The function of the diesel filter element is to filter out impurities and moisture in the fuel system to ensure the normal operation of the engine, reduce wear, avoid clogging, and extend the service life of the engine. 

In theory, the frequency of draining water from the diesel filter element is once a day, but it must be combined with specific conditions. If the vehicle is used more frequently, the frequency of draining water will also increase.

Diesel filter draining steps
1. Park the vehicle on a flat road, pull out the oil outlet pipe of the diesel filter element from the engine after the flame is turned off;
2. Close the cover of the diesel filter element;
3. Use a wrench to open the exhaust port of the diesel filter element, keeping the internal and external air pressure consistent;
4. Open the waterproof valve of the diesel filter element, and the water inside will flow out naturally;
5. After the water flow is over, close the exhaust port and cover of the diesel filter element, and connect the oil outlet pipe to the engine.

In addition to frequent draining of water, the diesel filter should also be replaced regularly. If it is not replaced after long-term use, the diesel filter will become clogged, which will cause some adverse effects. For example, the lack of fuel supply makes the vehicle insufficiently powered, difficult to start, and even black smoke at the exhaust port, which affects the working performance of the engine, increases fuel consumption, reduces the service life of the engine, and so on.

The life cycle of the diesel filter is generally about 5000-10000 kilometers, but it depends on the actual situation. If you feel that the power is insufficient and it is difficult to start, you can check the filter. If the filter is dirty and cannot filter the impurities and moisture of the fuel system well, it needs to be replaced.