That is, first put off the gasoline in the tank, unload the tank from the frame, flush the inside and outside of the tank with water, then turn off the switch of the tank and fill it with clear water. And tighten the box cover. Then put the oil tank filled with clear water into the freezing pool (there are such pools in cold storage, cold storage factories, places where popsicles and ice cakes are made) for freezing, and pay attention to make the sunken place slightly exposed to the freezing liquid level. The freezing time can be long or short, and it can be restored in two or three hours. After the oil tank is restored to its original state, take it out of the freezing pool and rinse it with water until all the ice in the oil tank is dissolved. Finally, drain the water in the water tank. If paint falls off from the sunken recovery part, paint it according to the primary color of the oil tank. After the paint is dried, it can be loaded for use.
Second, when the sag area of oil tank is small, it can be repaired by stretching method.
That is, first, let off the gasoline in the fuel tank, then unload the fuel tank from the frame, then find an iron bar with proper thickness, weld one end of the iron bar in the depression of the fuel tank with tin, and then clamp the other end of the iron bar in a vise. Hold the oil tank with both hands and pull it outward, and repeat it several times, and the depression can be restored to its original state. Then iron the iron bar with a soldering iron, clean up the sunken recycling part, and finally paint the sunken recycling part according to the color of the oil tank. After the paint is dried, it can be loaded for use.