What Causes the Clicking Sound When Starting a Cold BMW 3 Series?
1 Answers
BMW 3 Series produces a clicking sound during cold starts due to the small clearance between the gasoline engine pistons and cylinder walls. Reasons for Cold Start Noise: The noise during cold starts occurs because components are cold and rigid, with insufficient lubrication, leading to abnormal sounds. Additionally, sudden acceleration when drive wheels slip can cause planetary gears to seize on their shafts. Effects of Cold Starts: A cold start refers to starting the engine after it has been off for a period, during which the engine has cooled down significantly below its normal operating temperature, and engine oil has mostly drained back. Over 80% of engine wear occurs during the cold start phase.