Motor (Engine) Mount

Motor mounts are used to secure the drivetrain to the vehicle frame, or chassis. They come in various shapes and sizes, and nearly every vehicle has at least two. Front wheel drive vehicles with transversely mounted engines will have a motor mount on the side of the transmission as well. This particular mount can be called a motor mount because the motor and transmission are bolted together, meaning the mount will still hold the weight of the motor. If a mount is underneath the transmission completely, this is commonly called a transmission mount.

Most modern motor mounts use a liquid filled core, which is contained by a composite rubber material. This allows the mount to flex as needed while still preventing the vehicle from absorbing the vibrations and noise from the engine. This composite rubber insert, also called the insulator, is encased in a metallic housing to provide a firm, stable mounting surface for the engine and transmission.

Symptoms of Wear or Failure of Motor/Engine Mounts

  • Excessive engine vibration, which can be felt inside the vehicle
  • Clunking noises when the transmission is shifted between drive and reverse for automatic transmissions, or when releasing the clutch pedal for manual transmissions.
  • Excessive engine movement, even if a clunking noise is not heard
  • Front wheel drive vehicles may experience repeated CV axle or CV boot failure
  • Increased engine noise in the vehicle

Related Repair Advice on Motor Mounts

  • As with all rubber components, dry rot and flexion deteriorate the integrity of the motor mount over time, and most motor and transmission mounts will need replacement during the normal life-cycle of the vehicle
  • Motor mounts on many older vehicles can be disassembled, so the composite rubber insert is replaced in lieu of the entire mount
  • A broken motor mount allows the engine and transmission too much movement and can cause potential damage to components that depend on a stable engine, including axles, wiring harness, driveshaft universal joints, exhaust systems, fuel and EVAP system lines, and any components with low clearance between the engine and the vehicle
  • Many aftermarket motor mounts are advertised for performance applications will create excessive engine noise and vibration due to the hard composition of the rubber insert. They can increase the performance of a vehicle, so long as passenger comfort is not a concern
  • Excess engine movement caused by a failed mount can damage other mounts. When a failed motor mount is replaced, the other mounts should be inspected for damage
  • Motor mounts, as described above, hold the weight of the engine, therefore, the engine should be properly supported from above when changing an engine mount. This will help prevent damage to components and injury.
  • Never support an engine by placing anything underneath the engine oil pan. Oil pans are either thin or brittle, and are not designed to hold the weight of the engine on a small area such as a jackstand. Engine braces are commercially available in most locations

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