1. The brake is too soft: when the brake is stepped on, if the texture of the du brake is obviously softer, and the stability of the brake is decreased, it may be the master cylinder and the sub-cylinder. Poor piston seal, or a rupture somewhere in the brake pipe, causing oil leakage. At this time, you need to observe whether there are traces of brake fluid.
2. Sudden failure of the brake: When the car is braking, if you feel that it suddenly fails for a moment, you need to observe whether the brake fluid is losing money, and then check the master cylinder, the sub-cylinder and the oil pipe for signs of braking. If there is, it means that the brake master cylinder or the sub-cylinder has leaked very seriously, and it must be repaired in time. It is necessary to know that the consequences of brake failure are very dangerous.
3. The brake pedal does not return or returns slowly: If the pedal neither rises nor resists after stepping on the brake pedal, it is the phenomenon of the brake not returning. At this time, you need to check whether the parts of the master cylinder and the sub-cylinder are damaged. Secondly, this phenomenon may be caused by lack of brake fluid or oil leakage.