Why is there air in the urea tank?
3 Answers
Air in the urea tank may be caused by a clogged metering pump. Introduction to the urea tank: The urea tank contains urea solution, primarily used in trucks and buses. Its function is to reduce nitrogen oxide pollution in diesel vehicle exhaust. After passing through the urea tank, the vehicle's exhaust emissions meet the China IV standard. Urea refill cycle for vehicles: Urea is typically refilled every 2,000 kilometers, with approximately 3~5 liters of urea used per 100 liters of diesel. Strictly speaking, there is no precise or uniform answer to this question. Whether a vehicle requires urea replenishment should be determined based on the dashboard display.
I've been driving trucks for seven or eight years, and it's quite common to have gas in the urea tank. Urea tends to decompose and produce ammonia gas at high temperatures, so it's normal to hear bubbling sounds in the tank during long-distance trips, especially in summer when temperatures are higher. However, excessive gas is problematic—for example, if the urea pump's seal ring is worn and leaks, or if the urea nozzle is clogged and can't vent, gas will accumulate in the tank. I recommend checking whether the urea pump's pressure is normal and inspecting the nozzle for crystallization blockages. Additionally, poor-quality urea can also lead to excessive gas production, so it's best to choose reputable brands and avoid products from small workshops.
When repairing vehicles, it's common to encounter drivers complaining about the urea tank emitting gas. I usually start by checking if the air path is clear. The urea pump needs to draw in fresh air to mix with the urea solution. If the air filter is clogged or the vent pipe is bent, the air gets trapped inside the tank. There have also been cases where the urea was overfilled, causing the expanding gas to have nowhere to escape after parking, which can push open the lid—quite dangerous. Remember to regularly inspect the vent pipe and fluid level, ensuring it doesn't exceed the maximum mark. If all else fails, replacing the urea pump's filter might help, a fix that only costs about twenty or thirty yuan.
