Which of the following is a common cause of elevated engine vibration?

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Engine vibration is driven by forces that aren’t aligned with the engine’s mounting and drive system. When components aren’t properly aligned—such as between the engine and mounts, transmission, or accessory pulleys—the resulting uneven, rhythmic forces travel through the structure and show up as vibration. This misalignment is a common issue because mounting surfaces can wear, shift, or be installed imperfectly, and even a small offset can excite the engine frame as it runs. Imbalance is something engines are designed to minimize with balancing, so with proper balancing the vibration from imbalance isn’t as prevalent as from misalignment. Bearing wear and lubrication issues can cause roughness or noise and may contribute to vibration in some cases, but they’re typically accompanied by other signs and aren’t as frequent a standalone cause of elevated vibration.