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Old 01-12-2014, 04:59 AM   #1
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Ford 5.4 #8 Plug R&R

A recent post asking how best to access & remove the #8 spark plug in 5.4's typical to E-Series prompts this thread. Having once been new to this myself I remember how difficult it looks trying to service that plug and COP at first glance.

What follows is my method that may be helpful to someone facing this task for the first time. I've listed tools used, either by description or a brand name/part number if its important to this process

Assumptions are made the general procedure for changing plugs is already known so we'll concern ourselves only the the typical #8 plug here.

I've included side thoughts or further descriptions as an FYI for those who like small details.

If any of this seems redundant or common knowledge keep in mind it's not for a first-timer.

Read it through several times, get the procedure in mind before digging in. Being honest though it takes longer to read this than to do the actual job!

And we begin..................

-Carefully disconnect COP wiring harness connector, lay it aside.

-Use a1/4” drive 7MM socket, ratchet and 6” extension remove the COP hold-down bolt. (Several 5.4 COP's are held in place with this bolt threaded into brass inserts press-fitted in the plastic intake manifold. If significant resistance is felt during removal a shot of PB Blaster or a thin spray lubricant on its threads should be used before continuing removal. Go slowly here.)

Close up showing socket on bolt head, notice position between fuel rails etc:

A small magnet, maybe one of the extendable handle types is handy to have ready if its needed to retrieve a dropped bolt.

Replacement bolts: Ford p/n N606500 S8 about $5 each or M5 x 0.8 x 25mm bolt.

Notice the tube assembly that's slipped out of its normal support. Since this tube can move up and down slightly the extension length can vary from 2” to 6” or longer still giving easy access. Personal preference or your own tool selection here---use what you have that fits. Be sure to replace the tube in its support upon completion of this task.

-COP can now be lifted up and free of the boot/spring, slid out between the fuel rails and valve cover--more than enough room. A large wire bundle running on top of the valve cover may require moving the COP a bit forward until it slides out easily---nothing difficult.

-A simple pair of 8” straight needle nose pliers inserted as shown between the fuel lines easily grabs the boot for removal:

-Once free of the plug the boot easily slides out much the same as the COP:

If the boot is old or hasn't been changed in forever it might resist pulling free from the spark plug porcelain element. If the boot is old it might tear into small pieces as its removed. When I encountered this situation a long thin pointed probe, small tipped long blade screwdriver or anything else that can be inserted between the boot and spark plug porcelain without damaging the cylinder head works just fine. If you've already planned replacing the boot & spring its not necessary to be too careful with the boot but it still has to be completely removed.

NAPA/Belden USA made boot & spring #702418 is an excellent replacement part--about $5 each at time of this post.

There are dedicated tools like Schley's #68450 available for about $35 online or the local tool outlet too--check around. Essentially these tools fit snugly over the plug porcelain between the boot releasing it from the plug as its seated. The torn boot stays on the tool as its removed.

-Once the boot is completely removed its advisable blowing out the cylinder hole to remove any debris, moisture, lubricant etc etc. This step should be part of each plug's removal, mentioned again only as a reminder.

-Switching to 3/8” drive my Snap On dedicated 5/8” plug socket S9706KRA with universal joint already attached is fished inside the plug hole. At this point its not necessary that it perfectly aligns on the plug's hex.

A 6” 3/8” extension easily fits between the fuel rails as shown below. Plug the extension into the U-joint and turn until these fully index on the plug hex:

(If you feel its absolutely necessary to move the fuel rails the highlighted 8MM flange headed bolt highlighted can be loosened or removed giving some sideways movement. Honestly its not enough to really do much good, just suggested as a possibility. Proper selection and placement of tools makes all this very doable without removing any other parts--our original goal.

-Remove the old plug and prepare to install the new one. Using slow steady force rotate the old plug out---if any significant resistance is felt STOP turning! Remove the socket and squirt PB Blaster or something similar into the plug hole (don't fill the hole full) allowing it to soak in for a few minutes. An alternative and probably better product would be any good carbon dissolving spray, typically sold as carburetor cleaner. Make certain it has carbon dissolving properties as its main function.

Resume by tightening the plug then backing it out once again, repeating this “rocking” action until the plug twists out freely. If it takes a few cycles of this its not uncommon, to be expected occasionally, nothing to be overly concerned about at this point. These helps break any carbon deposits etc loose from the plug threads. Proper installation of the new plug including correct torque is dependent on this step.

(As a side note there is speculation HOW a plug is removed can conceivably cause thread damage leading to a blown-out plug. Being careful during removal is just as important as proper installation of plugs into aluminum heads---be advised.)

(There is an excellent video useful to this entire procedure however it was originally created with the newer 3 valve per cylinder heads. Despite that though all the info there transfers perfectly to the 2 valve engine plug change---its worth watching even though there are some differences between my suggestions and the video due mostly to the different heads and plugs:

I use Loctite nickel-based anti-seize on the new plug threads and slowly pull them to 22 ft/lbs torque. Some believe anti-seize is unnecessary with platinum plugs but its never caused me any issues. If you're changing plugs at 50K miles it might not be absolutely necessary---longer intervals and its more advisable, IMHO.

Double check the plug electrode gap, adjust as necessary.

I'll use a piece of rubber tubing slipped over the plug's upper contact end to start threading it into the head. Since the tubing is flexible it's not in the way when placing the plug into its bore. There's an added benefit with this too: greatly reduces the chance I'll cross the threads!

Because the tubing doesn't allow much turning force any resistance is easily felt in the fingertips. The rubber tube prevents a potentially cross-threaded plug being tightened and damaging the head.

If the plug won't thread in easily try backing it out and realigning it to the cylinder head threads again. Repeat as many times as needed until you feel smooth thread engagement; The plug should thread in with the rubber tubing requiring nothing more than finger pressure.

-Torque the plug to your preferred setting--I use 22/ft/lbs or it's metric equivalent:

At first click I stop because that's my optimum setting. (Wrench shown is my Wright Tools #3479---I like their torque wrenches for several reasons. Its length gives me a good “feel” for my plug torque settings & its range of approximately 5-75 ft/lbs will give maximum accuracy at 22 ft/lbs. This model uses the Newton meter and in/lbs scale which is easily converted into ft/lbs---I bought this one dirt cheap, USA-made and nothing but a top quality tool.)

Using a dab of dielectric grease on both ends of the boot, assemble it onto the COP--don't forget the spring contact. This all fits under the fuel rails just like everything else so far, drops easily onto the plug:

Not shown is the COP & boot being seated by gently pushing downward until its fully seated. I'll use a socket attached to an extension because it gives straight downward pressure--fingers don't fit too well. If there's more than 1/8” or so between the bottom of the COP tab and the head re-check the boot, spring etc---there shouldn't be an excessive gap here.

Switching back to the 1/4” drive 7MM socket and ratchet replace the COP bolt. A dab of anti-seize or dielectric grease on the threads helps future COP servicing. Be careful to NOT over torque this bolt; slightly more than finger-tight with the 1/4” ratchet should be tight enough.

Carefully align the wiring harness connector with the COP opening carefully insert and seat it into the COP (Small dab of dielectric grease here too please.). The locking tabs of older connectors are prone to break potentially causing a full or intermittent misfire. Listen for the audible click or feel the connector seat into the COP and test the fit by slightly pulling backwards--it should hold in place.

Replacement connector is an NAPA EC259 or equivalent.

Start the engine, listen for any signs of misfire, CEL light etc.


So that's pretty much it. While there might be a few variations across the model years this as shown works for the '97 > '03 models but most likely all the way through end-of-life vehicles, 2014?

Because E-Series never received the 3 valve-per-cylinder heads we don't have that to deal with---it can be a quite the mess according to posts in the Modular Motor forums. (FWIW the embedded video is primarily about the 3 valve heads.)

Please feel to add anything or point out mistakes----glad to edit or add anything as needed. Comments are also welcome.

Thanks for reading!

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Old 01-12-2014, 09:48 AM   #2
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Re: Ford 5.4 #8 Plug R&R

Thanks JWA, very nicely done post and great resource. It's probably the same for the V10's too right? Or are they more roomy towards the back? Either way, thanks!


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Old 01-12-2014, 10:27 AM   #3
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Re: Ford 5.4 #8 Plug R&R

Thanks Scotty----'ppreciate the compliments!

Not sure about the V10 but if the F-Series guys are any indication those engines tend to be more crowded at the front rather than the rear. Pure speculation on my part but if anyone looking in can or already has a photo of their V10 in a van with the doghouse removed that could add to this as a resource.

Post 'em up if ya got any!
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