Maintenance: Changing Spark Plugs

At the time of writing, my Explorer has 67,000 miles on it. I’m planning another cross-country trip, so I wanted to replace the spark plugs earlier than Ford’s recommended 100,000-mile interval. I recall changing the spark plugs on a Tundra 4.7L engine and an Xterra, both of which were quite simple. I watched a few YouTube videos on changing spark plugs for the 3.5 EcoBoost, and they all seemed straightforward. However, I was in for a surprise – replacing these spark plugs was actually quite challenging! With some patience, I managed to change all six. Here’s how I did it:

What I used:

Step 1: Disconnect negative terminal from battery

Disconnect for safety reasons.

Step 2: Remove engine bay cover.

Remove oil cap.

Lift the plastic engine bay cover upwards, it’ll pop off.

I reinstalled the oil cap to prevent debris from falling inside. For this part, we’ll concentrate on cylinder #6 because it’s the easiest to access.

 

Step 3: Disconnect the ignition coil

You’ll need to pull down the red tab with a flat head screwdriver. You have to be extra careful when disconnecting the electrical plugs, since these plugs can be fragile and even more true as they age.

Once the red tab is pulled down, you’ll need to push down on the grey plastic tab and pull the entire plug back. If it’s being stubborn there’s a trick, which is to push in the plug first and then pull out the plug.

Remove the 8mm bolt.

Step 4: Remove Ignition coils

In a perfect world, removing the ignition coil would require a light tug and it come off just like on my previous Xterra. But sadly, pulling these coils requires some effort to take off. It seems like the boots somehow forms a perfect vacuum on the the spark plug. After trying so many different methods, I ended up using a string to remove the stubborn coils. 

I tucked the strings under the plastic tab and then pull it upwards. The wider the string the better. I couldn’t find a wider string but I discovered if I looped my string twice creating 4 strands it becomes even more studier. 

Step 5: Stuck Boot

If you didn’t get a stuck boot, please move to the next step. I was only able to successfully remove 3 out of 6 coils with the boots attached. The only cylinders that had a stuck boot were cylinders 1, 2, 3 (closest to the firewall). Here’s my experience with removing the stuck boots:

Long reach needle nose pliers.  The most obvious method, but it did not work for me. The boots were stuck onto the spark plug so tight I ended up tearing the boot into pieces when using the needle nose pliers. You can try this method, but don’t be surprised if you end up tearing a piece of the boot off.

Metal hook method. I created a metal hook from a thick metal rod (just slightly thicker than the wires used on shopping carts) and sharpened the tip with a grinder. Then I fished the boots out. After, I used compressed air to blow out any small rubber debris out of the chambers. I used this method for all 3 of my stuck boots.

I discovered there are other methods of removing a stuck boot. It’s a shame that I learned about this 7/16 socket method only after I changed the spark plug, it could have save me so much time. 

  • 7/16 socket method. Use a 7/16 socket with an extension and insert it onto the top of the boot, be careful of the middle spring. Push down until you hear a pop and then pull the socket out. If done correctly, the boot should come out with the socket. Video link.
  • Matco Ripped Spark Plug Boot Remover MST6845. Similar to the 7/16 socket method but Matco has a tool for this!  Video link.
    • Schley Products Ripped Spark Plug Boot Remover.  Similar tool to the Matco MST6845 and it’s available on Amazon. Product link.
  • 5/8 hole saw method. Only use this method when you’re desperate. Attach a 5/8 hole saw to a drill and then shred away the rubber boot. Use compress air to remove the debris. Video link
Step 6: Remove spark plug

Insert a 5/8 socket with extension and remove the spark plug.

Tada! Spark plug finally removed.

Step 7: Install new spark plug

I wrapped electrical tape around my 5/8 spark plug socket to prevent it from disconnecting.

Insert the new spark plug into the 5/8 spark plug socket.

Hand thread the spark plug so it doesn’t cross thread.

I’ll finish off the tightening of the spark plug with a torque wrench. These spark plugs are suppose to be torqued at 11 ft/lb. It’s hard for me to judge how tight 11 ft/lb, is  so I used a torque wrench. I’m glad I did because it didn’t take much to tighten them. 

Step 8: Install new boots on the ignition coil

I replaced all 6 of my boots. The boots can be easily removed by bending them off.

New boots installed.

Lastly, I added some dielectric grease into the boot so it’ll be easier to remove next time. 

Step 9: Reinstall ignition coil

Insert the ignition coil, tighten the 8 mm screw, and reinsert wire clip.

Experience replacing specific spark plugs

In this part of the blog, I’ll be letting you know my experience on removing and installing spark plugs specific to the cylinder.

I’ll be starting at cylinder #6 since it’s the easiest to access.

Cylinder #6

In this blog, we offer a step-by-step guide on how to remove the spark plug from cylinder 6. If you need a reminder, just scroll up to see the detailed instructions. Remember that cylinder 6 has the easiest-to-reach spark plug, so removing other spark plugs might be more difficult.

Cylinder #5

To remove the ignition coil, this foam cap needs to be taken off.

It can be removed by hand, simply lift it off.

Remove spark plug. 

Cylinder #4

There is a hose that is blocking the removal of the coils.

This hose easily comes off by sliding the small grey lever down and then pulling on the hose.

Cylinder #1

Remove this hose to access the spark plug in cylinder #1.  To remove the hose you should be able to slide the grey tab back.

Cylinder #2 

These two wires will need to be detached to access the spark plugs in Cylinder #2. 

I used a fastener removal tool to detach the two plastic fasteners. You can use pliers too if you don’t have a fastener removal tool. 

Cylinder #3

You’ll need to detach plastic PVC pipe from the rubber hose to reach this spark plug. Detaching the hose allows you to slightly move the pipe out of your way. The blue circle in this picture is what you’ll need to loosen or remove to detach the pieces.

Here’s a picture of it detached. 

Finally, the last spark plug removed. 

Conclusion

Removing these spark plugs proved to be more challenging than anticipated. The primary difficulty stemmed from the boot remaining stuck to the spark plugs during removal. Even worse, sometimes the boots would detach from the coil but stay stuck to the spark plug, prolonging the process. Thankfully, with persistence, I managed to remove them completely. I don’t expect to replace the spark plugs again anytime soon, but applying dielectric grease to the boot should make the task easier in the future.

Have you encountered any issues when changing spark plugs? If so, what techniques worked for you? Please share your experiences in the comments.

8 thoughts on “Maintenance: Changing Spark Plugs”

  1. Hi Midas…
    Nice write up on changing the spark plugs… It was very helpful for me…
    I just did this on my wife’s 2017 Explorer Sport…
    The hardest plug to change was #3, but I managed to complete the entire job without having to fight the boot issue… I also added dielectric grease to each boot…

    Tomorrows project, I will be to changing the rear axle / differential fluid….

    Reply
    • Hi Chuck! Welcome back. Are you saying you were able to change all 6 spark plugs without the stuck boot?! Lucky you! Also how did you remove the coils? Were they difficult for you too?

      Reply
  2. Removing the coils were not a problem for me… Gave them a slight 1/4″ rotation back and forth and they came right out…. no damage to any of the boots…I noticed a white film on the ends of the boots, so maybe Ford is adding some form of release…. I did add a small amount of dielectric grease before I reinstalled each coil….

    Not to change the subject, but I wanted to change the rear axle / differential fluid… There is only a fill plug, no drain plug… And not very much room with the exhaust… Looks to be a PITA…

    Reply
  3. Awesome post!

    I have a 2016 Ford Explorer Sport and I was able to replace all the plugs but the #3. I was afraid to damage something, but with your guide I’m sure I’ll be able to get it done! Thanks!

    Reply

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