Cast Iron Cistern weeping

[DIY-JC]

Hello all.
I've just fitted an old cast-iron bell type cistern. After being in a week it has developed a weep in the cast iron at the bottom shelf , not the bell reservoir. It's only a small weep which you can't see a hole when you wipe it dry.
My plan is to use JB Waterweld to "weld" a sheet of galv steel/aluminium down onto the entire shelf on the inside, then use some sealant around the edge to "belt and brace" it.
Does anyone have any other ideas on what might work or if my plan would work?

Cheers

 

[polesapart]

Not heard of "waterweld" but recommend CT1 or Fernox LSX for this kind of bodge.

Clean surfaces well first!

 

[Lower]

Try leaving it for a month or two. Cast iron will sometimes rust itself water tight.

 

[DIY-JC]

Not heard of "waterweld" but recommend CT1 or Fernox LSX for this kind of bodge.

Clean surfaces well first!

Bodge? How very dare you. I'll let you know this is top-quality fudging.
Waterweld - https://www.jbweld.com/product/waterweld-epoxy-putty

 

[DIY-JC]

Try leaving it for a month or two. Cast iron will sometimes rust itself water tight.

I'll try this first. Call me over-fastidious but I've timed the drips and if they slow up good, if they speed up, bad.

 

[DIY-JC]

Changing tack. I took a look and the leak appears to be right on the fold in the cast iron so I couldn't put a plate over it if I wanted to.
Scrapping the plate CT1 looks like it would do the job of sealing the hole on its own from the inside. Fernox LS-X always calls itself an external sealant.
Fingers crossed it will just seal itself up. I am in the North of England so hopefully the hard water will come into it's own and bung the drip.