What Causes the Squeaking Noise During Cold Start of a Sedan?
2 Answers
Squeaking noise during cold start of a sedan may be caused by a malfunction in the carbon brushes inside the starter motor. Below is more information about cold starts in sedans: 1. High idle speed during cold start is to allow the car to quickly reach normal operating temperature. After warming up, the idle speed will return to normal. 2. During cold start, the temperature of the coolant and exhaust pipe is low. At this time, the air-fuel mixture is rich, and some of it cannot be fully burned and is discharged through the exhaust pipe, resulting in a stronger gasoline smell. 3. Excessive carbon deposits in the intake system or at the root of the intake valves, as well as the starter motor not reaching the required speed, can all cause difficulties during cold starts of a sedan.
My old car had the same issue. The squealing noise during cold starts is most likely due to an aged and loose belt. In cold weather, the rubber hardens, causing friction between the belt and pulleys when starting. It's easy to check yourself: open the engine bay and lightly apply soapy water to the belt surface while starting. If the noise disappears, it means the belt needs replacing. Also, prolonged vehicle inactivity can worsen this issue—my neighbor left his car in the garage for three months during the pandemic, and the belt cracked completely. It's recommended to check belt tension every 40,000 km. Ignoring small issues might damage the alternator. Nowadays, replacement belts are easy to buy, and a repair shop can fix it in half an hour while also checking other pulley components for free.