What is the difference between filling up the car tank until the nozzle clicks and filling it completely?
2 Answers
The differences between filling up the car tank until the nozzle clicks and filling it completely lie in the remaining space, the level of burden, and the process. The details are as follows: Remaining space is different: Filling the car tank completely means there is no remaining space in the fuel tank, while filling until the nozzle clicks indicates that there is still some space left in the tank, meaning it is not completely full. Level of burden is different: Clicking the nozzle actually protects the car's safety performance to some extent and does not affect the car. However, filling the tank completely is different. When the tank is full, it can easily lead to the vent hole being blocked. If exposed to an open flame, the car could potentially catch fire, indicating that filling the tank completely imposes a greater burden. The fueling process is different: Filling the car tank completely is a single, complete process, whereas filling until the nozzle clicks is not a complete process and can be divided into several stages. For example, the first click, the second click, and the third click. However, it is generally not recommended to proceed to the third click, as this could compromise the car's safety. How the fuel nozzle clicks: Simply put, it is achieved through a self-sealing mechanism. When the fuel level in the tank is low, the nozzle's air vent is not blocked, and fuel flows normally. When the tank is full, the nozzle's air vent gets blocked, creating negative pressure inside the nozzle. This negative pressure moves components like the ball and switch, causing the nozzle's support plate to disengage, thereby closing the valve and sealing the nozzle automatically.
As a commuter who drives to work every day, I always stop refueling when the pump automatically shuts off, as it's the most hassle-free and safe method. The fuel tank is designed with a safety margin - when it's nearly full, the pressure increases and the pump automatically stops to prevent overfilling. If you insist on topping it off and squeeze in extra fuel, the gasoline may expand and overflow on hot days, not only dirtying the car body and ground but also potentially causing leakage risks. This could damage the vehicle's evaporative control system, leading to expensive repairs. I've seen a friend's car where the charcoal canister was damaged from overfilling, resulting in a strong gasoline smell inside the car. Safety-wise, this poses driving hazards. For daily driving, filling until the pump stops is sufficient - there's no need to pursue an absolutely full tank.
