Hi, I have an old cast iron radiator that is leaking
between the sections. The joints are cone shaped, male
and female, but the sealing takes place at the base of
the cone which has a flat area about 1/4" wide. Two
5/8" threaded rods hold the 7 sections together. I've had
them apart four times and they still seep. First I used
permatex form a gasket by itself. Then I used the same
stuff in combination with hand cut 1/32" thick gasket
material. Then I used silicone gasket maker with the
hand cut gasket material. My plumber says they can't be
repaired and it needs to be replaced, but I'm not ready
to give up yet - damn close, though. After all, it was
put together once before and didn't leak for decades. I've
heard that jb weld works, but if I use that and it still
leaks, I might not be able to get it apart again. The fellow
at the local plumbing supply store suggested using candle
wick, yarn, or twine with the permatex or silicone instead
of the 1/32" gasket material, theory being that the twine
will conform to irregularities in the sealing surface better
than a uniform thickness gasket. The fit is not precise, and
assembly without any silicone reveals gaps almost 1/16"
wide in some places. Oddly, that is not where it leaked,
though. Unless I get a better suggestion here, I'll try the
twine and silicone.