Drain the water, then solder
Shut off the water at the main
valve in your home and open up
nearby faucets to completely drain
the pipe with the leaky elbow. Dry
the outside of the elbow and sand
(120-grit paper or cloth) around
the leaking joint to remove all surface
corrosion. Apply soldering
flux around the whole joint and
apply heat with a torch until the
old solder melts. Add new solder
until a shiny ring of solder shows
all around the joint. Let the pipe
cool for five minutes, then turn
the water back on and cross your
fingers that you stopped the leak.
If the leak continues . . .
Turn off the water again, open
faucets to drain the line and cut out the entire elbow. Then solder
in new fittings.
A last ditch effort . . .
Sometimes you can't solder in the
new fittings because there's a continuous
slow trickle of water. If
you don't want to wait for the
water to completely drain, try this
trick. Replace the elbow with a tee
with a threaded fitting soldered
on one end. This open end allows
any moisture to escape as steam
so you can heat the joint enough
to melt the solder. When the pipe
has cooled, screw in a threaded
plug. Be sure to use Teflon tape or
pipe compound on the threads.