Vibration. Noise. Banging. It could be a sign your car’s engine mounts need replacing, but how do you know?
We’ve explored before the effects of engine mount wear and the signs that show your car’s mounts may need replacing, but the signs of mount degradation are often easy to confuse with other problems. Engine mounts aren’t the only source of vibration in a car – a crumbled wheel bearing will create a similar issue. And there are other mounts, bushes and buffers in the car which – from dashboard to transmission – can also create noise and vibration as they degrade.
So how can you narrow the causes down to the engine mounts? The following options should help. Some of these require two people, and if you are in any doubt about your ability to perform any of the below checks, talk to a qualified mechanic.
- With one foot kept on the brake, press the accelerator. Engine movement of more than 25mm may indicate an engine mount problem.
- Depending on the model of vehicle, it may be possible to spot significant engine movement by looking for scuff marks on the underside of the bonnet or within the engine bay. If a mount wears significantly, the resulting movement could be enough to either scuff or mark the surrounding area.
- Place a solid block of wood on a floor jack and position beneath the sump. Raise the car a little at a time with the engine idling. If the vibration continues once the tyres are off the ground, it’s an indication that the vibration isn’t tracking from damaged suspension, faulty wheel bearings etc – and it’s likely to be one or more engine mounts.
Engine mount the problem but no sign of degradation?
If any or all of the above lead you to the conclusion that at least one engine mount is the problem, you might expect that mount to show some signs of degradation. But what if every mount looks to be in good condition?
In such situations look for an ‘odd one out’ – that is, a mount that, whilst it appears to be in good condition, is clearly a different brand or composition compared with the others.
If a replacement mount doesn’t have the correct vibration isolation capabilities for the application it could cause just as much, if not more, vibration as a faulty mount. A mount which, for example, employs too hard a rubber can leave the engine feeling as though it’s been bolted directly to the chassis.