What Causes the Whining Noise When Coasting in Gear with Throttle Closed?
2 Answers
This issue often occurs when there is insufficient torque. Most common abnormal noises in the engine depend on the engine's speed condition. 1. Causes of the noise: Excessive clearance between the piston and cylinder wall; Overly tight piston pin or connecting rod bearing assembly; Excessive clearance between the tappet and its guide hole; Wear on the camshaft profile; Sometimes, a loose starter pulley can cause noise (especially noticeable during speed changes). 2. Identification method: Many abnormal noises in the engine are clearly related to its load. During diagnosis, the method of gradually removing the load can be used for testing. Typically, the single-cylinder or double-cylinder misfire method is employed to remove the load from one or two cylinders to identify the relationship between the noise and the load.
The issue of whining noise when coasting in gear with the throttle closed is something I frequently encounter at the repair shop, and there are quite a few potential causes. Primarily, it's due to aging components in the drivetrain, such as worn differential bearings or increased gear clearance, which generate vibrations and noise when transmitting power. Loose or insufficiently lubricated universal joints on the driveshaft can also produce this whining sound. Additionally, unbalanced or worn tires can resonate and create similar noises during coasting. Insufficient transmission lubrication or degraded fluid may affect the internal component alignment. It's advisable to visit a professional workshop immediately for inspection. Have the vehicle lifted on a hoist so the mechanic can carefully pinpoint the source of the noise—don’t wait for a minor issue to escalate. Regular maintenance is key: don’t skip scheduled transmission fluid changes and tire balance checks, as these can effectively prevent such problems, ensuring a smoother and worry-free ride.
