Apply an Epoxy Sealer on a Leaking Gas Tank

| 10/21/2013 11:41:00 AM

Clean and seal a leaking gas tank

I have never been a fan of using tank sealers, but sometimes you don't have a choice. Recently, the tank on my 1964 Triumph T100SC started seeping at a spot weld under the right side strut securing the tank kneepad. I didn't want to repaint the tank, so the easiest fix was to epoxy coat the tank and seal the leak from the inside. 

Fortunately, this is a project within most people's grasp. It's not a difficult task, but careful preparation is key, especially if you have an expensive paint job to protect. Materials needed include bolts or rubber plugs to seal the fuel tap threads, a rubber bung to seal the filler neck, plastic wrap and newspapers to protect the paint, rubber gloves to protect your hands, a container for mixing the epoxy, a mixing stick and the sealer, of course. Finally, a clean workspace with enough room to move the tank around so the coating is evenly applied is important.

When choosing a sealer, make sure it will stand up to the ethanol in modern gas. A Novolac epoxy sealer such as Caswell sealer will do that. Prepare the tank by removing anything you can unscrew from it, such as badges, filler cap, fuel taps and kneepads. If you use bolts to seal the tap holes, wrap them with Teflon tape. If you use rubber plugs, push them in firmly. You don't want any epoxy leaking out.

11/7/2013 7:13:40 AM

That's a problem I haven't had to contend with yet, all the tanks I've sealed have been old enough to only have the cap vent, no emissions controls. I think you've got the right idea for dealing with newer tanks with evaporative emissions controls.

10/24/2013 9:23:03 AM

I'd like to know the technique for preserving the tank ventilation system. I have a used '86 BMW-R80 with the California emission controls that apparently has had the epoxy sealing process applied to it. The tank vent line is plugged, so I had to drill a hole in the cap. I would suggest taping over or plugging the vent tube at both ends (on the center outside of the tank and the opening inside the filler neck) prior to applying the epoxy.

10/24/2013 7:30:11 AM

I coated several tanks back in the day but always because of rust never a pin hole leak. I would put a hand full of bolts/nuts inside with water and shake the tank to break rust loose, before useing a rustremover product. Then I would use a magnet to remove the bolts/nuts. I never plastic wrapped a tank but all the tanks I did were going to get repainted so it wasn't as important.