* Age and Degradation: Rubber motor mounts are susceptible to aging. Over time, the rubber hardens, cracks, and loses its elasticity. This makes them less effective at absorbing vibrations and stress, leading to increased strain and eventually failure. 20+ years is a significant age for rubber components.
* Excessive Vibration: A poorly maintained engine (e.g., imbalanced components, worn engine mounts) or excessive engine stress can cause increased vibration. This puts extra stress on the motor mounts, accelerating their wear and tear.
* High Mileage: High mileage vehicles naturally experience more stress on their components, including motor mounts. The more miles driven, the more vibration and stress the mounts endure.
* Aggressive Driving: Frequent hard acceleration, braking, and cornering put additional stress on the motor mounts, leading to premature wear.
* Corrosion: Rust and corrosion can weaken the metal parts of the motor mount, making them more prone to fracture or failure. This is especially true in areas with harsh winters and road salt.
* Manufacturing Defects: While less common, there's always a possibility of a manufacturing defect in the motor mounts themselves, resulting in premature failure.
* Previous Accidents: If the car has been involved in a collision, the motor mounts may have been stressed or damaged, even if the damage wasn't immediately apparent.
In short, it's usually a cumulative effect of age, wear, and operating conditions that cause motor mount failure in a 1992 Bonneville. Addressing any underlying engine issues and choosing high-quality replacement mounts can help prolong their lifespan.
