from the JB weld website...........
Q: Is J-B Weld resistant to water and/or gasoline?
A: When fully cured, J-B Weld is completely resistant to water, gasoline, and about every other petroleum product or automotive chemical. For wet-surface or submerged water or gasoline repairs, see our J-B Stik or Waterweld product information.
http://jbweld.net/faq.php/