Engine mount: how it works, symptoms, problems

May 10, 2015
Engine mount
Engine mount. Click for larger photo
Top engine mount
Top engine mount in Hyundai Elantra

An engine mount is the part that holds the engine in your car. In a typical car, the engine and transmission are bolted together and held in place by three or four mounts. The mount that holds the transmission is called the transmission mount, others are referred to as engine mounts. One part of an engine mount is bolted to the car body or frame. Another part holds the engine.

An engine is a source of vibration, as it has many moving and rotating parts. One of the main jobs of an engine mount is to reduce the engine vibration felt inside the car. Engine mounts are filled with rubber so that there is no direct metal-to-metal contact between the engine and the car body. To further dampen the vibration, some engine mounts are filled with liquid. A liquid-filled engine mount acts like a shock absorber.

Some car manufacturers (e.g. Toyota, Honda) use active vacuum-controlled engine mounts that vary dampening as needed. Porsche offers electromagnetic mounts to actively reduce engine vibration transferred to the body.

An engine mount doesn't need any maintenance or regular servicing. It only needs to be replaced when it fails or wears out.

Engine mount problems

New vs broken engine mount
New vs broken engine mount.
Leaking engine mount
Leaking engine mount

The most common problem with the engine mount is when the rubber part breaks or separates or when liquid starts leaking out of the liquid-filled mount.

Common symptoms of a failed engine mount is the increase in engine noise and vibration felt inside the car. Often, the excessive vibration is more noticeable at idle with the transmission engaged. For example, in some 07-08 Honda Civic models, a failing passenger side mount can cause a vibration and growling noise felt in "Reverse" when the engine is started cold. In Mazda 3, a broken top engine mount can cause vibration at idle, especially noticeable when the transmission is in "Drive".

In some cars, a broken engine mount can also cause a noticeable jolt or "thump" when shifting into "Drive" or "Reverse" or when

accelerating or decelerating. In Honda Odyssey, for example, a failed engine mount can cause harsh transmission engagement when shifting between "Park", "Drive" and "Reverse" as well as vibration at highway speeds.
Early signs of a failed engine mount include visible cracks and separations in the rubber and leaking liquid.

Replacement costs vary. For example, the top engine mount replacement in Mazda 3 costs $150-$215, while for two broken mounts in Honda Odyssey the dealer quoted us $1,800 parts and labor. Aftermarket parts are cheaper, but there are reports about some aftermarket mounts failing prematurely or causing more vibration. When using an aftermarket part, do some research on part quality. For example, we searched for the engine mount for the 06-11 Honda Civic on Amazon and found several brands with ratings ranging from 3 to 4.5 stars. Obviously, it's worth to pay a little more for a better-rated brand.

For many cars, an engine mount is covered by the Powertrain warranty, you can verify this in your car's warranty booklet.