If engine vibration is present, the most likely damaged component is which of the following?

• A. Bad transmission bearing
• B. Damaged vibration dampener
• C. Excessive fuel injection
• D. Poor fuel injection

Answer: (B)

Engine vibration comes from the crankshaft’s torsional motions, and the vibration dampener (harmonic balancer) is the component that absorbs and cancels those vibrations before they spread through the engine and into the rest of the vehicle. If the dampener is damaged, its ability to dampen these torsional vibrations is lost, so the engine vibration becomes noticeable. The other options don’t directly address the source of engine-wide vibration: a bad transmission bearing causes drivetrain-related vibration and noise rather than crankshaft vibration, and fuel injection issues lead to rough running, misfires, or irregular idle rather than a prominent, consistent vibration through the engine itself.