Engine Mountings are made of steel and rubber. Time, heat, automotive chemicals and vapours will deteriorate the rubber. When the rubber deteriorates, the vibrations begin to be felt. 

Worn engine mountings often can have a few effects.

1) Aggravation of increased engine noise and vibration.

2) Binding of linkages: i.e. throttle and some transmission related controller linkages. These can show themselves in what appears to be increased pedal pressures or slower responses to driver inputs.

3) Steering wheel vibrating during stationery.


In the worse possible case, the throttle linkage can be jammed, resulting in unintended acceleration. On vehicles with a belt-driven, water pump mounted fan, a broken mount may cause the engine to rotate forward and puncture the radiator with the fan blades.