How to Replace the Ignition Coil and Spark Plugs in an Older Car?

Sep 11, 2019

How to Replace the Ignition Coil and Spark Plugs in an Older Car?

The ignition coil is part of your car’s ignition system. How does it work? Well, it converts 12V battery power into high voltage, creating a spark at a spark plug. The spark ignites the air/fuel mixture in the engine cylinders.

Nowadays, it’s common for modern cars to have one ignition coil per cylinder. In other cars, ignition coils for all cylinders will be combined into one coil pack. In older cars with a distributor, a single coil will be used for all cylinders.

Ignition coil problems

You will be glad to know that ignition coil failures are common. Symptoms of a failing ignition coil include:

  • Engine shaking
  • Lack of power
  • Spluttering
  • Check Engine Light on the dashboard.

Cars that have a single ignition coil or a coil pack, will find that their car won’t start with a faulty ignition coil. Ignition coils are likely to fail if water enters the ignition bay, or if the spark plugs have not been replaced for a long time.

What you need replacement:

  • New ignition coils
  • Dielectric grease
  • Gloves
  • Repair manual
  • Ratchet and socket set
  • New spark plugs (if necessary)


Firstly, you need to remove the negative battery cable


Now you need to locate the coil packs or your ignition coil in your car’s engine bay. Cars with coil packs will generally have them mounted near a valve cover. Coil on plug ignition coils can be found near or directly over each spark plug. Be sure to remove any plastic engine covers to gain access to the coils.


Then, unplug the wiring harness. Do this by pushing the tab and pulling off the electrical connector.


Remove retaining bolts by holding your car’s coil in one place. Once this is unbolted, your coil pack can be removed. Some models may have locking tabs that need to be opened.


If it’s time to change the spark plugs, this is your chance to do so. If you have an older model of car we recommended replacing ignition coil and spark plugs at the same time.


Using the dielectric grease, apply to the end of the coil-on-plug style. Doing this prevents the boot from sticking to the spark plug and keeps water out.


You can now slide the new coil into place, pressing firmly to hear a click. Reattach the electrical connection and the coil pack retaining bolt.


If necessary, repeat this process until all units have been replaced. Then, reconnect the negative battery cable.

Not up to doing it yourself? Get a quote from our local mechanics!


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