Ask The Editors: Gas Cap Won’t Turn
There’s a few reasons a gas cap can become almost impossible to remove. The most common of these is the rapid change of pressure inside of the tank that pushes and pulls on the plastic, often swelling the rubber gasket of the cap itself.
Though, in this case we have to wonder if fuel has ever been poured into the machine – which would likely be a locked cap due not to swollen plastic but the vacuum-like seal around the gas cap that can form when a tank is (or is run) empty.
Either way, getting the cap off when hand torque alone won’t do it often requires the use of a repeated tap – we usually use a rubber mallet and catch one of the hand hold tabs. Give it repeated, steady taps until that initial seal breaks enough to allow the cap to turn, then simply unscrew it the rest of the way by hand.
With repeated removals, it should become easier over time – taking a bit of motor oil on your finger and smearing it around the underside of the cap and on the threads of the tank itself where the cap screws onto should help if it continues to remain difficult to remove.
