On Apr 21, 4:25*pm, "Roger Cain"
wrote:

In the dark ages the fix was to take 2 steel washers, 2 rubber washers,
drill through the crack and bolt washers either side to make the seal.

Good fix for rust pinholes, but it won't work near a non-flat seam.

I'd dry it out well (maybe on the stove a bit) then paint the inside
with some bitumen black paint (cheap from Screwfix, dead handy). Two
coats should seal any crimped joints that have sprung open.