What is the likely cause if a car makes noise while in gear with the clutch disengaged?

If a car makes noise while in gear with the clutch disengaged, the likely cause is a dry pilot bushing. The pilot bushing, which is located in the flywheel or crankshaft, supports the end of the transmission input shaft and allows it to rotate freely. When the clutch is disengaged, the transmission input shaft should ideally not be spinning, but if the pilot bushing is dry or worn, it can cause the shaft to vibrate or produce noise as it may lack sufficient lubrication or support.

This noise indicates that there is a problem with the pilot bushing's ability to perform its function properly, leading to potential damage and wear of the transmission components over time if not addressed. Proper lubrication and maintenance of the pilot bushing are essential to ensure smooth operation and to prevent noise in the transmission when the clutch is disengaged.