Changing Spark Plugs on a
4.0L V6 Ford Explorer


Contributed by D. Borch

When I first opened the hood of my '96 Explorer, I was a bit intimidated by the well-hidden spark plugs. I've done most of the regular maintenance on all the cars I've owned in the past, but this looked like a challenge. Before I new it, 50K had clicked over and it was time for new plugs. I did some research and got a lot of good advice, but I discovered that with the proper tools, it's not such a challenging task after all.

Three tools are an absolute must. First and foremost, you gotta get a 5/8" universal spark plug socket. Don't try using a regular socket and a universal adapter, spend a few bucks and get the right tool. I got mine at Auto Zone plenty cheap and nothing else will work as well. A decent boot puller will save broken wires and mashed fingers; my right ring finger had a black nail for month when a stubborn boot finally came loose, directly towards the power steering pump. You'll also need a short length of rubber tubing to simplify installation of the new plugs. The only other basic hand tools you'll need are a 3/8 ratchet and a variety of extensions.

Start by removing the duct from the air filter box to the engine intake. Two hose clamps and a few other connections are all that hold it in. It also helps to release the clamp on the air cleaner box, then remove the inner box half (be sure to unplug that wire harness) and the filter itself to get a little more elbow room. That's all the extra disassembly required. Get your new plugs ready by checking the gap and apply a bit of antisieze grease to the threads. I went back with the stock Motorcraft platinum plugs, considering the very good condition the old plugs were in after 50K miles. I started from the front plug on the passenger side. Use the puller to remove the boot. If it's stubborn, try a little silicone spray and twist it until it moves. NEVER pull on the wire itself. If you have access to compressed air, try blowing around the plug to remove any debris. A small brush may also help. Use the ratchet, socket and whatever extension (if necessary) works best to remove the old plug. When it's out, check the condition of the firing end. Look for excessive deposits, blistering or cracking, or oil residue. A dry, beige or gray looking insulator and slightly worn electrodes are what you are hoping for. Keep track of which cylinder each plug came from to trace any possible problems down.

Remove and replace the rest of the plugs in the same manner. When removing the back plug on the passenger side, you may want to remove the entire wire first, since it is quite short and easily damaged. The driver's side of the engine is where that swivel socket will be indispensable, be especially careful around the EGR manifold blocking the plugs. Stick the short piece of rubber tubing on the new plug to ease installation. Take your time and don't cross-thread. Also follow the torquing procedures that came with the new plugs, because the head is aluminum and the threads are easy to strip, which will absolutely ruin your day. I little silicone grease in the boots before installation will make the next removal a little easier. Replace the filter and duct and fire it up. If you were careful and didn't cross any wires, you should have no problems.

I have heard some suggest going through the wheel well to remove the back plugs. That may work, but I didn't have to. You will need to climb up on the engine a bit though, so watch where you step. By the way, since you have that air filter out, when was the last time you changed it?


Contributed by Matt F.

You know it ... Plug #3 ... the one all the way in the back that you can barely see without an inspection mirror. It's actually angled backwards, so you can break the ceramic on it pretty easily if you're not careful. I used a socket cap, which goes into a socket so that you can turn the socket with a wrench, and it came out and went back in like a breeze. For readers who don't know what a socket cap is, it's a little plug that goes into the socket, so that you can turn it with a wrench in very tight spaces.

Btw, the guy who said take the airbox off first was RIGHT ON. It takes about two minutes to get that box off and on, and it clears up a whole lot of room for you.

oh hey - another tip: when I replaced the plugs and cables, I wrote the mileage right on the cables with a permanent marker, so there's no guessing how old they are.


 

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Updated February 16, 2001

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