How to Replace Spark Plugs in Your Car

Salve big on car maintenance costs past changing spark plugs yourself!

Fourth dimension

A few hours

Complication

Beginner

Price

$20-50

Introduction

Changing spark plugs takes most an hour (for a four-cylinder engine) and will save y'all at to the lowest degree a hundred bucks in labor if you lot do it yourself. In most cases information technology's a elementary task that will assistance to maintain summit performance and the highest possible gas mileage.

Tools Required

Materials Required

  • Anti-seize compound
  • Dielectric grease
  • Spark plugs

Project pace-by-footstep (7)

Footstep 1

Why Do Spark Plugs Need to Be Changed?

When a spark jumps the gap between two electrodes, it actually burns off (erodes) small amounts of metal from each one. Over time, the gap grows to the bespeak where the spark tin can no longer make the spring. That'southward when you lot get misfires, lower gas mileage, poor acceleration and, ultimately, the dreaded "Check Engine" lite.

When to Check & Change a Spark Plug

Not all spark plugs are rated for 100,000 miles. In fact, some carmakers recommend replacement at 30,000-mile intervals. Always follow the spark plug service intervals shown in your owner's manual to effigy out when to replace spark plugs. But if you can't remember when you last changed your spark plugs, you can pull them and bank check the gap and their condition. Once you've put in the labor to begin checking spark plugs, withal, you might too change them and establish a new baseline for the future.

Check out our favorite car 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 frequently to change spark plugs tend to be overly optimistic.

For example, if you've already got lxxx,000 miles on a set of 100,000-mile plugs, they're 80 percent worn and start to take a toll on engine operation and gas mileage. Worse even so, after that many miles there is enough of spark plug wear, and spark plugs tend to seize in the cylinder caput.

Removing a seized plug can be costly, especially if the threads in the cylinder head are damaged. And then what are the benefits of changing spark plugs? When you consider the gas mileage falloff and the possibility of seized plugs, early replacement makes sense.

Do it Yourself or Accept it to a Pro?

The answer depends on the blazon of engine in your vehicle. Some 5-six models require removing portions of the intake manifold to supercede the spark plugs. If you're not comfortable with that, take your vehicle to a pro. But if your engine affords piece of cake access to the rear bank, you can probably do the job yourself. Merely be sure you gap the spark plugs properly and use a torque wrench.

The tools shown are bachelor at online suppliers and auto parts stores. While y'all're at that place, ask the clerk for the spark plug gap and torque specifications for your vehicle. And buy a minor parcel of dielectric grease. It'due south too of import to ask about spark plug replacement toll before making an engagement.

Step 2

Open Upwards and Clean Your Piece of work Expanse

Start by removing the plastic "vanity" encompass (if equipped) and the air cleaner assembly from the height of the engine.

  • Characterization any vacuum hoses yous remove and so you restore them to the right place.
    • Pro tip: Learn the top of a 4-cylinder engine, or the banks on a "V" engine, before y'all remove other parts.
  • Blast compressed air around the ignition coils to prevent crud from falling into the cylinders. Then accident whatever remaining loose clay off the engine before yous set out your tools and new plugs.

change spark plugs

Step 3

Remove the Ignition Curlicue and/or Kicking

  • Disconnect the ignition whorl electrical connector past depressing (or pulling up) on the locking tab.
  • Rock the connector off the coil.
  • Remove the coil concord-downwardly bolt and pull out the entire scroll and boot assembly.
    • Pro tip: Some COP systems take a detachable rubber boot and jump. If they don't come out with the whorl, retrieve them with needle-nose pliers and supersede them with new parts. Then remove the sometime spark plug.

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

change spark plugs

change spark plugs

Footstep 4

Unscrew the Plug

  • Blow away the clay and grime that'due south settled on and around the plug since it was installed.
  • Slide the proper size spark plug socket over the plug.
    • Pro tip: A swivel head spark plug socket makes the task much easier. You'll probably need an extension of some length to reach the plug.
  • Rotate the plug counter-clockwise to loosen it.
    • Pro tip: Non all engines go out the plugs as accessible as shown here. The more compact the engine compartment, the harder it will be to become to the plugs. But all plugs tin can be removed.

change spark plugs

Pace 5

How To Gap a Spark Plug

Gap all plugs before installation using the manufacturer'south specs. Always check the spark plug gap earlier installing it.

  • Slide the right wire gauge (or gap gauge) between the electrodes. The wire should elevate slightly between them.
  • If the gap is too small, open information technology with the gap estimate by prying upwardly.
  • If the gap is too big, tap the side electrode lightly on a solid surface.
  • Place a small dab of anti-seize chemical compound on the plug threads and hand thread the plug into the cylinder head.

change spark plugs

Step 6

Install the New Plug

Proper spark plug torque is critical in today's engines.

  • Always use a torque wrench and the manufacturer's spark plug torque specs. Insufficient torque can consequence in a plug bravado right out of the cylinder head, taking the threads with it. As well much torque distorts the plug.
  • If you lot used anti-seize chemical compound on the plug threads, reduce torque by 10 pct. If you don't accept a torque wrench, go to the spark plug manufacturer's website to find manual tightening techniques and spark plug torque specs.

change spark plugs

Step seven

Lube the Spark Plug Boot and Button Information technology Up

  • Utilize a thin coating of dielectric grease around the within of the spark plug boot before reinstalling the curl. The grease prevents misfires and makes it easier to remove the boot in the future.
  • Reinstall the ignition scroll, hold-downwards bolt and coil electrical connector.
  • Reinstall the air cleaner and vanity embrace and fire it up.

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

change spark plugs

Originally Published: February 14, 2019