Depending on how big the hole or patch to be put in , You can drain it and seal it with Seals - all then epoxy or JB weld over, Or you can remove tank and have a steel patch welded in. My Corona has a nice big drain plug in the bottom so draining the tank of a gallon or 2 of gas was quite easy,. I did the Seals- all method, but will take the tank out when time permits. Either way clean dry metal is a must. I don't like internal sealers.. a matter of taste.