With the launch of the new "National 6" vehicle models, engines are becoming increasingly "refined," which requires truck owners to enhance their daily maintenance to extend engine life and reduce operational malfunctions. Below, our editor highlights special attention points regarding the use and maintenance of urea for "National 6" diesel vehicles.

Utilize GB29518 standard urea solution to ensure the internal cleanliness of the urea tank.

Poor quality urea can cause blockages and even damage to urea pumps and nozzles, leading to crystallization and blockages in the SCR box, resulting in excessive emissions. Additionally, when the urea level drops below 10%, the NCD indicator light will remain on as a reminder, necessitating immediate urea refueling. Otherwise, the engine will be immediately limited when the level falls below 5%.

Maintenance of 2 urea tanks

Urea tank sensors should be cleaned at least once a year; under low temperatures, urea can freeze and expand by about 8%. When refilling urea solution, do not overfill; leave some space at the top of the tank to accommodate expansion, preventing the tank from cracking or the liquid level temperature sensor from being damaged due to urea freezing and expanding. For Weichai's 35L urea tank (total volume of about 40L), the refilling amount should not exceed 36L, and for the 50L urea tank (total volume of about 60L), the refilling amount should not exceed 52L. During operation, if the urea level is too low (below 10%), the system will report a low urea level fault.

Important Filling Instructions for 3 Urea Liquid

Regularly check the urea solution level in the urea tank and promptly replenish as needed. The dosage of urea solution for vehicles is 3%-8% of diesel usage. Estimate the amount of urea solution based on the mileage, and carry sufficient bulk urea as necessary.

When refueling with urea solution for vehicles, it is recommended to use a refueling tube to prevent debris from mixing in.

After adding the urea solution, make sure to tighten the lid of the urea tank to prevent airborne contaminants from entering, which could cause the urea to deteriorate or crystallize.

Important Storage and Transportation Precautions for Urea Liquid

Urea solution for vehicles should be stored and transported away from direct sunlight and high temperatures, with a storage and transportation temperature range of -5℃ to 25℃. Urea crystals may precipitate at -11℃; to dissolve the crystals during refueling, use warm water below 30℃ to dissolve them, which will not affect the normal use of the urea solution for vehicles.

5 Urea Liquid Crystallization Treatment

Urea solution crystallization is a common occurrence, but it is not recommended to clean it with detergents, as commercial detergents can damage the catalyst, a crucial component of the SCR system. A better approach is to rinse with hot water, which does not harm the SCR system and effectively removes the crystallization.

Do you need to add antifreeze urea solution?

The vehicle-mounted SCR system, equipped with an auxiliary heating system, is controlled by the urea injection control unit (DCU) and ensures the SCR system operates normally at -30℃ temperatures, eliminating concerns about urea solution crystallization in winter.