Symptoms of a bad motor mount

Vibration and noise, engine movement, and rough running are signs of a failing motor mount

typical motor mount on a late model vehicle

As an engine creates torque, there’s always an equal-and-opposite-reaction to the torque twist. To keep the engine in place and resist twisting, carmakers secure the engine and transmission with motor mounts and at least one transmission mount. Over time and miles, motor mounts can fail. This article deals with the symptoms of a bad motor mount.

To learn more about the four different types of motor mounts and how they work and fail, see this post

In a traditional engine engine, there’s a motor mount on the right and left side of the engine. However, in a transverse mount engine that can be three or four motor mounts.  See this post on how motor mounts work and how they fail.

Bad motor mount symptoms

Noise and vibration — A worn motor mount transmits noise and vibration to the cabin

A motor mount is designed to absorb engine vibration and prevent it from transferring to the body of the vehicle. When it fails, you’ll hear more engine vibrations in the cabin. The noise will be directly related to engine RPMS.

A bad engine mount can also make a thumping or clunking sound that’s most noticeable as you shift into or out of gear because the engine twists quite a but when it’s engaged in D or R.

Excessive engine movement is always a symptom of a bad motor mount

You can see engine movement. Have a friend help you check for excessive engine movement. Simply apply the brakes and put the engine into D or R and add slight acceleration. The engine should move slightly. But if it looks like the engine is about to rotate itself out of place, that’s a symptom of a bad motor mount.

Visual symptoms of a failed motor mount

All motor mounts incorporate a rubber cushion between the mounting surfaces. Over time, the rubber ages and cracks and can even completely separate from the metal mounting plates. If the motor mount is fluid-filled, it can leak and deflate, causing the engine to sag on the side of the failed mount.

Typical motor mount failures

Once a motor mount fails, the engine can rotate opposite to the torque force, causing hoses, fuel lines, and electrical harnesses to stretch or move beyond their limits. This can cause hose failures, electrical problems and even fuel leaks.