What is the difference between cold start and hot start engine?

Category:Automobile engine repair - Date:2017-04-01
As a car owner, cold start should be often heard of a word, and even often speak, for example, in winter some owners often ask "how is my car cold start shivering?" It is difficult to start the cold car of my car. It often needs a few fires to start. What is the problem? Similarly, the same hot start word is also commonly used in cars, but do you really know what they mean? Do you know the difference between them? Here will be a popular science.

What is the cold start of the engine

cold start is started under the condition of low water temperature of the engine. It usually takes a long time to start the car (for example, after night parking). After the engine is flameout for a period of time, the engine has cooled, its temperature is much lower than the normal working temperature, and the oil is basically reflux, then start again, it is cold start.

In general, we can use the ambient temperature to measure the temperature, that is, the temperature of the engine is cooled down to below 40 degrees C, which is usually about 2 hours. This time the restart is cold start.


Engine Cold start What do you need to pay attention to?

80% of automotive engine wear occurs during cold start. Therefore, when starting the engine should be preheated cold, or hot.
before engine preheating, the clearances of the parts are larger and the lubricating oil is sunk to the bottom of the oil. After driving, it is necessary to warm up at one end and expand before the machine is preheated, so that the required clearance can be gradually achieved. The oil pump works at the same time to transport the oil to the part that needs lubrication. The oil should be circulated to the main parts for more than ten seconds after the engine is started. At this time, the wear of the machine parts will be increased if the rush of oil is added and the speed of the engine is rapidly heated.
Therefore, when the cold car starts, it should be "slow to shake and slow down", that is to wait patiently in the state of idle speed. It is best to wait until the pointer of the water temperature meter starts to rise and then start the driving.

In particular, in winter, this preheating time is longer, the car with a hand door can open the hand, and then with the rising of the engine temperature, the door is gradually returned to the hand, until the water temperature is normal and then start the driving. For the EFI engine or automatic air door carburetor engine, the idling speed is very high when the cold car starts in winter, usually about 1200/. At this time, the oil flow is poor, and the lubrication effect is not good. It is not suitable for high-speed walking or heavy load. When the idle speed drops to about 850/, the temperature inside the cylinder has increased, the oil has been fully flowing, the engine has been preliminarily preheated, and it can start to walk slowly.


What is the hot start of the engine

when the car stops after normal driving, it will start at once, which is called hot start when the engine is still in hot state. Simply say that hot start is, the engine is not a moment after the fire, the engine temperature is still near the normal working temperature, no drop, the engine friction surface oil does not return, oil film is still, then start, is hot start.


The difference between cold start and hot start
cold start is to start the engine when the engine's water temperature is low.

hot start is to start the engine at high temperature of the engine, and the difference is just the temperature of cooling water.

1. The cold start is more damaging to the car, and the wear of over 80% of the engine is caused by the cold start stage.

2. Cold start is more difficult to start the car and start longer than the hot start. There are 3 reasons:

when a and cold start, the internal temperature of the engine is too low, and the mixture is not easy to vaporize and burn.

B, cold start, the engine oil temperature is not enough, even if the appropriate viscosity of the oil, cold starting moment is equivalent to the viscosity is too large, need time to improve the temperature of oil, thus accelerating the lubrication of the engine parts;

When C and cold start, the gap between the parts of the engine is large. It needs to be preheated by the time. After the preheating expansion, the clearance can be reached gradually, because if the gap is too large, the oil oil film can not be covered with lubrication.

In this case, we have to say that the original heat car in winter, a lot of people say that modern cars do not need hot cars, but people think: the start of the car in the winter, a cold iron pimple, the total time to improve the internal temperature to make the internal parts to reach the appropriate value, the total time to let the cold machine The oil flow through the engine, even if the time short also need ten seconds, so wait a half minutes or good.



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