Why does the water temperature drop when the car starts, and the water temperature is normal when it doesn't go?

First of all, the thermostat of the engine cooling system is broken-it needs to be repaired.

Second, if the temperature in your environment is too low, then you can only put a mask on the car-this possibility is relatively small.

Extended data:

1803, the French engineer Trevico (177 1- 1833) adopted a new type of high-pressure steam engine, which can take 8 people, with an average speed of 13km. Since then, cars driven by steam engines have been applied in practice.

1838, the British inventor Hennert invented the world's first internal combustion engine ignition device, which was called "a revolution in the history of world automobile development" by the world.

1860, Lionel, a French electrical engineer, made the first gas engine that ignited gas with electric spark. 1862, French electrical engineer Lionel invented the two-stroke internal combustion engine. Others began to study the four-stroke engine.

1885, this is the moment when the real modern car was born. This year, German engineer karl benz built a tricycle with a 0.85 horsepower gasoline engine in Mannheim. This car with internal combustion engine is considered to be the real first car in the world, because it is the first car powered by gasoline, not a steam engine.

References:

Baidu encyclopedia-automobile