Check and replace spark plugs

The engine in the car is used to create torque, which will allow the wheels to rotate. But the engine can work both on gasoline and on diesel or, in general, on gas. If in diesel engines the ignition occurs due to the compression of the fuel to enormous pressure, then the gasoline engines need a third-party source - the spark plug. And they often create problems, due to which engine start-up deteriorates, fuel consumption increases, power is lost. If not all, then much depends on their condition, therefore replacement of spark plugs should be done in a timely manner.


  • 1 Types of Spark Plugs
  • 2 How to determine the malfunction of the spark plug
  • 3 How to check spark plugs
  • 4 How often to change candles
  • 5 How to replace the candles
  • 6 Diagnosing engine condition by spark

Spark Plug Types

what is the spark plug

Spark Plug Device

On the order of 20-30 kV, it is necessary that the mixture of air and gasoline be ignited in the combustion chamber. A candle is a power element in which a high-voltage discharge takes place. In the design of the ignition system, of course, prior to the candle, voltage transducers and a distributor are installed, which supplies high voltage to the cylinders in a timely manner. A standard spark plug is a small device consisting of an all-metal body that is threaded to ground (minus), an electrode, and a ceramic insulator. A spark charge arises between the central electrode and the housing, exactly during the compression cycle in the cylinder (provided that the ignition control is correct).

Diesel engines have a slightly different scheme of fuel ignition - diesel fuel starts to burn with a sharp compression. But in the cold season, even they use elements of heat, which increase the temperature in the cylinders, feeding them hot air during the formation of the mixture. Their work is somewhat similar to those used on gasoline engines. Disconnection of these elements occurs after the engine is warming up to a normal, operating temperature. But in gasoline engines, spark plugs play a much more significant role than the elements of the glow in diesel. All the main characteristics of gasoline engines depend on how high-quality elements in them are used and in what condition they are.

How to determine the malfunction of the spark plug

replace spark plugs

Cracks on the insulator candles - a sure sign of trouble

Signs indicating a poor state of candles, quite a lot. Here are the main ones:

  1. Starting the engine is difficult or, in general, impossible.
  2. Unsustainable speed, low acceleration, lack of traction, the engine troit.
  3. There is a loss of power.
  4. Increases fuel consumption.
  5. The level of carbon dioxide is above normal, the color of exhaust gases changes when the engine is fully heated.
See also: Classification of motor oils

But the same signs, unfortunately, are also present in case of violation of the mode of operation of the carburetor or injector, ignition system, piston group and valves. But the first thing is to check the candles, as they fail more often than the pistons.

How to check spark plugs

To determine whether the spark plug is suitable for use in a car engine, you just have to inspect it. No additional devices - only your eyes, capable of noticing even minor defects. A few signs that will tell you about the malfunction of the item:

spark plug replacement

Candles with damaged or melted electrode should be replaced immediately.

  1. The presence of soot or deposits of engine oil on the electrodes.
  2. Melting, deformation, damage to the electrodes.
  3. Cracks on the surface of the insulator.
  4. Damage to the thread or to the top of the central electrode.

Often a premature failure is due to the fact that the engine runs on poor quality fuel. Therefore, to increase the service life, it is necessary not only to maintain the vehicle’s ideal condition, but also to refuel it with high-quality gasoline. If during maintenance you suspect that the poor condition of the spark is caused by the use of low-grade fuel, change the filling station. Periodic inspection of the spark plugs will help you to avoid a sharp deterioration in engine performance, since when you inspect them you will be able to detect the problem in advance.

How often to change candles

Stable operation of the engine is directly dependent on the quality and timely maintenance. Carefully read the manual for your car, it indicates the frequency of replacement of spark plugs, and this value should be followed. But much depends on secondary factors - the quality of the spark plug, the fuel used, the operation of the injection and ignition systems. The average value is about 30 thousand km. run This is about a year away from the average motorist. But it is quite possible to increase the service life if the car system is maintained in perfect condition. And if you use platinum or iridium spark plugs, then they will have to be changed even less often, since their resource is much higher.

the frequency of replacement of spark plugs

On average, candles need to be changed every 30 thousand kilometers

How to replace the candles

Replacement is made on a cold engine. So you will protect yourself and the engine. When heated, the metal expands, because of this, the twisting of the element can be complicated. There is nothing difficult in the procedure, it is only necessary to have an allen key on 21 (on some cars it is necessary to unscrew it on 16). The procedure is as follows:

  1. Disconnect the high-voltage wire from the spark plug of the first cylinder. In order not to forget the location of the wires, change one by one.
  2. Before unscrewing, clean the engine surface around the element. It is better if it is carried out with the help of compressed air, but it is also possible with a paint brush.
  3. Unscrew the candle and instead install a new one.
  4. Put on the cap high-voltage wires.
  5. Replace others in the same way.
See also: Why the engine overheats

If access to the spark plugs is blocked by a plastic lining or a collector, then it is necessary to remove interfering elements for a while. After the replacement of the spark plugs, install the removed elements.

Diagnosing engine condition by spark

The appearance of the spark plug electrodes can tell a lot about the state of your engine. Even the slightest malfunction in the ignition system or fuel injection will affect the color of the electrode. In order not to spend money on expensive motor diagnostics services at a workshop, you can independently determine the condition of your car engine. Here are the main problems that can be diagnosed:

engine diagnostics by candlelight

Black bloom on the candles suggests that the engine is constantly enriched mixture

  1. If there is a black patina on the electrode, then this indicates that the engine is running on an enriched mixture, which means that there is a breakdown in the fuel injection system.
  2. But the light gray shade says about the poor mixture. The cause can be either an incorrectly set ignition advance angle or a breakdown in the cooling system.
  3. Pink bloom is a clear sign that it’s time to change a gas station, as you fill in low-quality gasoline that contains a lot of ethyl.
  4. The presence of engine oil indicates a poor tightness of either the unit or the head. This is usually observed with excessive wear of the piston oil seals or ceramic valve seals.
  5. But if you fill in low-octane fuel, then the central electrode and insulator will quickly collapse. Of course, if the spark plug has served twice as long as it should, similar defects may be present.

Если элемент полностью исправен, то у него будет светло-коричневый налет, никакого нагара и намека на масло. В противном случае необходимо replace spark plugs на вашем автомобиле. Что касается зазора между электродами, то корректировать его не нужно, в различных моделях свечей он колеблется в диапазоне 0,5-2 миллиметра. Если, конечно, есть необходимость, можно его изменить при помощи измерительных щупов.