How to Replace Spark Plugs in Your Car

Save big on car maintenance costs by changing spark plugs yourself!

Time

A few hours

Complexity

Beginner

Cost

$20-50

Introduction

Changing spark plugs takes almost an hour (for a four-cylinder engine) and volition save you at least a hundred bucks in labor if you exercise it yourself. In about cases it'southward a simple job that will assistance to maintain peak performance and the highest possible gas mileage.

Tools Required

Materials Required

  • Anti-seize compound
  • Dielectric grease
  • Spark plugs

Project step-by-step (7)

Step 1

Why Do Spark Plugs Need to Be Changed?

When a spark jumps the gap betwixt 2 electrodes, it really burns off (erodes) minor amounts of metal from each 1. Over time, the gap grows to the point where the spark can no longer make the jump. That's when you get misfires, lower gas mileage, poor acceleration and, ultimately, the dreaded "Check Engine" light.

When to Check & Modify a Spark Plug

Not all spark plugs are rated for 100,000 miles. In fact, some carmakers recommend replacement at thirty,000-mile intervals. Always follow the spark plug service intervals shown in your owner's manual to figure out when to replace spark plugs. But if y'all can't recall when y'all concluding changed your spark plugs, y'all can pull them and check the gap and their condition. Once you've put in the labor to begin checking spark plugs, nonetheless, you might too change them and found a new baseline for the futurity.

Bank check out our favorite machine diagnostic tools for DIYers here.

Signs of a Bad Spark Plug

Unlike manufacturers' guidelines for oil changes, which are overly cautious, the recommendations for how often to change spark plugs tend to be overly optimistic.

For instance, if you've already got 80,000 miles on a gear up of 100,000-mile plugs, they're 80 per centum worn and beginning to take a cost on engine performance and gas mileage. Worse notwithstanding, later on that many miles there is enough of spark plug wear, and spark plugs tend to seize in the cylinder head.

Removing a seized plug can be plush, specially if the threads in the cylinder caput are damaged. So what are the benefits of changing spark plugs? When yous consider the gas mileage falloff and the possibility of seized plugs, early on replacement makes sense.

Do it Yourself or Take it to a Pro?

The answer depends on the type of engine in your vehicle. Some V-6 models require removing portions of the intake manifold to replace the spark plugs. If you're not comfortable with that, have your vehicle to a pro. But if your engine affords easy access to the rear bank, you can probably practise the job yourself. Simply be sure you lot gap the spark plugs properly and use a torque wrench.

The tools shown are available at online suppliers and car parts stores. While you're there, ask the clerk for the spark plug gap and torque specifications for your vehicle. And buy a small packet of dielectric grease. It'south besides important to inquire about spark plug replacement toll earlier making an appointment.

Pace two

Open up Upward and Clean Your Work Area

Start by removing the plastic "vanity" cover (if equipped) and the air cleaner associates from the top of the engine.

  • Label any vacuum hoses yous remove so yous restore them to the correct identify.
    • Pro tip: Acquire the top of a 4-cylinder engine, or the banks on a "V" engine, before yous remove other parts.
  • Blast compressed air around the ignition coils to preclude crud from falling into the cylinders. And then blow any remaining loose dirt off the engine earlier you set out your tools and new plugs.

change spark plugs

Step 3

Remove the Ignition Coil and/or Kick

  • Disconnect the ignition coil electrical connector by depressing (or pulling up) on the locking tab.
  • Rock the connector off the ringlet.
  • Remove the ringlet agree-down commodities and pull out the entire coil and kick assembly.
    • Pro tip: Some COP systems accept a detachable rubber kick and leap. If they don't come out with the curl, remember them with needle-nose pliers and supplant them with new parts. And so remove the old spark plug.

If your auto doesn't accept COP ignition, the spark plug wire will terminate in a boot that attaches to the spark plug. A spark plug wire puller makes it easy to pull the kick off.

change spark plugs

change spark plugs

Step 4

Unscrew the Plug

  • Accident away the dirt and crud that's settled on and effectually the plug since information technology was installed.
  • Slide the proper size spark plug socket over the plug.
    • Pro tip: A swivel caput spark plug socket makes the job much easier. You'll probably need an extension of some length to attain the plug.
  • Rotate the plug counter-clockwise to loosen it.
    • Pro tip: Not all engines get out the plugs as accessible as shown here. The more compact the engine compartment, the harder it will be to get to the plugs. Only all plugs tin exist removed.

change spark plugs

Step 5

How To Gap a Spark Plug

Gap all plugs before installation using the manufacturer's specs. Ever cheque the spark plug gap before installing information technology.

  • Slide the right wire gauge (or gap judge) between the electrodes. The wire should drag slightly between them.
  • If the gap is too minor, open it with the gap estimate by prying up.
  • If the gap is too large, tap the side electrode lightly on a solid surface.
  • Place a small dab of anti-seize compound on the plug threads and hand thread the plug into the cylinder caput.

change spark plugs

Stride 6

Install the New Plug

Proper spark plug torque is disquisitional in today'southward engines.

  • Always use a torque wrench and the manufacturer's spark plug torque specs. Insufficient torque tin result in a plug bravado right out of the cylinder head, taking the threads with it. Too much torque distorts the plug.
  • If y'all used anti-seize compound on the plug threads, reduce torque by 10 percent. If you lot don't take a torque wrench, go to the spark plug manufacturer's website to find transmission tightening techniques and spark plug torque specs.

change spark plugs

Footstep vii

Lube the Spark Plug Kick and Button It Up

  • Apply a thin coating of dielectric grease around the inside of the spark plug boot earlier reinstalling the curlicue. The grease prevents misfires and makes it easier to remove the kicking in the future.
  • Reinstall the ignition coil, concur-down commodities and coil electrical connector.
  • Reinstall the air cleaner and vanity comprehend and burn down it upward.

Note: Follow the same procedure for non-COP ignition system boots.

change spark plugs