Some GENTLE pressure on the tank seam stopped the tiny leak there. As long as the cap ONLY holds ~13psi, this radiator should last many more years.
If I had gotten the impression that the leaks couldn't be sealed, I'd have returned the radiator to the JY for exchange, or credit until they got a better one.
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For more info,
read this article that fully explains the cooling system, and
this one that explains how to rebuild a plastic-tank radiator at home.
UPDATE: 6/5/15 the Left tank blew out farther down on the side, and I replaced it with a new one from 1800RADIATOR. I may open this old one up and fiddle with it.
