What causes the loud engine starting sound in Haval F7?
2 Answers
Haval F7's loud engine starting sound may be caused by aging or loosening of engine mounts, improper use of engine oil, or cold start conditions. Aging or loosening of engine mounts: Engine mounts are rubber blocks placed between the engine and the frame. Their function is to reduce vibration and provide cushioning during engine operation, as well as to secure the engine in place. Once these engine mounts age or become loose, the engine will vibrate, and the faster the speed, the louder the vibration noise will be. Improper use of engine oil: On one hand, if the viscosity of the engine oil does not match the engine's requirements, it can easily lead to carbon buildup, causing the engine noise to increase. On the other hand, if the oil viscosity is too low, it will result in insufficient lubrication, leading to abnormal noises from engine component wear. If the oil viscosity is too high, it will increase the engine load, also causing noise. Cold start: During a cold start, the engine's lubrication is relatively poor, the oil flow is weak, and the oil is more viscous, resulting in abnormal noises from mechanical wear. Additionally, during a cold start, the coolant temperature is low, the air-fuel mixture is rich, and incomplete combustion can cause the engine to vibrate and produce noise.
My Haval F7 also experienced unusually loud engine noise during cold starts. It was particularly noticeable in cold weather, especially when temperatures dropped below zero—the startup sounded like a tractor. Later, I consulted a professional technician who explained that this happens because engine oil has poor fluidity at low temperatures, increasing internal friction, and the ECU automatically raises the idle speed to warm up the engine quickly. Additionally, after driving the car for over two years, the noise became louder, and an inspection revealed that the alternator belt had aged and slightly loosened, causing a sharp screeching noise during startup. Another time during maintenance, I found the air filter severely clogged, which also made the engine sound rougher due to restricted airflow. Now, I switch to 0W-30 oil with better low-temperature fluidity before winter and regularly clean the throttle body, which has significantly improved the situation.
