What is the reason for the clattering sound of starting the car s engine and cold car?

The reasons for the clattering of the cold car engine are: 1. Automobile engine.

Oil causes: The engine's lubricating oil will flow back into the engine oil pan, and when the car is started, it cannot be lubricated in the first place, so there will be a rattling phenomenon. 2. The cleaning valve causes: When the car starts, the carbon canister solenoid valve.

Gasoline vapor can be adsorbed, and through the vacuum of the intake manifold, it enters the cylinder, and in the process, there may be a clattering sound.

The cold start engine clattering sound is due to the car parked for a day, the lubricating oil of the engine basically flows back to the oil pan, when the engine starts cold, the oil pump can not establish the oil pressure in the first time, and the oil film is formed between the components, especially the valve inside the cylinder head (upper part), which can not be lubricated during the cold start, whether it is a hydraulic tappet or a mechanical rocker arm, there will be a certain valve clearance, resulting in a clattering sound.

Start the car engine, in the state of cold car, the engine makes a clattering sound, which is the sound of the valve, after the temperature comes up, the valve clearance will be reduced, and the sound will not be so loud.

There is a clattering sound in the engine, which may be caused by the following reasons:

1. Abnormal noise of engine belts, such as generator belts, air conditioning belts, steering pump belts, etc., may be too loose or too tight, or it may be that the belt is aging, adjust the tightness of the belt, apply butter to the belt, or replace the belt.

2. The engine lacks cylinders, a cylinder does not work, the engine will be unbalanced and produce abnormal noise, and it is also accompanied by the violent shaking of the engine, insufficient power and other faults, which may be the fault of the ignition module, spark plug and fuel injector, and the corresponding accessories can be replaced.

3. Engine "tempering" failure. When the car slows down and collects the oil, there is a "poof" sound, which may be the engine "tempering" failure, which is usually called the engine "fire", too much carbon deposition on the valve or the wrong timing of the valve will produce abnormal noise, cleaning the carbon deposit on the valve or adjusting the timing of the valve.

1. Automobile engine oil causes: The lubricating oil of the engine will flow back to the engine oil pan, and when the car is started, it cannot be lubricated at the first time, so there will be a clicking phenomenon. 2. Cleaning valve causes:

When the car starts, the canister solenoid valve can adsorb gasoline vapor, and through the vacuum of the intake manifold, it enters the cylinder, and in the process, there may be a clicking phenomenon.

When the cold car starts, the engine clatters, and there are several possibilities:

1. When the cold car starts, if it can start normally, after the hot car, the abnormal sound of the clatter disappears, which is a normal phenomenon. Generally, the oil pump has not fully established the oil pressure during the cold start, and the parts are not lubricated.

2. When the cold car starts, if it can start normally, after the hot car, the abnormal sound of the clatter still exists, indicating that there is a problem. There are many reasons involved in this aspect, such as the sound of the main bearing of the crankshaft, the sound of the connecting rod bearing, the sound of the crankshaft breakage, the sound of the piston ring, etc., which will cause the abnormal sound of the clatter, and generally only need to replace the problematic parts to solve the problem.

It is more common that the machine foot pad (also called machine foot glue, chicken foot pad, etc.) is aging or loose, and when it is serious, there will be a clattering noise, which only needs to be replaced with a new machine foot pad.

3. When the cold car starts, there is a clattering sound, and there is no fire, and the battery fault light and engine fault light on the dashboard are lit, which can basically be determined to be a battery problem. The battery is running out of power or has an expiration date.

The engine cover can be opened to look at the viewing holes of the battery. Green is good, black means something is wrong. In general, there will be instructions on the surface of the battery. If it is determined that there is a problem with the battery, it is recommended to replace it.

<> "When the car is parked for too long, when it is restarted, there will be a wild rattling sound, and then the sound will slowly disappear. So what is the reason for the clattering of the engine when the car starts cold?

When the cold car starts, the engine clatters for two reasons

If the engine clatters quietly when the car starts cold, and then it doesn't sound when the car is warmed up, it is normal. Because the oil is more viscous at this time, the fluidity is worse than the normal state, and there may be some clattering sounds in a short time, but after the car is started, the parts will return to normal under operation, and the sound will naturally disappear.

If the engine clatters loudly when the cold car starts, it may be caused by the failure of the engine belt or valve. However, if you want to determine the problem specifically, you also need to send the car to a 4S shop and other auto repair shops for detailed maintenance.

Pacific Automobile Network] cold start engine clatter is due to the car parked for a day, the engine lubricating oil basically all flow back to the oil pan, in the engine cold start, the oil pump can not establish the oil pressure in the first time, the formation of oil film between the components, especially the valve inside the cylinder head (upper), can not be lubricated during the cold start, whether it is a hydraulic tappet or a mechanical rocker arm will have a certain valve clearance, resulting in a clattering sound.

When the engine runs for a period of time, the oil pressure builds up the oil film, the oil temperature rises, and the sound of "da-da" disappears after the engine works normally (note, if the engine has been clattering when the car is hot, go to the repair shop for testing as soon as possible). In addition to the cause of the oil, there is another element of the engine that will also make a clattering sound - the solenoid valve (cleaning valve) of the carbon canister, which is used when the engine starts, the solenoid valve between the canister and the intake manifold is opened, and the gasoline vapor adsorbed by the canister is brought into the cylinder by air to participate in combustion under the vacuum of the intake manifold. This not only reduces emissions, but also reduces fuel consumption, which also makes a clattering sound during operation.

Addendum: Oil quality issues can sometimes make the engine rattle).

Therefore, the clatter sound of the car cold start is not a fault, if this abnormal sound occurs when the car is hot, you need to pay attention to it, and this phenomenon will also occur when the engine of some luxury cars is cold started. (Photo by Photo: Pacific Automobile Network Zhang Feng disturbed the rock snow)

Automobile squeak includes engine squeak, clutch squeeze, transmission squeak, final drive squeak, suspension system squeak, brake squeak, steering squeak and body squeak.

On the issue of abnormal noise of automobiles, it is difficult for ordinary car owners to distinguish which ones are abnormal noises and which ones are reasonable abnormal noises. Only nearly 20% of the vehicles that went to the repair shop to detect abnormal noises really had problems. Models equipped with turbocharged engines are different; Models with engine guards may also make noises due to friction; After some car owners come into contact with different cars, it is likely that due to their lack of understanding of mechanical knowledge, they mistake reasonable abnormal noise as a vehicle failure.

Therefore, learn to distinguish the abnormal noise of the car and avoid wasting time and energy.

Second, the identification method of car noise:

In practice, due to the limitations of working conditions, it is difficult to measure the sound of the car with special instruments, and the sound of the car can only be described and compared with the judgment of the sound in daily life. For example, the "rattle" sound caused by the dry friction of the bearing, and the "click" sound similar to the small hammer hitting the cement floor caused by the excessive valve clearance.

1. Correctly distinguish between normal and abnormal sounds.

The vibration of each mechanism in the work of the car will emit a variety of sounds, but the sound does not mean that the car is faulty, in order to avoid unnecessary disassembly, we must first distinguish between normal sound and abnormal noise. The normal vibration sound of each system component (such as the noise on the surface of the engine), the impact sound of the gear when shifting, the air intake sound and exhaust sound of using gas as the working source, and the gear meshing noise are all normal sounds. Abnormal noise (abnormal noise) can be divided into slight noise, general delay sound and malignant sound according to the impact on the performance of the car.

Slight noise, such as the flashover sound of high-voltage electric leakage, the slight loose sound of rolling bearings, etc., the general volume is small, the degree of wear of the parts is not large, and there is no significant change for a long time, and this kind of fault can still maintain the normal operation of the car without repair.

3. When diagnosing the abnormal noise of the car, attention should be paid to creating good auscultation conditions and trying to eliminate the interference of other noises, so as not to affect the accuracy of judgment.

It is best to consciously amplify or reduce the sound, that is, use a screw or other metal rod as a stestological instrument to contact the sound part to amplify the sound, or use a single cylinder fire cut-off to reduce the sound to meet the diagnostic needs. The auscultation site should be kept quiet to minimize human interference.

The reason for the clattering of the engine when the car starts cold is that the oil pump cannot establish the oil pressure in the first place, and the parts are not lubricated.

The cold start engine clattering sound is due to the car parked for a day, the lubricating oil of the engine basically flows back to the oil pan, when the engine starts cold, the oil pump can not establish the oil pressure in the first time, and the oil film is formed between the components, especially the valve inside the cylinder head (upper part), which can not be lubricated during the cold start, whether it is a hydraulic tappet or a mechanical rocker arm, there will be a certain valve clearance, resulting in a clattering sound.

Hazards of cold starting:

Cold start refers to the direct start of the car without preheating, mostly refers to the cold areas in the north, driving without preheating the damage to the car is like running a long distance without warm-up exercises, it is easy to be injured.

For automobiles, the engine oil has not been lubricated all parts of the engine, especially the crankshaft and crankshaft pads, which are easy to strain. Pistons and piston rings are prone to carbon deposits, which can cause oil deterioration. The driving capacity of the car will also decrease, which will also shorten the life of the engine.

It is recommended to preheat in advance, run the engine without load for 5 to 10 minutes [gasoline engine] diesel engine needs to use 15 to 20 minutes, and the water temperature is kept between 60 and 80 degrees, which is the best temperature for the engine to work.

The owner of the car has an abnormal noise when the car starts cold, and it will be fine after a while, and it is normal for such a situation to occur.

Because the vehicle is in a cold state when it starts, many parts and components do not reach the normal working state, and there will be abnormal noises, and when the parts and components reach the normal working state, these abnormal noises will disappear.

When the vehicle starts cold, the hot car and the unhot car will have an impact on the driving state, and if it is so cold in winter, the impact will be more obvious, so the hot car is still useful. In the summer, you can warm up the car for 20 seconds, and in the winter you can do it for 40 seconds, and you can drive after the engine speed has stabilized and the water temperature has risen.

Inspect the vehicle

It is possible that all the lubricating oil of the engine has flowed back into the oil pan, which is very easy to happen if the vehicle is parked for a day and does not drive. When the engine is starting, the oil pump cannot immediately establish oil pressure without lubricating oil, and the components cannot form an oil film. In particular, the valve of the cylinder head, if the cold start needs to be lubricated, if there is no lubrication, it will cause the valve clearance of the mechanical rocker arm, resulting in a clattering sound.

If the pressure of the lubrication system is insufficient, or the hydraulic tappet is seriously worn, the pressure in the hydraulic tappet is not enough to support the plunger, the valve clearance will increase, and the engine will produce a "click" valve knocking sound when working.

When the car is parked for too long, when it is restarted, there will be a clattering sound, and then the sound will slowly disappear.

In fact, this is a normal phenomenon, cold weather will lead to poor fluidity of oil, can not flow as fast as normal temperature, so when the car just starts, the engine can not be particularly stable, it will make a clattering sound. When the temperature rises slowly, the sound will slowly weaken and disappear.

When the car starts cold, the engine may appear idling instability, this phenomenon is high and low, the reason for this situation is that the car does not open the valve when starting, resulting in instability when the engine starts. In addition, when the engine starts cold, the idle control valve is faulty, and the idle speed of the engine becomes slower, which will be unstable. The rattling sound of the cold car is also related to the quality of the oil, and when the quality of the oil is not good, it will make a rattling sound.

Many car owners don't understand why there is a clattering sound, the clatter of a cold car is not a fault problem, if it is a hot car starting to make a sound, you need to pay attention.

One. Cold knock cylinder piston knock cylinder rattle refers to the piston swinging or channeling in the cylinder when moving up and down, and its head or skirt collides with the cylinder wall and cylinder head to produce abnormal sound, which can be divided into cold knock cylinder, hot knock cylinder and hot and cold knock cylinder. Fault symptom 1

There is a knocking sound at low temperatures, and the sound weakens or disappears when the engine temperature is normal. 2.At idle or low speed, it makes a clear and rhythmic "click" sound.