Gaskets, cylinders, coil-packs and lambda. Whether you're trying to decipher your favourite TV motoring show or aiming to better communicate with your mechanic to spruce up the car you are selling or buying, it pays to learn some of the most commonly used lingo. We sat down with Aaron Borrill, senior car journalist and blogger, to find out what some of the most common issues are - plus the warning signs to watch out for.
Common issues for owners of second-hand cars
Blown head gasket
Warning signs: Black smoke from your exhaust, engine overheating, loss of power
"The gasket is a seal between the engine head and the engine block. Sometimes, after years of use, a crack can develop in the engine head and this could lead to gasket problems. For example, coolant from the cooling system that cools your engine can sometimes seep into the cylinders (the cylinder is where combustion happens, making the engine run). Problems this could cause include:
- Compression loss, i.e. your car will have less power than usual.
- Engine overheating - look out for steam or smoke from your engine and monitor your engine's temperature gauge.
- More wear on your engine because of your oil mixing with the antifreeze that keeps your water from freezing in winter."
Run a wheel bearing
Warning signs: Creaking, grinding and clicking noises
"Bearings are all-important in making your wheels run smoothly. Remember: wheels are general wear and tear items that see a lot of action in driving and cornering situations. If regular checks are not carried out and you continue to drive your car without changing your tyres - especially when the wheels start making these noises - the bearing will overheat and, eventually, the wheel could break off. And you really don't want that to happen!"
Warning signs: Excessive revving without noticeable acceleration
"A slipping clutch happens when you are abusing your clutch, for example when you are waiting at a red light on a steep hill and riding your clutch. It could also be because of a worn clutch plate, friction point and oil contamination, and should be fixed before more wear and tear occurs."
Warning signs: A jerking sensation from the engine or a rough diesel-sounding engine note
"A misfire could happen for many reasons:
- A loss of spark from the spark plug or coil-pack. You get coil packs in some modern cars - they are similar to spark plugs in that they are used to create the spark for the ignition of the mixture in each cylinder.
- A faulty fuel injector not injecting the correct amount of fuel.
- A loss of compression caused by worn ring seals, which you'll find on your pistons, sealing the gap between your cylinder and piston."
Common issues for new car owners
Warning signs: Jerking and loss of power
"In modern cars, the air-flow meter measures the amount of air which enters the intake manifold - the place where air enters the combustion chamber. It also communicates with the engine control unit to adjust the fuel injection accordingly. When the air meter is faulty, this can lead to problems with the timing of the ignition, which causes this jerky feeling and a loss of power."
Turbocharger, turbo manifold and your exhaust system
Warning signs: Lack of power
"There are a few things in new cars which can cause issues with your exhaust system:
- Turbochargers: These boost a car's performance by force-feeding more air into the combustion chamber (the part of the engine where combustion happens, i.e. the cylinders). This forcing of air into the cylinders creates a bigger explosion and ultimately increases power output and performance. Turbos can also reduce fuel consumption due to some clever trickery in the engine control unit. Sometimes the turbo can 'blow' or develop a crack in its casing because of these very high temperatures from compressed air. Sadly then the opposite happens, you actually get a lack of power and efficiency.
- A blocked catalytic convertor (cat for short): A 'cat' filters harmful exhaust particles and can become blocked over time.
- Faulty lambda sensor: This sensor balances the fuel mixture, i.e. leaning the mixture when the sensor reads 'rich' and enriching the mixture when it reads 'lean'."
Visit our car advice page for more useful tips.