Welding crack in cast iron central heating boiler

Probably a hopeless task without specialist welding services and as yet I haven't even got the thing to bits to see where the crack is. However if
it's accessible and the whole thing doesn't look paper thin can anyone on here, preferably not a million miles from Slough, have a crack at it? No guarantees obviously but all it's got to do is last another year until I'm out of here and then it's someone else's problem.
Hopefully it might even be in an area where I can screw a plate over it with some sealant but if not I don't care if it's welded, brazed, soldered or even slapped up with chemical metal as long as it'll hold water until after the winter.
Any takers? -- Dave Baker Puma Race Engines www.pumaracing.co.uk Camp USA engineer minces about for high performance specialist (4,4,7)
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Dave Baker wrote:

If it is a small crack, how about trying it with Holt's RadWeld?
Nick
--
Measure twice, cut once.
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Gosh, I remember that stuff. Had a car in the 70s which used that nearly as fast as petrol. Might work for a temporary repair though.
David
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David Littlewood

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David Littlewood responded to

Yes, I think the plot used to be an initial tin of RadWeld, followed by one tin of RadFlush. This was followed by two tins of RadWeld, and two tins of RadFlush. Ad infinitum.
Seriously though Dave, I hope you get your crack sorted out OK..
--
Mike Whittome
The volume of a pizza of thickness 'a' and radius 'z' is given by pi z z a.
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Mike Whittome wrote:

A cheaper solution would be noodle's water.
Nick
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I
Hmmm, that's a thought. Not sure what it would do to the pump and valves in the system though. I'm also not keen on the idea of me trying to bleed radiators and Radweld trying to seal the opening at the same time. -- Dave Baker Puma Race Engines www.pumaracing.co.uk Camp USA engineer minces about for high performance specialist (4,4,7)
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What boiler is it? I had a Baxi cast iron boiler that was leaking and when I pulled it out it was in two halves bolted together with a gasket in between. I put some silicon sealer on it and bolted it back together as a temporary repair while I got the new gasket and it lasted ten years before I had to remove it again and fit the gasket.
--
Regards - Rodney Pont
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Dave Baker wrote:

I would try it with all the radiators disconnected. Me to wouldn't like radweld in the valves.
Decades ago, I also had a crack in the boiler and intended to weld it (with nickel). But I was told that it won't work. You only will get a new crack, except you heat up the boiler (oh, that's what he was made for) quite (say 200°C) and still want to stick your head into it for welding. :-)
Nick
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Dave Baker wrote:

Got any oxygen at hand? I could have a go at silver soldering (or even soft soldering), and I pass by Stroud on the M4 from time to time. Thing is, I use an oxygen generator at home, which is plumbed-in and isn't exactly portable.
'Nother question, mostly for you - I have heard that drag racers use Inconel outlet valves in their engines, and that the top drag people only use them once or twice before replacing them. Some of the used valves are reconditioned and sold, some are sold as-is, and I guess if eg one of a set has broke the rest are junked.
Anyway, my question is, do you know of a cheapish source of such used valves? Will not have to be used in engines, and do not have to be in sets, so unless they are bent or otherwise sort-of-destroyed anything that survived would be of use.
(I want to use them to make turbine wheels with integral shafts for rocket engines - the valve diameter doesn't matter, as the common sizes are all too big anyway, and neither does the shaft diameter or length, again they are more than big enough anyway)
--
Peter


Amoebas are very small
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I
on
I'm
with
after
soft
Ummm, so do I if I'm a very long way from home :)
Thing is, I

Where abouts is home?

Inconel
set
sets,
too
I don't personally know anyone who uses inconel valves in anything. Drag racing at that level is a bit outside my line of country. Nimonic is used in a few standard truck diesel engines though. Would 21/4N austenitic steel exhaust valve material not cope with the temperatures you encounter? -- Dave Baker Puma Race Engines www.pumaracing.co.uk Camp USA engineer minces about for high performance specialist (4,4,7)
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Dave Baker wrote:

I've had good results welding cast with what I believe are called "weldall" stick welding rods. Try asking at your local welding supply outlet. They used to be about £1 each 15 years back :) I understand they contain a large amount of stainless steel? Just grind a nice V in the crack and weld away.
Good luck, Pete.
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