BMW 5 Series cool car has a lot of noise when it starts fire, which has been encountered by many car owners. The possibility of BMW 5 Series cold start sound is: the sound is very small after starting for about 1 minute, which is a normal phenomenon. It is recommended to warm up the car for 1-2 minutes first; After starting for a while, the idle noise is still very loud. If there is a loud noise from the engine, please repair it in time. BMW 5 Series cold start noise, not necessarily a fault.
Analysis on the causes of loud sparking noise of BMW 5 Series
1、如果冷启动，发动机声音偏响，一分钟后趋于安静，热启动时声音就很小，这种属于正常现象。因为停车后，发动机内的机油会自动流回油底壳。第 二 天冷启动的时候，机油会慢慢从油底壳回到汽缸盖附近。如果是热启动，发动机内的机油都已经到位，润滑和密封良好，声音自然会小。所以，冷启动声音会比较大，但是持续时间不会很长，多2分钟。
1. If the engine sounds slightly during cold start, it tends to be quiet after one minute, and the sound is very small during hot start, which is a normal phenomenon. Because after parking, the engine oil will automatically flow back to the oil pan. During cold start the next day, the oil will slowly return from the oil pan to near the cylinder head. If it is a hot start, the oil in the engine is in place, the lubrication and sealing are good, and the sound is naturally small. Therefore, the cold start sound will be relatively loud, but the duration will not be very long, 2 minutes more.
2. If the engine makes a loud noise and creaks during the cold start, check the use of the engine oil. If you use poor quality gasoline, it will also lead to the decrease of engine power, the increase of carbon deposition inside the engine and the increase of engine noise.
3. If the engine has resonance phenomenon, it will also cause the engine noise. The creaking noise should be the abnormal noise caused by the sliding of the water pump belt or engine belt after aging, or the abrasion of the water pump impeller, water pump bearing or generator bearing after lack of lubrication. It may also be caused by the friction between the engine claw and the bracket when the engine jitters greatly. Check these items one by one to find out the cause.