What Causes the Tapping Sound When Starting the Car?
3 Answers
When the car makes a tapping sound during startup, it indicates that the hydraulic lifter is worn or the system is losing pressure. If the lubrication system has insufficient pressure or the hydraulic lifter is severely worn, the pressure inside the hydraulic lifter is insufficient to support the plunger, leading to increased valve clearance. As a result, the engine produces a tapping sound from the valves during operation. More detailed information is as follows: 1. Most engines use hydraulic lifters: The vast majority of modern car engines employ hydraulic lifters, which are components of the engine's valve train and are typically installed on the cylinder head. Their function is to open and close the valves under the drive of the camshaft while automatically adjusting the valve clearance during operation to ensure zero clearance. This helps reduce impact, lower noise, and extend the lifespan of components. 2. Reasons for the tapping sound: Under normal conditions, the hydraulic lifter is always filled with oil at a certain pressure to maintain zero valve clearance, preventing any noise from the valves during operation. However, if the lubrication system has insufficient pressure or the hydraulic lifter is severely worn, the pressure inside the lifter cannot support the plunger, causing increased valve clearance. This results in a "tapping" sound from the valves when the engine is running. Particularly in cases of severe lifter wear, when the car is parked for an extended period, the oil inside the hydraulic lifter may leak out, leading to a distinct tapping sound from the valve stems.
A clicking sound when starting the car usually indicates a weak or aging battery. When the battery doesn't have enough power, the starter motor struggles, making an effort but failing to turn, causing the relay switch to rapidly engage and produce that sound. This issue is more noticeable in cold weather because low temperatures reduce battery efficiency. It could also be due to corroded or loose wire connections, leading to unstable current transmission; or even worn gears or contacts inside the starter, requiring repair or replacement. If you hear this sound, avoid repeatedly attempting to start the car to prevent draining the remaining power or damaging the motor system. It's recommended to immediately use a multimeter to check the battery voltage—normal readings should be above 12.5 volts. If it's lower, jump-start the car and drive to a professional shop for inspection. I regularly check my car and recommend periodic maintenance of the battery and starting components to avoid trouble.
My car once made a clicking noise during startup, which happened the winter before last. I thought it was a minor issue and ignored it, but one day it wouldn't start at all, and I had to call a tow truck. After repairs, it turned out the battery had aged—it hadn't been replaced in five years, and the insufficient power caused the relay to trip repeatedly, making a clicking sound. The technician said that in nine out of ten cases, such noises indicate a battery issue or a loose starter. He suggested testing the headlights when hearing the sound—if the lights are dim, it confirms the problem. Now, I check the battery health before winter, simply cleaning the terminals and ensuring they're tight. My personal advice: don’t delay. After replacing the battery, everything returned to normal. Regular checks save hassle—don’t make the same mistake I did by neglecting it and ending up stranded.
