Why does the car engine sound so loud when the weather is cold?

The reason here is generally that the temperature drops from about 30 degrees in summer to more than 10 degrees, which causes the fluidity of the engine's lubrication system to decrease, and because the rubber parts become harder at lower temperatures, Therefore, the vibration will increase when the car is cold started. As the weather gets colder, the engine lubricating oil and the gear oil in the gearbox thicken and increase in viscosity, which makes the car's idling unstable and the idling speed must be increased. This makes the car's noise become louder when idling.

As the weather gets colder, in addition to the thickening of the lubricating oil, the gap between the cylinder and the piston becomes larger, the compression leakage increases, and the combustion worsens. More fuel must be added to meet the previous requirements. load. In this way, it feels louder than before when driving a sports car. Due to the cold weather, the combustible mixture is not evenly mixed before, combustion is incomplete, and power is reduced. In order to obtain the original speed, the accelerator will be increased unconsciously. So of course the sound is louder than before. Due to the low temperature, the fitting gaps between the engine and chassis components are enlarged, causing mechanical noise. In this way, the noise of the entire vehicle is obviously louder than before. As long as it's not very difficult to start due to cold weather, and as long as it basically returns to normal after the car is warmed up, I think it should be considered normal.

Due to the drop in temperature, the three-way catalytic converter will also become colder, causing it to fail to reach the temperature required for operation. This will cause the vehicle to increase the amount of fuel injection in an instant when starting, causing the three-way catalytic converter inlet to heat up. As a result, the exhaust gas containing a large number of pollutants is eliminated, which smells very pungent. When it slows down, the smell of exhaust gas is not that strong, which is why it takes longer for the car's cold start speed to return to normal levels in winter than in summer.

Plastic parts in the engine compartment are loose. For example, the engine cover, air intake pipe, etc. can be tightened. The engine belt makes abnormal noise. Including power-assisted belts, generator belts, etc. If the belt is old or is too loose or too tight, it will produce abnormal noise. Replace or adjust the tightness. The condition of the engine oil is wrong: Engine oil is an important component of engine lubrication. When there is a problem with the engine oil, it will affect the working condition of the engine. When the viscosity of the engine oil is too high, it is easy to cause problems in engine operation, and the lubrication effect becomes poor, causing friction during engine operation, thereby producing noise.

Some people may think that after starting a vehicle in winter, you must wait until the vehicle is stable before driving, but in fact it is not necessary, because generally after the vehicle is started, the oil in the engine is already in place and lubricated, so the engine is The wear and tear is not too big. If you are not in a hurry, of course it is better to let the car wait for a while before running again.