What causes abnormal noise when starting the car?
1 Answers
Reasons for abnormal noise when starting the car: 1. Pressure: The hydraulic tappet is worn or the system is depressurized. Under normal circumstances, the hydraulic tappet is always filled with a certain pressure of engine oil to ensure zero valve clearance, and the valve will not make noise during operation. 2. Lubrication: The lubrication system pressure is insufficient, and the pressure inside the hydraulic tappet is not enough to support the plunger, which increases the valve clearance, and the engine will produce a tapping sound of the valve during operation. 3. Severe wear: The hydraulic tappet is severely worn. When the car is parked for a long time, the oil in the hydraulic tappet leaks out. When the car is started for the first time, due to insufficient oil inside the hydraulic tappet, a tapping sound of the valve stem hitting occurs.