How is a spark plug constructed and what must be taken into account when replacing it? Spark plugs are the heart of every internal combustion engine that runs on gasoline. They have to be one high thermal load withstand and ensure a steady and powerful ignition spark so that the start of the engine, its full performance and low pollutant emissions can be guaranteed. That is why it is important that the right spark plugs to be chosen. How a spark plug is constructed and how you get one Defekt find out in this article.
Basic information about spark plugs
The function of a spark plug is very important for gasoline engines because they ensure that the Gasoline-air mixture ignitesto operate the pistons or the engine. A gasoline engine can function properly without spark plugs cannot can be guaranteed, as this can neither be started nor operated. The different models of spark plugs differ in the Diameter of the thread, im Heat value and in electrode distance. Particular attention should be paid to these values when buying.
Depending on the speed behavior of the engine, the spark plugs must be up to 5000 times per minute give a spark to the engine and function consistently regardless of the temperature. Since both the thermal load and the pressure differences are very high, a regular exchange or maintenance is important for the function of the engine.
The structure of a spark plug
At the top of the spark plug is the spark plug. Here the required voltage is generated via the thick cable. On the other side of the spark plug, the so-called Arcing instead of. The center electrode passes the generated current on to the ground electrode so that the mixture can be ignited in the combustion chamber.
The housing of a spark plug consists partly of a thread that is screwed towards the cylinder. The other part consists of Ceramics and serves as an insulator to ensure a permanent current flow through the center electrode. The required voltage is provided by the ignition coil generated. From there, the current flows to the center electrode with the help of the ignition cable between center and ground electrode a spark can be generated.
What does the heat value for spark plugs mean?
The heat value of a spark plug indicates its temperature behavior. It is between warm and cold spark plugs differentiated. If a too cold spark plug is installed in an engine, the required one can be used Working temperature of 500 - 900 degrees Celsius cannot be achieved. This leads to soot deposits in the electrodes and the required ignition energy cannot be generated.
If a too warm spark plug has been installed, in the worst case it can lead to one Glow ignition cause damage to the pistons and valves. Simply put: The higher the operating temperature of an engine, the colder must be the spark plug. If the temperature generated by the engine is lower, a warmer spark plug must be installed. at tuned vehicles, which are often driven more sportily and therefore often reach a higher operating temperature, can be a colder spark plug to improve.
Features of a damaged spark plug?
To diagnose a defective spark plug should be on different ones optical features respectively Spark plug faces be respected. The different characteristics describe different problems and can be broken down as follows.
A worn spark plug: A worn spark plug can either go through burned down Center electrodes and / or ground electrodes come about. The wrong fuel, unsuitable engine oil or an incorrectly selected spark plug can be considered. It should be checked whether the engine needs a warm or a cold spark plug and which one is currently installed.
A burned out spark plug: The reasons for this can also be the wrong fuel or an unsuitable engine oil for the engine. If the situation arises where a lot of engine oil is burned, we recommend that you visit a workshop so that the cause can be found and rectified.
An oily spark plug: If the spark plug is very oily, this is usually an indication defective piston rings there. Another possible cause is an insufficiently tight spark plug.
A charred spark plug: If the spark plug is charred, it usually shows too high Temperatures in the engine. Again, an excessively rich gasoline-air mixture or an incorrect heat value of the spark plug come into question. Vehicles with chip tuning often tend to have a rich mixture. In such cases, the software should be checked again and revised.
A white or gray discolored spark plug: If the spark plug with white or gray If deposits are covered, this indicates problems similar to those of a coked spark plug. This is because deposits of this type also arise at temperatures that are too high.
The center electrode of the spark plug can no longer be seen: If the center electrode is burnt or no longer visible, you can wrong timing be responsible for it. These can be adjusted if the toothed belt is overstretched. In addition, an incorrect heat value can also be responsible for this.
The contact between the two electrodes is poor: If the engine is mainly used for short journeys, deposits can form between the electrodes. As a result, the distance becomes smaller and in the worst case no contact is formed at all, which is necessary for the ignition.
What do you have to pay attention to when changing the spark plugs? Example Audi A3 8P!
If one or more spark plugs are defective, they can also be changed independently. For this only one spark plug wrench and needs some technical understanding. In order to be able to reach the spark plug, the spark plug connector must first be removed. This is located on the other side of the ignition cable that runs towards the engine. The ignition cables can be pulled off with a little effort and the spark plugs can then be dismantled. Care must be taken to ensure proper pressure when installing new spark plugs. Best will be a torque wrench used. And spark plugs always will clockwise attached. You can determine how exactly the process is when switching HERE .
Manufacturer, cost and face value: these should be taken into account when buying
Since not every spark plug is simply compatible with every engine, should Denominations and Codes be known in advance. An incorrectly installed spark plug can otherwise cause improper ignition or further damage to the engine. Well-known manufacturers of spark plugs are for example NGK or BOSCH. In terms of costs, both are almost identical and offer entire sets with multiple spark plugs for many vehicles.
Frequently asked questions about spark plugs for cars
How do you recognize a defective spark plug?
- Typical symptoms of a defective spark plug are often one uneven engine idling or difficulty starting the engine. Often there is also reduced engine performance or misfires when accelerating.
What does a new spark plug cost?
- Spark plugs from well-known manufacturers cost between 3 - 10 EUR. Sets with several spark plugs are also available. Such sets are recommended because most of the time all spark plugs are changed at once. When replacing it by a workshop, it becomes more expensive, since the labor costs for the change are still incurred.
How long do NGK spark plugs last?
- Spark plugs of the LaserLine variant from NGK last 60.000 kilometers. This is significantly longer than with previous spark plugs.
Which spark plug will last the longest?
- Spark plugs have the longest service life platinum. For this reason, many automobile manufacturers use them, as the service life is around 60.000 kilometers.
Can you change spark plugs yourself?
- If the right spark plugs and a spark plug wrench are available, they can be done quickly and easily be exchanged yourself.
When should spark plugs be replaced?
- The spark plugs must be changed depending on the type of vehicle and the annual mileage between 30.000 and 60.000 kilometers to recommend.
Do diesel engines also have spark plugs?
- Because diesel engines Compression ignition there is no need for spark plugs. To operate diesel engines, one uses so-called glow plugswhich are only responsible for starting the engine from cold.
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