Why is there abnormal noise during cold start?
2 Answers
Reasons for abnormal noise after cold start: 1. Belt aging: The generator belt ages, and its rubber material is affected by thermal expansion and contraction. When the car is cold, the belt contracts, and daily rotation stretches the belt, which can easily cause the belt to slip during cold start, producing noise. 2. Valve tappet: Due to the valve tappet, during cold start, engine oil is pressurized from the oil pump into the engine oil passage before reaching the valve tappet, which can cause increased noise during cold start. 3. Loss of lubrication: The internal gears of the starter lose lubrication, causing sticking and affecting the timely return of the gears. 4. Carbon brush failure: The carbon brush inside the starter motor malfunctions.
I've been driving for over a decade, and it's common to hear strange noises when starting the car after it's been parked for a while in winter. The main reason is that the oil inside the engine thickens when the car is cold, flowing more slowly. Especially in the morning, when the oil hasn't fully pumped to the components, parts like pistons and bearing shells can grind directly, causing creaking sounds. Another common issue is the belt, such as the one for the alternator or air conditioning. If it's aged, loose, or covered in dust, it may squeak under the tension when the car starts. Carbon buildup can also cause trouble. If left uncleaned for a long time, deposits in the intake pipe can restrict airflow, making valve operation less smooth and increasing noise during acceleration. It's important to develop good habits: change the engine oil regularly and choose the right viscosity grade; check belt tension every six months and replace it if it's aged; don't neglect engine maintenance. Small issues left unattended can lead to bigger problems, like increased engine wear or even part failure, which can be costly and labor-intensive to repair. It's better to visit a professional shop early to avoid headaches.
