What is the reason for the noise when the car starts and stops?

First, this is because the small water tank of the cooling system is installed at a higher position, and some air in the cooling system is not completely removed, which has nothing to do with antifreeze. The solution is to make the throttle high before parking, low after parking, and let the electronic fan work several times. Open the cover of the water tank to exhaust, and be careful that the safe water temperature is not too high to avoid scalding.

Second, the reasons for the cold start of the car:

1. 10W or 5W high viscosity engine oil is suitable for winter;

2. Too much carbon is deposited in the intake system and intake valve roots, which leads to too thin mixture concentration during cold start;

3. The throttle valve is seriously dirty and the air intake is insufficient;

4. The speed of the starter can't meet the requirements;

5. The contact resistance of the battery connecting wire is too large; The battery power is insufficient;

6. The viscosity of transmission lubricating oil is too thick, resulting in too great engine running resistance;

7. Insufficient compression pressure of engine cylinder;

8. High-voltage ignition system-the performance of spark plug is poor, and it can't produce an ideal spark enough to break through the mixture;

9. The spark plug is unreasonable; Engine coolant temperature sensor fault.