Introduction
If you Google spark plug installation guide, you will find dozens of articles. However, from the few I looked at, they all missed some key parts. In this guide, the steps will be broken down as much as possible so that even if you have never worked on a vehicle, you can hopefully install spark plugs on your vehicle.
Some disclaimers before the guide gets underway. Some cars are v6, v8, or v10s, which may require removing an intake manifold to access the spark plugs. If this is the case replacing the spark plugs could be more difficult and my guide will only help so much. If the process seems too complicated it might be best to take the vehicle to a professional to have the spark plugs replaced. Furthermore, the vehicle I am demonstrating the replacement on is a coil-on plug style inline 4 cylinder.
Tools Required:
Sockets or Spark Plug Tool
Rachet to loosen and tighten the bolts.
Additional Tools:
Torque Wrench
Dielectric Grease
Penetrating Oil
Here are the steps to remove the plugs:
Step 1: Locate the hood release and release the hood latch. If done successfully there will be an audible noise as the hood is released.
Step 2: The picture shows what the hood latch looks like (Note: the hood latch is not visible while releasing the hood). The hood latch will be a lever that you need to pull or push on to access the engine.
Step 3: Locate the hood prop rod. The rod is either slightly behind the hood release or attached to the hood. Next, unclip the rod and place it where the hole is on either the car or the hood. My one car indicates where the rod should be placed but not all cars do.
Step 4: Disclaimer: with modern cars disconnecting the battery for long periods of time can be an issue. To be sure it is not an issue please refer to your vehicle’s owner manual to make sure it is safe to disconnect. If it is safe to disconnect the terminal go ahead and locate the battery and then the negative terminal. The negative terminal can be found by looking for the minus symbol on the battery. Once the negative terminal is found go ahead and loosen the bolt which will let the wire lift up off the post. Next, set the wire aside so that it will not have the chance to touch the post.
Step 5: Not all vehicles will have a vanity cover but if your vehicle does then the cover needs to be taken off. In most cases, the cover will slide and lift off. With vanity covers being plastic be extra careful not to damage it during removal.
Step 6: Locate the coil on plugs or spark plugs wires. The four coil-on plugs can be seen in the picture On v6 or v8 engines the engines are turned 90 degrees because of this the spark plugs are located on the left and right side of the engine.
Instead of coil-on plugs from the four spark plugs there could be spark plug wires. Here is what spark plug wires look like on an older Pontiac. Vehicles before the 2000s have spark plug wires.
Step 7: Remove the connector will be different for your individual car. For this Kia, I needed to slide a tab out of the way and then press on the middle of the connector to release it.
Step 8: Locate the bolt securing the coil on plug to the engine. Remove the bolt and gently pull up the coil on plug. Be careful not to pull too hard and tear the plug this is especially important on the more frail spark plug wires. Repeat until all of the coil-on plugs are removed.
The picture shows the spark plug in the spark plug well which will need to be removed. The oil that can be seen in the picture is from the valve cover gasket failing and needing to be replaced. A tip before proceeding. When performing step 9 if the spark plugs do not budge or are really hard to turn let the spark plug sit with penetrating oil in the spark plugs wells. Spark plugs that have not been changed for a while can become seized in the engine and by using penetrating oil can prevent damage to the engine.
Step 9: Once all coils/wires and spark plugs are removed carefully insert a 5/8th socket or the socket size for your car (see your owner’s manual) into the spark plug well. I use a special spark plug tool if one does have a spark plug tool a standard socket will work but a telescoping magnetic pickup tool will be needed to remove the spark plug. Make sure when removing the spark plug that the socket stays straight.
Although not too visible on the plug I added dielectric grease to the spark plug tip to prevent the coil on plug from seizing to the spark plug.
The picture shows the dielectric grease I used for the project. Here is a link to it as well: https://a.co/d/8WXRIMJ
Here are the steps to put everything back together
As can be seen in the photo the tool keeps the socket centered and has a magnet which allows the spark plug to be easily pulled out and the new one to be easily lowered into the spark plugs well. The tool can be purchased here: https://a.co/d/boCCUmK
Step 1: Lower the spark plug down into the spark plug well and tighten each one to specification before reinstalling the coil on plugs. As a note, I could not successfully torque down the spark plugs because I used penetrating oil to remove the stuck spark plugs. The penetrating oil can result in over-tightened bolts so I only tightened until snug. Reference the owner’s manual or repair guide to torque the spark plugs to the correct torque, however, do not over-tighten a snug fit will suffice.
Step 2: Seat the coil-on plugs back into the spark plug well. Ignore the connector at this step because the connectors will be attached after all the coil-on plugs are seated.
Step 3: With the coil on plugs being mostly plastic using a torque wrench may not work as the plastic can stretch so tightening until snug is sufficient. Again do not worry about the connectors at this point. The connectors will be easier to plug in when the coil on plugs are properly bolted down.
Step 4: Now that the coil-on plugs are all seated and tightened down the connectors can be put back onto the coil-on plugs. A soft but audible click can be heard when the connector is seated all the way on.
Step 5: If the vehicle has a vanity cover now is the time to put it back on. The vanity covers are typically plastic and can be brittle from the operating temperatures of the car so take it slow and be careful when installing it back on.
Step 5: This is the last step under the hood so make sure no steps were skipped. If everything was completed then it is safe to reconnect the negative wire back onto the negative battery post.
The last part of this guide is to test the installation for success by starting the car and making sure no check engine lights appear and that the car is running normally.