The most common causes of call-outs reported by the motoring organisations vary slightly each year, but averaged out over the last few years, the top 10 causes of breakdowns are as follows.
1 Flat or faulty battery
To help to avoid problems:
- Check the battery terminals regularly, make sure that they’re secure and keep them free from corrosion. Most car accessory shops sell battery terminal protector spray, or you can use petroleum jelly or grease instead.
- Keep the top of the battery clean and dry.
- If you make lots of short journeys, take your car on a long journey every once in a while, which will help the alternator to charge the battery.
- Make sure that all the electrical equipment (lights, heater blower, heated rear window, etc) is turned off before you try to start the engine.
- Check the alternator drivebelt once in a while.
- At the first sign of trouble, such as difficult starting, dim headlights, or if the charging warning light comes on, have the battery tested.
2 Flat or damaged tyres or wheels
To help to avoid problems:
- Check the tyre pressures and the condition of the tyres regularly. Don’t forget the spare.
- Make sure that if you’re carrying a heavy load you adjust the tyre pressures to the recommended ‘full-load’ pressures, and that you return them to normal when you’ve unloaded.
- If you ‘kerb’ a wheel when parking or driving, check the condition of the wheel and tyre as soon as possible afterwards.
- Consider carrying a can of tyre ‘instant repair’ foam.
- Make sure that the jack, wheel brace and (where applicable) the key or removal tool for locking wheel bolts, are in the car and that you know how to use them.
3 Alternator faults
The alternator’s job is to charge the battery, and if the alternator fails, the battery will soon fail too. The telltale signs of a problem include:
- Frequent battery problems and dim headlights when the engine is ticking over.
- A squealing sound from the engine compartment, which may indicate a slipping alternator drivebelt.
- A glowing charging warning light (usually orange), especially when the engine is ticking over.
- Stop as soon as possible if the charging warning light comes on when you’re driving.
4 Starter motor failure
The following signs are likely to indicate that the starter motor has failed:
- Metallic noises when trying to start the engine.
- The engine turns more slowly than usual when you try to start it (might also indicate a battery problem).
- A click can be heard from the engine compartment, but the engine doesn’t turn over when the key is turned to the ‘start’ position (might also indicate a battery problem).
5 Ignition distributor cap or rotor arm problems
Many modern cars don’t have a distributor cap, so this may not apply to your car. It doesn’t apply to cars with diesel engines. To help to avoid trouble, make sure that the distributor cap and rotor arm are checked when your car is serviced. The telltale signs of a problem include:
- Misfiring of the engine, especially when accelerating or driving uphill.
- Difficulty starting the engine, especially in damp weather.
6 Running out of fuel or filling with the wrong type of fuel
Both of these problems are easily avoidable, provided you take the following precautions:
- Fill up with fuel before a long journey.
- Keep an eye on your fuel gauge, and don’t wait until the warning light comes on before filling up. Fuel gauges can be notoriously inaccurate!
- If you’re travelling on a road where fuel stations are scarce, make sure you have enough fuel to make it to the next large town where there’s likely to be fuel available.
- If you’re driving a new car, or you’ve hired or borrowed a car, make sure you know what type of fuel it takes, and always make sure that you’ve selected the correct fuel pump (petrol or diesel) before starting to fill up.
7 Damage to clutch cables
This only applies to cars with a manual gearbox, and even then some cars have a hydraulic clutch which doesn’t use a cable. If the clutch cable breaks, you won’t be able to change gear – nothing will happen when you press the clutch pedal.
To help to avoid trouble, make sure that the clutch cable is checked when your car is serviced. Telltale signs of a problem include:
- The clutch feels ‘strange’ when you press the clutch pedal, or the pedal seems to be higher or lower than normal when in its rest position.
- The gears crunch when changing gear.
8 Worn out spark plugs
This only applies to cars with a petrol engine. To help to avoid problems, new spark plugs should be fitted at the intervals recommended by the car manufacturer. The telltale signs of a problem include:
- Misfiring of the engine, especially when accelerating or driving uphill.
- Difficulty starting the engine, especially in damp weather.
9 HT lead problems
This only applies to cars with a petrol engine. The HT leads connect the spark plugs to the coil, and they deteriorate with age. To help to avoid problems, keep the HT leads clean and make sure that they’re connected securely. The telltale signs of a problem include:
- Misfiring of the engine, especially when accelerating or driving uphill.
- Difficulty starting the engine, especially in damp weather.
10 Blown head gasket
A leaking cylinder head gasket can be a big problem, and major work on the engine may be required to fix it. There’s little that can be done to avoid this problem, but a major cause is engine overheating, so keep an eye on the temperature gauge from time to time, and if the temperature creeps towards the red zone stop immediately and check the coolant level. The telltale signs of a problem include:
- A lack of power.
- Misfiring, especially when the engine is cold or when starting.
- Fluid leaks on the outside of the engine.
- Oil in the coolant – usually shows itself as a frothy ‘mayonnaise’.
- Coolant in the oil – usually shows itself as a frothy ‘mayonnaise’.