Spark plugs are responsible for delivering electricity from your ignition to your engine. Good spark plugs ensure a smooth start each time you turn on your car. If your vehicle is struggling to start when you turn the key in the ignition or your check engine light appears on the dashboard, it may be time for a replacement. This guide will explain the basics of how to change spark plugs.
When to Check & Change a Spark Plug?
Not all spark plugs are rated for 100,000 miles. Some carmakers recommend replacement at 30,000-mile intervals.
So, how often should you change your spark plugs? That depends on a variety of factors, including the type of spark plugs your vehicle uses:
- Ordinary copper and nickel spark plugs should be changed every 30,000 to 50,000 miles unless otherwise suggested by the spark plug manufacturer.
- Platinum and iridium spark plugs tend to last longer than standard copper and nickel spark plugs. Expect to change them every 60,000 to 150,000 miles unless otherwise noted.
Other factors that could affect your vehicle’s spark plug replacement interval include how you use your vehicle. If you subject your vehicle to high-performance driving regularly, for example, you may need to change your spark plugs more often. Constant idling, frequent towing, and driving in severe heat or cold weather conditions may increase how often you’ll need to replace your spark plugs.
The easiest way to find out how often you’ll have to replace your spark plugs is simply by following your vehicle owner’s manual. It’ll have all the information you’ll need to ensure your vehicle receives timely care.
But if you can’t remember when you last changed your spark plugs, you can pull them and check the gap and their condition. Once you’ve put in the labor to begin checking spark plugs, however, you might as well change them and establish a new baseline for the future.
How Long Does It Take to Change Spark Plugs and Wires?
On average, the amount of time it takes to replace spark plugs on a vehicle is around 1-2 hours. However, depending on experience and speed, it could take a beginner a bit longer to fully complete the job. In any case, it’s important to approach each step carefully and make sure you have the right tools and equipment nearby to get the job done.
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How To Change Spark Plugs?
1. Safety First.
Park your vehicle on a flat, dry surface and ensure the engine is cool. Clean the engine area of any dirt and debris to prevent anything from falling into the engine cylinder during spark plug replacement.
Additionally, you may want to disconnect the battery (negative post only). Check the vehicle repair guide or other resources to ensure no damage will occur if the battery is disconnected for any length of time or if any modules or other items would need to be reprogrammed.
Ensure the positive and negative terminals do not become crossed with a foreign object such as a hand ratchet and cause a dangerous short circuit.
2. Disconnect the Spark Plug Wire or Coil-On-Plug Connectors
First, remove any interference items and disconnect the wires from the spark plugs. You can use your owner’s manual as a guide to locate the spark plugs if necessary.
Spark plug wires are removed with a simple straight-up pulling motion, holding on to the boot that slips over the plug itself. Remember to label each wire to keep them in the correct order for reinstallation.
Coil-on-plug connectors often feature a locking tab that you may have to depress with a screwdriver to release before you’re able to pull the connectors off—be sure to label them carefully for reinstallation. Once disconnected, carefully inspect the plugs, and wipe clean.
3. Remove the Old Spark Plugs
Use a spark plug socket paired with a 3/8 ratchet to loosen and pull the first plug from its housing. These sockets are designed to securely grip the spark plugs for effortless removal and may require a socket adapter to use with your current drive tool.
Discard the old plugs after inspecting them for corrosion and confirming they need to be replaced.
4. Prep the new spark plugs
Before installing the new spark plugs, ensure each plug part number matches the part number and box description. Inspect each new spark plug for damage.
Ensure the threads are clean and straight, the electrode and tip are intact, and the insulator for the plug wire or COP boot is not cracked or chipped. Some brands of spark plugs come ‘pre-gapped’ and require no ‘re-gapping’.
For these spark plugs, make sure the tip is not bent or damaged. For other brands and plug types, check the gap to make sure it matches your engine’s plug gap specification.
Read More: How to Gap Spark Plugs?
5. Install New Spark Plug
Make sure the cylinder head is cool to the touch and begin by hand-tightening the plug to reduce the risk of damage.
Use a torque wrench to finish installing the new spark plugs. Check the instructions included with the new spark plugs to confirm the correct torque specifications.
6. Reattach Wires/Coil-On-Plug Connectors/Battery
Apply a thin coating of dielectric grease around the inside of the spark plug boot before reinstalling the coil. The grease prevents misfires and makes it easier to remove the boot in the future.
Wrap up your installation by reinstalling the vehicle’s spark plug wires or coil-on plug connectors in the correct order, and then reconnect the battery.