I am a husband, father, and writer with an interest in DIY auto repair.
This is a guide to changing the spark plugs on a 4-cylinder 2006 Kia Optima. Although the Kia Optima is in its third generation, the first two generations have not changed the spark plug locations at all, meaning that this how-to should be fairly accurate in all models from 2000 until 2010.
The Tools for the Job
- 10 MM Combination Wrench
- 3/8 Inch Drive Ratchet
- 6 Inch 3/8 Inch Drive Extension Bar for the Ratchet
- 5/8 Inch 3/8 Inch Drive Spark Plug Socket (spark plug sockets are different from deep well sockets. Spark plug sockets have thinner walls and a rubber washer inside.)
- 13/16 Inch 3/8 Inch Drive Spark Plug Socket (spark plug sockets are different from deep well sockets. Spark plug sockets have thinner walls and a rubber washer inside.)
- 10 MM Socket (If you have a 3/8 drive 10 MM socket then great. Most sockets of this size are 1/4 inch drive and requires the adapter to 3/8 inch drive. This is in the picture.)
- Spark Plug Gap Gauge
You may be wondering why you need two different size spark plug sockets. I have the answer for you! If your vehicle has just passed 100,000 miles then your spark plugs have probably never been replaced. The original spark plug will require the 13/16 inch socket and the replacement spark plug will require the 5/8 inch socket. I guess that is one of those things all of us shade-tree mechanics use to accuse tool makers and car dealers of being in cahoots together!
A Few "Before You Start" Pointers
Which Replacement Spark Plug Do I Buy?
When you roll into your neighborhood auto parts store, they will give you multiples choices of spark plugs to purchase. The price can range from $2 a piece up to $16 a piece. The sales staff will typically sell you on the more expensive brand in order to improve fuel economy and performance. If you are a performance junkie or your commutes are extremely long, then the more expensive spark plugs may interest you. I recommend you go with the manufacturer's recommendation. In this case you will need to purchase a Double Platinum spark plug. You can find these for approximately $3 to $5 a piece.
Before you pop the hood and get started on replacing the spark plugs, make sure the motor is cool. If at all possible, perform the replacement the morning after the vehicle has been sitting all night. When doing the repairs in the summer, you might want to find a place to park the car in the shade the night before. This will truly make you a shad-tree mechanic.
Also, remember that you should not place ANY tools on or around the battery. Just one tool touching the positive and negative connection on the battery can be very dangerous. Safety first!
One last pointer, check with your doctor to make sure you are healthy enough for vehicle repairs. You will need to bend over for long periods of time, be able to handle the environmental elements and be healthy enough to put significant pressure on the tools while loosening or tightening parts.
Pop the Hood
First, and this is obvious, pop the hood. Under the left hand side of the steering column, you will see a lever to "pop" the hood. Once this is accomplished, release the lever under the grill on the driver's side of the car (close to the Kia emblem). Lift the hood all the way open.
Disconnect the Battery
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As I said before, safety first and foremost. Disconnect the positive battery cable. The positive cable should be on your left side but check the battery first. The battery will be clearly marked positive and negative. Grab your 10 MM combination wrench and loosen the bolt on the battery cable that releases the pressure on the battery post. Once the cable is loosened, move it away from the battery to ensure the cable does not accidentally touch the battery post.
Remove the Cover
Now you will need to remove the four 10 MM bolts attaching the cover that is over the spark plug wires and coils. For this you will use the ratchet and the 10 MM socket. Once you have removed the first bolt, place the bolt in a labeled container so that you know where the bolts go back. I realize that this is a minor repair and that the few bolts you will be removing during this repair are easily replaced. I suggest the labeled container as a habit so that you will not lose bolts and nuts during more complicated repairs and maintenance. I save canned good cans for this purpose but you use whatever "flips your skirt up." Once all four bolts are removed and placed in your labeled container, simply lift up on the cover and place the cover aside.
With the cover off, you will see a spark plug wire, a coil, a spark plug wire, a coil and then a spark plug wire. First pull up on the first spark plug wire. You should feel a very slight pop when you remove the wire. Grab the 13/16 inch spark plug socket and the 6 inch extension bar and snap them together. Place the attached spark plug socket into the hole where you see the spark plug at the very bottom. Push the socket onto the spark plug, allowing the rubber washer to fit firmly. Attach the ratchet and loosen the spark plug. After a few turns, it may be easier to remove the ratchet and turn the extension bar by hand. Once the spark plug is loosened, it will be attached to the socket washer and should come out with the socket. Be very careful not to allow debris to fall into the hole where the spark plug came out of.
Get a new spark plug and the spark plug gapping tool. The gap should be the same on all 4 spark plugs. The suggested gap measurement should be between .039 to .043. Once properly gapped, remove the 13/16 spark plug socket and attach the 5/8 spark plug socket to the extension bar. Insert the new spark plug into the socket firmly so that the spark plug does not fall out of the socket. Insert the socket into the hole where you removed the old spark plug. Tighten the new spark plug into place. The spark plug should be tightened firmly but do not over tighten! Attach the removed spark plug wire. Make sure the wire is pushed all the way down.
Now move onto the spark plug under the coil. There will be two 10 MM bolts to loosen the coil. You will be using the 10 MM socket again to remove these bolts. Once they are loosened, place them in a different container. Pull straight up on the coil. Repeat the procedure to remove the spark plug and insert the new spark plug, as outlined previously. Place the coil down into the hole where the new spark plug was inserted. Replace the two bolts previously removed from the coil.
Remove the next spark plug wire and repeat the process of removing and replacing the spark plug. Push the spark plug wire back into place. Remove the last coil, according to the previously stated directions. Remove and replace the spark plug. Return the coil back to the hole with the new spark plug. Replace the bolts attaching the coil.
Return the Cover and Reconnect the Battery
Now that the spark plugs have been replaced, reattach the cover. A tip first, whenever replacing two or more bolts on one piece you do not want to just go around in a circle. Start with the left top bolt tightening it only hand tight. Then go to the bottom right corner tightening it only hand tight. Proceed to the bottom left and then the top right, tightening each bolt only hand tight. Now use the ratchet and, in the same order, tighten each bolt. Finally, start with the top left bolt and proceed in a circle to make sure all bolts are tightened.
Reconnect the battery cable to the battery post and tighten the 10 MM bolt with the combination wrench. Before you close the hood and start up your vehicle, check to make sure you have removed all your tools from the engine and surrounding areas. The last thing you need is a wrench in the alternator belt!
Start your vehicle and be proud of a job well done!
Replacing the Spark Plugs
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.