How to change spark plugs: expert method and tips

change spark plugs

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Spark plugs require maximum performance: several thousand times per minute, they ignite the air-gasoline mixture in the gasoline engine. But how long do spark plugs they last? Our guide outlines when and how to change spark plugs.

When should you change spark plugs?

Modern spark plugs can travel between 30,000 and 60,000 kilometres, depending on the engine and manufacturer, before they have to be replaced. Iridium or platinum spark plugs allow even longer change cycles. But at some point every spark plug is used up.

Signs you need to change spark plugs: ignition stopsets and start-up problems,

Low-power, used spark plugs make themselves audible and noticeable: for example, by ignition stopovers, problems when starting the engine or by jerking while driving. Lower engine power and increased fuel consumption are therefore also typical warning signals.

Caution when changing spark plugs

Certainty comes with a visual inspection: spark plugs with worn electrodes that look burnt or charred should be replaced. Here, the spark can no longer skip properly and the engine can no longer work optimally. Untrained mechanics should leave the spark plug change to a specialist workshop. Amateurs can do a lot of damaging work and, for example, damage the thread when screwing in.

However, if you want to change the spark plugs yourself, it is not difficult if you approach the job carefully and do not try to force anything.

Step-by-step: How to change spark plugs

  • First, access to the spark plugs must be established. With older vehicles, this is easy, as you already have the spark plug plugs in front of you after opening the bonnet. In the case of newer cars, some cladding that hidesthe spark plugs must be dismantled first.
  • If you have access to the spark plugs, the spark plug plugsmust be removed. These are assigned to one cylinder each and must be reattached in the correct place even after the change
  • Now the upper part of the spark plug can be seen. Before unscrewing the spark plugs, however, it is recommended to clean the spark plug shaft with a hard brush. This ensures that no dirt enters the cylinders after turning out.
  • Next, unscrew the spark plug using the spark plug key. You should work carefully so as not to damage the thread in the cylinder head. If necessary, impurities in the thread can also be removed with the cloth.
  • Now the new spark plug can be screwed in manually. By screwingin by hand, you can better determine whether the thread of the candle and cylinder head fits correctly.
  • As soon as the spark plug sits securely in the thread, you can tighten it with the torque wrench and the corresponding tightening torque.
  • Finally, only the candle plugs have to be plugged into the upper halves of the spark plugs.
change spark plugs

Changing spark plugs: The right tool

You need the right tool to replace the spark plugs. On the one hand, you need a special spark plug key,which is available from specialist car dealerships. Since this key is available in different versions, you must first determine which one fits your vehicle. As an alternative, you can also use so-called spark plug nuts. These are plug-in bowls with special spark plug inserts that hold the candle after turning it out. Since the spark plugs are often difficult to access, a ratchet extension is also necessary. Finally, you need a torque wrench,a large brush and a cleaned cloth. You can then use this accessory to replace it.

Watch out for these things

If you want to change the spark plug yourself, there are a few things to watch out for.

  • The spark plugs may only be changed when the engine is cooled, because both the spark plug and the cylinder head expand during heating. If the new, cold spark plug is screwed into the hot cylinder head, it can happen that it gets stuck there after cooling down.
  • In addition, the ignition of the car must be on display.
  • The mass pole of the battery must also be disconnected in advance.

Act in time for defective plugs

It is particularly important to detect defective spark plugs at an early stage. These usually become noticeable after a short time. For example, if there are ignition stopters or if the full engine power is no longer available, the reason for this may be a defective spark plug. Then it is high time to visit a specialist workshop – or to replace the spark plugs yourself using this manual.

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