Engine mounting: 3 symptoms of bad engine mounts

Arif/Jul 21, 2020 03:44 PM

Thanks to modern day sound insulation, you don’t realise how hot and bothered things are under the hood. Holding the engine in place and absorbing most of the engine's vibration are engine mounts. They take a lot of punishment. Although generally low-maintenance, engine mounts may wear out sooner than you think. Here we will discuss the symptoms of bad engine mounts in your car.

A car engine is heavy. Even a small Perodua Axia’s 1KR-VE weighs about 70 kg. A Perodua Myvi’s 2NR-VE weighs about 86 kg. A V8 1UZ Toyota engine weighs about 160 kg. All this weight is distributed across the engine mounts in your car. Some cars have more engine mounts than others.

With the engine turned off, the engine mounts only need to support a rested mass/weight. With the engine revving, the engine mounts wrestle and tame a shaking block of mass. The continuous stress and vibration of the heavy mass (engine) eventually wears out the engine mounts.

Q: How do engine mounts look like?

A: Depending on the design of the engine, their shapes may differ. Generally, engine mounts are made of rubber or polyurethane. Some engine mounts might be filled with liquids to further absorb the vibration coming from the engine.

A Perodua Axia uses three engine mounts to hold the 1KR-VE in place.

Q: What do engine mounts do?

A: They hold the engine in place and absorb the vibrations of the engine.

Q: How long do engine mounts last?

A: Generally, within 5 to 7 years. They could also wear out earlier or later so pay attention to the symptoms.

New and worn engine mounts. Photo: agcoauto.com

Q: What are the symptoms of bad engine mounts?

1. Excess Vibration. With bad engine mounts, the vibration is transferred to other areas of the car. The dashboard and doors are where you will usually see excess vibration.

Illustration exagarated to show a rattling dashboard.

2. Impact noises. Bad mounts will cause the engine to twist and collide with other things in the engine bay. This is usually more noticable when you shift from "D" to "R" and the other way around.

3. Misalignment of the engine. A quick visual inspection of the engine bay is all you need to spot a misaligned engine. With a broken mount, the engine may droop to one side.

Q: Can engine mounts be fixed?

A: No. They need to be replaced.

Q: What causes engine mounts to break/wear?

They age. Wear may be accelerated if the mount is exposed to hot oil.

Driving too fast over bumps also increases the stress on the engine mounts. Head-on collisions could also potentially damage the engine mount or cause misalignment.

A 20 year-old engine mount. Photo: Chris Fix

Q: What happens if you don’t change the engine mounts?

A: Since the engine becomes freer to move, you risk damaging the hoses and belts in the engine bay. There is also potential of serious damage to the engine due to excessive bouncing.

Q: Do some engines vibrate more than others?

A: Yes. 3-cylinder engines vibrate more than 4-cylinder engines. Generally, odd-number-cylinder engines are harder to balance than even-number-cylinder engines. Just look at how a brand new Axia engine vibrates. 

No matter how balanced an engine is, there is still significant vibration absorbed by the engine mount.

Q: Is there anything you can do to extend the life of engine mounts?

Not much. Mainly try not to get into a head-on collision, and don’t drive too fast over speed bumps. You can also check under the hood to make sure no oil is dripping onto the engine mounts. Even with these steps, you will not be able to extend the life of the engine mount significantly.

In summary, engine mounts last between 5 to 7 years. Symptoms of bad engine mounts include excess vibration, impact noises (thud/clunk), and misalignment of the engine. Although generally fuss-free, keeping your engine mounts in check helps to avoid further damage caused by a loosely-held or bouncing engine.