What Causes Abnormal Noises When Starting a Sedan?
1 Answers
The reasons for abnormal noises when starting a sedan: 1. Worn hydraulic lifters or system pressure loss. Normally, hydraulic lifters are always filled with oil at a certain pressure to ensure zero valve clearance, preventing valve noise during operation; 2. Insufficient lubrication system pressure or severely worn hydraulic lifters, where the pressure inside the lifter is inadequate to support the plunger, leading to increased valve clearance and resulting in a tapping sound from the valves during engine operation; 3. Severely worn hydraulic lifters may leak oil when the car is parked for an extended period, causing insufficient oil inside the hydraulic lifters upon the first start, resulting in a tapping sound from the valve stems.