The Panhead & Flathead Site

Author: skip

Hey guys...let me bounce one off you...old tanks, 48...new paint...new caps last September...leaking/seeping down neck from under caps...new seals purchased last september put on...still leaking...took razor blade to paint under cap...still leaking...should I buy new caps or new seals again? Where to buy good caps?...or what else could it be??? should both be vented?? left one is non vented now...Thanks Skip

Post by VPHD

If the tanks are really 48, both caps should be vented. Aftermarket tanks that use a gas cock in the left tank use a non vented cap on the left tank. The left tank usually will go into a vacuum with a non vented cap which goofs up the gas flow pretty well.
VPH-D

Post by dremelts

If the cap turns all the way to the stop without much resistance then maybe you need a thicker seal. I found some flat rubber at the hardware store (about 6" square) that came in a couple of different thicknesses and used some of that to make my own gas cap seals.