10 Worrying Car Noises and What They Could Mean

Driving is very much a sensory experience, cars are visually stimulating objects to admire and some, impressionable to hear. Sometimes they can even give our nostrils a blast, think of the smell of petrol and new car smell hmm… In terms of driving on the limit, a racing driver’s ability to process their senses at hyper speed is critical to understanding the car and ultimately winning. But what about day to day driving? Recently my Mk4 Golf GTi developed a drone like noise from 30mph onwards. I suspected this could be because of the front wheel bearings as in my old family car, a Renault Laguna, a similar noise came from a back wheel and as it turned out it was because of the front wheel bearings! I do love being right. Having a basic knowledge of what noises to look out for could save you a lot of money and prevent a serious accident waiting to happen. So here are 10 worrying car noises and what they could mean. You’re welcome!

1 – Humming drone like sound that increases with acceleration

As I have already mentioned, this is likely to be down to your wheel bearings. But what are wheel bearings? Well they’re basically little lubricated balls – hilarious! They connect the axle and wheel enabling the wheel to rotate smoothly and reduce friction. But over time they can wear down; oscillations from the bearings can damage the rest of the wheel assembly and eventually the bearings themselves can seize up and lock, leading to a potentially disastrous accident. Replace your bearings!

A roaring drone like sound could also be the gearbox, changing gear and listening for a change in the sound is a good way of distinguishing between the two. Similarly, the drone like sound should get worse as you corner and hard cornering can excessively wear the wheel bearings. Although I imagine in my case it’s because of the high mileage on the Golf…

2 – Screeching when braking

Have you ever been embarrassed by your eerily screechy bicycle brakes? I sure have. Screechy brakes mean worn brake pads, and just like a bicycle, car brakes have pads too. Road cars can either have drum brakes or pads and discs. Most modern cars are fitted with pads and discs but screeching can also come from a drum brake if the brake shoes are worn.

Brakes can sometimes screech if they’re wet, new or haven’t been used for a while, so it doesn’t necessarily mean that they’re worn. You may not necessarily feel that you have less braking power, as over time you’ll gradually be putting more brake pressure through the pedal to compensate. Being able to stop a tonne of metal is important for the health and safety of whoever’s in or out of the car. Duh! So if your brakes are screeching a lot you should probably get them checked out.

3 – Popping from the engine

Spark plugs make the fuel in your engine go bang! An electrical current is sent to them lighting up the fuel/air mixture just at the right time as the cylinder reaches the top of it’s cycle. As you can imagine, these little fire starters are going off thousands of times a minute in correlation to the revs of your engine. So inevitably they’re not going to last forever.

Their can be a whole host of reasons for hearing some pops from your engine but it’s likely to be because of a worn out spark plug. They can cost as little as £2-5 individually so it’s not the end of the world. Although it can be a pain to take your car to the garage and you will have to pay for labouring costs, you don’t want to be driving with faulty spark plugs for very long. It will reduce the engine’s power, increase fuel consumption from not properly burning all the fuel, and could cause long term damage to the engine.

4 – Hissing under the hood

If you can hear hissing you should probably pull up somewhere, turn the engine off, and work out what the hell’s going on! The chances are you’ve got a leak. It could be coolant, oil or transmission fluid. A warmed up engine is typically around 90 degrees so any liquid leaking onto it is going to make a steaming hiss. You should call up your breakdown cover and get a toe too, as a leak could seriously mess up a car’s electronics. Remember to check the various liquids and oil under the bonnet and keep them topped up; and triple check the various caps are tightened!

5 – Whirring sound under the car

If you can hear a whirry sound under the car that’s in time with the engine, the chances are you’ve got a crack or hole in your exhaust manifold. Although exhausts may seem like a less crucial car part, a faulty exhaust can effect the performance of the engine. It can also release harmful Carbon Monoxide gases if the crack/hole occurs before the catalytic converter (nasty gas filter). Similarly, if your engine is particularly loud, the chances are you have a hole in the exhaust.

6 – Thump Thump Thump noise, probably a flat tyre?

Yeah probably. This should be obvious though, if you feel vibrations coming from any of the wheels they’re probably deflated of have a flat spot. If your car doesn’t have ABS and you’ve had to do an emergency stop, you may have locked the wheels and shaved off a sizeable chuck of tyre (flat spot). Each time a flat spotted tyre rotates the wheel’s going to jolt and that’s not good for the handling of the car or the wheel assembly.

Keep an eye on your tyre pressures every few thousand miles to spot early signs of a puncture and remember, hard cornering, wheel spinning and even hard braking can wear down your tyres. A new tyre has up to 9mm of tread depth and legally you’ll need at least 1.6mm across 75% of the tyre. Although 1.6mm of tread won’t do a lot of work for you in heavy rain and you could easily aqua plain so get them changed if there’s only a few mill left.

7 – Flapping noise

If you can’t spot a problem with the tyres, the flapping is likely to be because of a loose fan belt. A fan belt is responsible for keeping the engine cool by not just fanning it, but also running the water pump. An overheated engine is not good at all. It could permanently damage the engine, completely writing your car off, yikes!

8 – High pitched squealing

This is also because of the fan belt. Not much else to say really other then fan belts can squeal, flap and break the bank if you don’t replace them. Dam fan belts.

9 – Clicking sound under the hood

This should be a very faint click so you shouldn’t be able to hear it with the radio on. But this is either because of a lack of engine oil or low oil pressure (fault with the oil system). Top up the engine oil if it’s low, a 1 litre bottle is good to chuck in if it’s very low or empty (remember to check your car manual to find the correct type). Give the car a good blast on the motorway to let the oil get stuck in, and check the level a day after when the engine is cool. If the level’s good and you can’t hear any clicking and there are no obvious signs of leaking underneath, all is good. Hurrah!

If the clicking’s still there, and the level’s okay there’s a good chance something’s wrong with the oil system and the oil isn’t circulating properly. S**t. This means there’s a blockage and the engine’s probably done for. If it’s not that it could be a problem with the valve system which can be fixed but if this is the case, it’ll definitely cost more then the worth of the car.

10 – Knocking sound in the engine

You’ve probably put the wrong fuel in. I’m not talking about getting confused with petrol and diesel. If you get them mixed up, your car will start to facetiously judder or won’t start at all! Also you’re an idiot. Petrol comes in various octane levels but in the UK it’s typically 95. This shouldn’t be a problem at most UK petrol stations but do double check each time you fill up. Lower octane fuels will cause the engine to knock if it hasn’t been designed to work with a low octane fuel. Check your car manual but you should equally avoid using higher octane fuel then your car needs as you’ll waste money.

In performance cars you’ll need to use higher octane petrol or premium fuel. There isn’t a real octane difference between diesel fuels but it’s still good to use premium diesel every now and then. With older cars especially, it can be a good idea to fill up with a full tank of premium fuel, petrol or diesel, once in a while. Premium fuel is great for keeping the engine clean and can help improve the life expectancy of the engine. Think of it like one of those multi vitamin healthy boost your immune system juices for your car. It’ll thank you for it I’m sure.

So there’s 10 worrying car noises and what they could mean, I hope you found this useful. If you constantly listen to the radio you might want to drive without it every now and then to check on your car. There aren’t many smells to look out for other then burning and perhaps a questionable passenger fart. I guess a smelly air con system is an indication you might need a new air con filter; and don’t forget, if you can see flame or smoke, you might want to get out and run! Drive safe people.

By James Drujon