How to Change Spark Plugs and Wires in 5 Easy Steps

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Engine DIY
Spark Plug Wires

Regular maintenance could mean the difference between having a car that lasts for just 80,000 km or up to 800,000 km. The brand of the car has a lot to do with it, too, and some like Toyota and Honda are known for their reliability and longevity. As a Do-It-Yourselfer, even with just basic mechanical knowledge and a manual, there are a few things that you can do to maintain your vehicle without spending a lot at the service department. These even applies with learning how to change spark plugs and wires.

How to Change Spark Plugs and Wires

Without a good spark, your engine won’t run well, or at all, depending on how bad the wear is. Some older vehicles require spark plug replacement every 80,000 km, but some new engines are equipped with plugs that last over 160,000 km. Whatever your vehicle requires, stick with the manufacturer’s specification spark plug. Installing a different type may work for a little while, but could get fouled up and fail after just a short time.

For this job you’ll need:

  • Complete set of new spark plugs (never replace just one or two)
  • Anti-seize lubricant
  • Special spark plug socket
  • Spark plug gap tool
  • New set of spark plug wires
  • Needlenose pliers

Spark plugs are fairly basic, they have an insulator and a threaded part with two electrodes. There are various designs, but the principle is the same. Be careful not to drop a spark plug, as this can bend the electrode and ruin the gap, the distance between the two electrodes. A spark plug gap tool both measures and adjusts the gap if necessary, and this information can often be found on a sticker under the hood or on the engine, or in the manual.

Spark Plug 4

Spark Plug Gap Tool

1. Apply anti-seize lubricant to spark plug threads

Spark Plug 1

Use a small amount of anti-seize lubricant on the threads only, and turn the spark plug by hand into the hole until it stops.

2. Install the new spark plug

Spark Plug 2

Use the ratchet and turn the spark plug ¼-turn or 90° if it has a washer. Washerless spark plugs get turned ⅛ or 45° for proper sealing.

3. Replace the spark plug wire to the newly installed spark plug

Spark Plug 3

Install the new rotor and cap and then work on the wires, one at a time. Factory wires should be numbered, making installation very easy. If you’re using generic wires, you may have to match up the length of the wire, starting with the shortest. If you break one of the old wires, you may need a pair of needlenose pliers to pull what’s left of the spark plug wire off the spark plug. Also, if you weren’t planning on replacing spark plug wires, but one breaks during the repair, it’s time for new wires.

4. Repeat Steps 2 and 3 for remaining spark plugs and wires

To reduce any confusion or potentially cross spark plug wires, a best practice is do steps 2 and 3 in pairs.

5. Check that the intallation is working

Start the vehicle. If the engine runs rough, go back and check your work, perhaps you left a coil unplugged or swapped two spark plug wires. Some engines, like V6 and V8 engines, will have two banks of spark plugs, which is only slightly more complicated when it comes to keeping track of spark plug wires. Some V6 engines may also be mounted sideways in the engine bay, which makes accessing some spark plugs difficult.

The video below offers a simple explanation to changing spark plugs and wires in a Dodge Caravan.

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