all talk and no cider

All talk and no action. Full of strong words, promises, or intentions, but failing either to act on those words or to achieve results. He keeps threatening to quit if he doesn't get a raise, but I think he's all talk and no cider, considering how long he's been here. She may brag about donating money to the school, but I know she's all talk and no cider. John's all talk and no cider, so I doubt he'll really help you move those boxes, like he said he would.