Hello, mine is Bora 20 14 automatic comfort type. It was cold in the morning, but it stopped ringing after driving for a few minutes. What is the reason?

Abnormal noise, jitter, frustration, etc. , are problems that cars often encounter, and sometimes they are big problems that need to be solved urgently. Abnormal noise includes engine abnormal noise, cab abnormal noise, chassis abnormal noise, etc. Among them, the abnormal sound of the cab and chassis is not necessarily a fault, but may be caused by the loose fixing of the interior trim panel or chassis parts, but the abnormal sound of the engine is mostly caused by the fault.

No matter what causes the abnormal noise, it will make people feel uncomfortable when the car is driving. Some abnormal noises are very strange. They will appear when the car is cold and become smaller or disappear when the car is hot. This problem can easily be attributed to the sound produced by insufficient engine oil activity and excessive friction when the car is cold, and can also be explained as the sound produced by thermal expansion and cold contraction.

Sometimes it makes sense, but sometimes it's obviously not that simple. For example, these four kinds of faults may be the "culprits" that cause abnormal noise of cold cars.

First, the generator belt

When the car is cold, including cold start, the sound of the belt may play an important role in the noise of the car. If the belt is loose and slips seriously, it will grind louder, which is one reason; Another reason may be that there are foreign objects in the belt, such as sand, pebbles, etc., and abnormal noise may also occur. Why is the abnormal noise of the belt relatively large in cold state? The reason is that the belt is hard at low temperature, which will make a squeaking sound, while at high temperature, it has better elasticity, which will reduce the rubbing sound.

Too loose belt is related to the aging and hardening of belt or the failure of tensioner, which still needs attention.

Second, the fuel pump failure

When the car is cold, it squeaks like an electric current, and the noise caused by the vibration of the belt and tubing can be eliminated. We can consider whether it is caused by fuel pump failure. Failure of fuel pump can easily lead to low oil pressure and poor atomization of fuel nozzle, resulting in unbalanced mixing ratio and insufficient combustion.

The failure of fuel pump is mostly due to the addition of fuel with poor oil quality, which leads to the blockage of filter screen or direct burning out. General fuel pump failure needs to be replaced directly.

Third, the oil pump bearing failure

Unlike the fuel pump, the oil pump is directly driven by the crankshaft. Failure of oil pump will cause low oil pressure in lubrication system, which will cause problems in lubricating oil circulation and increase engine noise, which is mostly caused by dry friction when oil lubrication is insufficient.

The bearing wear of rotor oil pump will cause looseness. When the inner and outer rotors scrape, abnormal noise will appear when the car is cold, and it will be much lighter when it is hot. As for why this happens, the main reason is that the protective oil film is poor when the car is cold, but it will be much better at high temperature. In this case, the oil pump needs to be replaced directly.

Four, camshaft tensioner failure

The fault of camshaft tensioner is mainly reflected in the abnormal sound and sometimes harsh at the timing chain when the car is cold. The camshaft is connected with a tensioner, which provides tension through oil pressure. If the tensioner fails, it is easy to cause the timing chain to jump and cause the ignition timing error. According to the severity of vehicle trip, there are a series of symptoms such as unstable idle speed, jitter and power drop.