What causes abnormal noise when starting the car?

1 Answers
VonDaniel
07/30/25 2:03am
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.
Was this review help?
18
4
Share
More Forum Discussions

Should Car Windshield Washer Fluid Be Diluted with Water?

Whether car windshield washer fluid should be diluted with water depends on the specific situation: 1. Non-concentrated washer fluid is already pre-mixed and does not require water dilution; 2. Concentrated washer fluid needs to be diluted with water. The method for adding car windshield washer fluid is: 1. Open the front hood; 2. Open the washer fluid filler port; 3. Fill with washer fluid until reaching the marked level. The performance and characteristics of washer fluid are: 1. Cleaning performance: Composed of various surfactants and additives, surfactants have wetting, penetrating, and solubilizing functions; 2. Antifreeze performance: Significantly lowers the freezing point of the liquid; 3. Anti-fog performance: Forms a single-molecule protective layer on the glass surface.
4
0
Share

What causes the jerking sensation when accelerating at low speeds in an automatic transmission car?

Automatic transmission cars experiencing jerking or surging during low-speed acceleration are often caused by engine-related issues. Additional details are as follows: 1. Engine function: Ignition, air intake, and fuel injection jointly determine fuel combustion, which is the power source of the engine. If the air intake decreases, ignition weakens, or fuel injection reduces, insufficient power output occurs, resulting in jerking sensations. 2. Situation explanation: Some jerking during automatic transmission vehicle acceleration is normal. For rapid acceleration, deep throttle application is required, causing the automatic transmission to downshift and increase engine RPM. When RPM reaches a certain level, upshifting occurs. Since RPM drops significantly after upshifting, relatively noticeable jerking may occur. This phenomenon is more common in automatic transmission models with fewer gears, such as 4-speed automatics. For smooth driving after starting an automatic transmission vehicle, gently pressing the accelerator pedal at appropriate times allows the transmission to upshift with minimal jerking. For better acceleration performance, deeper throttle application is needed, causing the transmission to upshift at higher speeds with more noticeable gearshift jerking.
12
2
Share

What are the steps to replace the air conditioning filter in the Lavida?

The steps to replace the air conditioning filter in the Lavida are: 1. Remove the black plastic panel above the footwell on the passenger side; 2. Disconnect the negative terminal of the battery, remove the body control module, and take off the bracket that secures the body control module; 3. Press the clips on both sides of the air conditioning filter and pull out the old filter; 4. Install the new air conditioning filter in place. The Lavida is a compact car produced by SAIC Volkswagen. Taking the Lavida 2021 280TSI DSG Comfort Edition as an example, its body dimensions are: length 4670 mm, width 1806 mm, height 1474 mm. The Lavida 2021 280TSI DSG Comfort Edition is equipped with a 1.4T turbocharged engine and a 7-speed dual-clutch transmission.
20
0
Share

How to Replace the Taillight of a Sonata?

The method to replace the taillight of a Sonata is: 1. Open the trunk lid, disconnect the vehicle's power supply, and clean the trunk; 2. Remove the dust cover at the back of the taillight; 3. Identify the taillight that needs replacement, press and hold the rotating handle at the rear of the taillight, then unscrew it; 4. Install the new taillight and reassemble the taillight and dust cover. The Sonata is a mid-size car launched by Beijing Hyundai. Taking the Sonata 2020 270TGDi GLS DCT Premium as an example, its body structure is a 4-door, 5-seater sedan with dimensions of 4955mm in length, 1860mm in width, and 1445mm in height, a wheelbase of 2890mm, a fuel tank capacity of 60 liters, and a curb weight of 1455kg.
20
0
Share

What does the tire specification 205/60r1692v mean?

The meaning of tire specification 205/60r1692v is: 1. 205 represents the tire width; 2. 60 indicates the aspect ratio, which is the tire thickness; 3. r16 is the diameter of the wheel rim; 4. 92 represents a load capacity of 630 kilograms; 5. v indicates the tire speed rating of 240 kilometers per hour. Tires are circular elastic rubber products mounted on metal rims that roll on the ground and are assembled on various vehicles or machinery. They support the vehicle body, cushion external impacts, maintain contact with the road surface, and ensure driving performance. Precautions for tire use include: 1. Regularly check whether the tire pressure is normal; 2. Promptly remove stones stuck in the tire grooves; 3. Regularly inspect tires for cracks and wear, and replace them in time; 4. Look ahead while driving to avoid entering areas with nails; 5. Inflate tires promptly if they are slowly losing air.
1
1
Share

What Causes the Car Anti-Skid Light to Illuminate?

The reasons for the car anti-skid light illuminating are: 1. Accidentally pressing the ESP OFF button; 2. Loose or faulty sensor connectors; 3. Short circuit in the wiring or blown fuse; 4. Software issues causing poor signal transmission; 5. ABS pump failure. Methods to turn off the car anti-skid light include: 1. Restarting the engine and briefly pressing the ESP OFF button on the vehicle; 2. Taking the car to a 4S shop for inspection and using a specialized fault diagnostic tool to locate the issue; 3. Using a decoder to clear the fault code. The working principle of the anti-skid light is: Through the ASR electronic control unit, based on signals from the vehicle's wheel speed sensors, the slip rate of the wheels and the vehicle's driving speed are calculated and analyzed. The electronic control unit then adjusts the throttle opening and brake pressure to regulate the wheel slip rate, preventing the vehicle from skidding during driving.
18
2
Share
Cookie
Cookie Settings
© 2025 Servanan International Pte. Ltd.