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

Price

$20-50

Introduction

Changing spark plugs takes virtually an 60 minutes (for a four-cylinder engine) and will save yous at least a hundred bucks in labor if you exercise it yourself. In most cases information technology's a unproblematic job that will help 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)

Footstep one

Why Exercise Spark Plugs Need to Be Changed?

When a spark jumps the gap between two electrodes, it actually burns off (erodes) modest amounts of metallic from each ane. Over time, the gap grows to the point where the spark can no longer brand the jump. That's when you become misfires, lower gas mileage, poor dispatch and, ultimately, the dreaded "Check Engine" calorie-free.

When to Cheque & Alter 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 transmission to figure out when to replace spark plugs. But if you can't recall when you concluding changed your spark plugs, you can pull them and check the gap and their status. In one case yous've put in the labor to brainstorm checking spark plugs, even so, you might equally well modify them and establish a new baseline for the futurity.

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 oft to change spark plugs tend to be overly optimistic.

For example, if yous've already got 80,000 miles on a set of 100,000-mile plugs, they're 80 percent worn and outset to have a toll on engine operation and gas mileage. Worse nevertheless, later on that many miles at that place is plenty of spark plug wear, and spark plugs tend to seize in the cylinder head.

Removing a seized plug tin be costly, especially if the threads in the cylinder head are damaged. So 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 Have it to a Pro?

The answer depends on the type of engine in your vehicle. Some V-half-dozen models crave removing portions of the intake manifold to replace the spark plugs. If you're non comfortable with that, have your vehicle to a pro. But if your engine affords piece of cake access to the rear banking company, you can probably exercise the job yourself. Just be sure you gap the spark plugs properly and use a torque wrench.

The tools shown are available at online suppliers and auto parts stores. While you're in that location, inquire the clerk for the spark plug gap and torque specifications for your vehicle. And buy a small bundle of dielectric grease. Information technology's also important to ask nigh spark plug replacement cost before making an engagement.

Step 2

Open Upwardly and Clean Your Work Area

Start past removing the plastic "vanity" cover (if equipped) and the air cleaner assembly from the summit of the engine.

  • Label any vacuum hoses you lot remove so y'all restore them to the right identify.
    • Pro tip: Learn the top of a four-cylinder engine, or the banks on a "V" engine, before you lot remove other parts.
  • Blast compressed air around the ignition coils to foreclose grime 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

Footstep iii

Remove the Ignition Coil and/or Boot

  • Disconnect the ignition coil electric connector by depressing (or pulling up) on the locking tab.
  • Rock the connector off the scroll.
  • Remove the coil hold-down bolt and pull out the entire scroll and kicking assembly.
    • Pro tip: Some COP systems have a detachable safe kick and bound. If they don't come out with the roll, recall them with needle-olfactory organ pliers and supervene upon them with new parts. Then remove the old spark plug.

If your car doesn't take COP ignition, the spark plug wire will cease in a boot that attaches to the spark plug. A spark plug wire puller makes it piece of cake to pull the boot off.

change spark plugs

change spark plugs

Step iv

Unscrew the Plug

  • Accident away the dirt and grime that's 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 job 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: Not all engines leave the plugs as accessible as shown here. The more compact the engine compartment, the harder it will be to get to the plugs. But all plugs can be removed.

change spark plugs

Step v

How To Gap a Spark Plug

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

  • Slide the correct wire gauge (or gap guess) between the electrodes. The wire should drag slightly betwixt them.
  • If the gap is as well small, open information technology with the gap gauge by prying upwardly.
  • 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

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 effect in a plug blowing right out of the cylinder head, taking the threads with it. Too much torque distorts the plug.
  • If yous 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

Pace seven

Lube the Spark Plug Kick and Button It Upwardly

  • Employ a sparse 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.
  • Reinstall the ignition curlicue, hold-down commodities and coil electrical connector.
  • Reinstall the air cleaner and vanity cover and fire it up.

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

change spark plugs

Originally Published: February 14, 2019