7 unusual car noises you shouldn't ignore
Published on: Tuesday, 8th October 2019 | 
Author: Tyre Pros
Hearing an unusual noise when you’re driving at speed can be heart-stopping. Most of these noises are nothing to worry about, but some should not be ignored. If you hear any of the following, take action as a matter of urgency:
1. Knocking from the engine
A knocking sound from deep within the engine is never good news. It could be simple to fix with a top up of engine oil to lubricate the moving parts properly. However, a distinct knocking noise could also signal that a key engine component has broken, or is just about to break.
Don’t panic if you hear a soft ticking sound, as some car engines make this noise due to the working of their electrical systems. If it’s a loud knocking you can hear though, it’s definitely time to head to your local garage for a check-up.
2. High pitched squealing during accelerating
A squealing sound as soon as you set off usually means that your fan belt is loose or worn. The belt deteriorates over time and may eventually need to be replaced or it could do serious damage to your car engine and other parts. A trained mechanic can tighten up your fan belt if it’s loose, which should stop the noise. If the belt is worn, you’ll need to spend some money on a new one.
You won’t fail to notice this kind of noise, as it’s so high-pitched and happens as soon as you start to accelerate. Don’t continue driving for too long without getting the issue diagnosed, as it could lead to a breakdown.
3. Hissing
No vehicle should hiss, under any circumstances. This is not a normal noise, so you shouldn’t ignore it. Hissing coming from the engine usually means that one of the rubber hoses has a crack, hole or other failure. Hoses carry everything from engine coolant and air to hydraulic fluid to keep your car running smoothly. A hiss often means that air or steam is being forced through a newly formed crack.
The rubber hoses in your engine will deteriorate over time, but they shouldn’t be too expensive to replace. The tricky part will be identifying where the leak is coming from. You’ll need to listen carefully for the hissing sound, just like when trying to find a puncture in a bike tyre. It’s best to call in the professionals, who can do some detective work and fix the problem.
Hissing could also be a sign that the engine is overheating, which you can confirm by checking the temperature gauge and looking for steam coming from under the bonnet. If you see steam or an engine overheating warning comes on, don’t continue driving. Find somewhere to safely pull over and call for help while waiting for your engine to cool down.
4. Bangs
A loud bang is not a good sign. You’ll find it hard to ignore such an alarming noise, but stay calm if you hear it while driving. A bang could be a sign of your engine backfiring, potentially caused by a clogged air filter preventing air from mixing with the fuel supplied to the engine. It could also be down to a problem with the catalytic converter. Either way, it’s best to get your car in for inspection as soon as possible after hearing such a noise.
5. Squealing, grinding or scraping when you apply the brakes
Your brakes are absolutely essential for safe driving and full control behind the wheel. The occasional squeal when you press the brake pedal isn’t an urgent issue that needs to be fixed on the spot, but you shouldn’t leave it too long. It could mean that the brake pads are worn, or something more serious.
Never ignore a grinding or scraping noise when you brake, or even when your feet are nowhere near the pedals. This is an indicator that the problem has progressed, and the metal parts are touching each other. If you ignore the squealing, it’ll soon turn into a grinding or scraping and this may be a much bigger, more expensive repair.
6. Any noise when changing gears
It should be smooth and easy to change gears, and you shouldn’t hear any noise. If there’s a clunking or any other loud noise when you change into a new gear, this could be a sign of trouble. The transmission system could be the culprit, or it could be a damaged clutch. Arrange to get some diagnostic tests carried out right away, as it could turn out to be a serious problem. Ignoring it may prove very expensive when it comes to repairs.
7. Rattling
Pinpointing the cause of a rattling noise means finding where the sound seems to be coming from. Does it sound like it’s underneath the car, or even underneath your feet? If you hear a noise like a box of rocks being shaken underneath the vehicle, this could mean a problem with the exhaust system. Specifically, the catalytic converter may need replacing. You’re more likely to notice such a noise when the car is idling, as there’s no car-on-tarmac noise to drown it out.
As well as rattling, you should also listen out for a sudden increase in the volume or throatiness of the sound your exhaust makes. If one day it sounds far louder, even inside the car, it means there is a serious issue that needs investigating.
Try not to panic if you hear an odd noise
You know your car and the noises it usually makes. There’s no need to panic unnecessarily if you do hear a new noise, but you shouldn’t ignore it. Complete your journey if you can (unless it’s a bang or a hiss indicating a serious fault) and then make an appointment at your nearest garage. Some unexplained noises turn out to be quick, easy fixes, while others can be costly. It’s all part and parcel of owning a car.