then remove the bush allowing it to close up then put a strap of steel bent to fit over the crack side to side and set it in epoxy. Then after fully cured refit the bush using Fernox LSX which does not require strangling up tight like PTFE or Hemp.

 

[Archiethere]

Thanks mate, unfortunately you were right! The crack must’ve gone all the way into the thread inside, I used epoxy and it worked ok for the most part but some of the crack was inaccessible. Lesson learned! Will look into fernox though, thanks for your help

 

[Burnerman]

I’d try brazing that one with oxy acetylene, using a large nozzle and reducing flame....it can be perfectly successful if you can find someone with the correct gear.
John

 

[Harry Bloomfield]

I’d try brazing that one with oxy acetylene, using a large nozzle and reducing flame....it can be perfectly successful if you can find someone with the correct gear.
John

I have electric welded cast in the past - I managed to crack my welding vice 20 years ago, welded up and it has been fine since. The whole casting needs to be heated, to get a successful weld.

 

[Burnerman]

I’ve managed to repair cast iron planes and even early mini rear trailing arms with bronze welding / brazing....using a huge nozzle the area was hot enough to allow the spelter to flow.
Tried to electric weld a cracked cylinder block once....made a right arse of it
John

 

[Lower]

I have electric welded cast in the past - I managed to crack my welding vice 20 years ago, welded up and it has been fine since. The whole casting needs to be heated, to get a successful weld.

Can't really do that with a cast iron rad because the gaskets between the sections won't be able to take the heat you need.

Brazing or soldering would be the best way to fix that crack. Grind the crack wider so that you can get a decent amount of braze into the break so that it doesn't just sit on the surface.

 

[Captain Nemesis]

https://imgur.com/gallery/lsAXaEb