It would, but hard to do with a crack. Depends on where it is. You'd have to get the tank situated so that the crack was perfectly horizontal. Then you'd have to be able to set the width just right to allow for capillary action to pull the liquid solvent in. Then apply some pressure. Very hard to do with the liquid solvent on an existing tank. Much easier when first assembling.BillD said:This is just a guess, but I would think that if the crack were tight using the correct solvent cement would re fuse the material, like it would if you were assembling 2 pieces.