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J

Jason Cronin

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I'm not sure if anyone has came across this. But I figured I would post about it anyways just in case. At least for us that have the 2006 and up ST.



Last month I went on a 1000 mile trip. I noticed the MPG and I was only getting 17 to 17.5 highway MPG. Before I was getting 18 to 18.5 I only had a little over 40,000 miles. So I started looking into it. I also calculate it myself and the trucks computer is dead nuts on.



Even though the Spark Plugs are supose to be 100,000 mile plugs I still decided to change them. Well I'm glad I did. I went to autozone and bought the Autolite HT (didn't have much choice since motorcraft was the only other plug). Got them home started to changge them out. I compaired the 2 plugs and there was a big difference. The stock Motorcraft plugs were worn out. 100,000 mile plugs my foot. Every single one was bad. And they did not put anti-sieze on them. I was told that before. So if you have a gen-2 ST. Be very careful taking the plugs out.



Well I went on the 1000 miile trip again. Not only did I get my milage back. I gained 1 MPG on top of that. So now I am getting 19 to 19.5 MPG on the highway.



So if you have a gen-2 and you are noticing a milage drop. Change those plugs out. Yes the Autolite HT's cost more. But is it worth it.



And be very careful getting them out. I was told because of the way they are designed and the fact that there was no anti-sieze on them, they will brake in the head.



Sorry it was a long post. I just wanted to get that out.



 
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Anti-seize applied to the plug threads is not a good idea. It can and will prevent the plug from making good contact with the cylinder head and therefore have a poor ground which results in decreased performance of the spark plug. A properly torqued spark plug taken out of an engine after it has cooled should never be an issue. Also i am surprised that your 40k plugs were that worn out. Did you measure the gap on the plugs that you took out of the engine? I sure hoped that you gapped the plugs you put in. Just because they said they were for your truck doesn't mean that they were properly gapped. I have checked plugs on ALOT of Ford vehicles with over 60k on them and find that the plugs are barely worn. Something just doesn't make sense here
 
You cant tell if a platinum plug is worn out by sight. It might have the wrong gap or discolored depending on A/F ratio or fuel qaulity detergents.
 
FWIW, I am 99% sure Ford reccommends anti-seeze lubricant on the plugs to protect the aluminum heads from galvonic corrosion between the two dis-similar metals. I have known of people removing the threads with the spark plugs because they did not use anti-seeze lubricant.



What do I know?



I would never put a spark plug into an aluminum head without anti-seeze and NEVER put a plug into an iron head without motor oil on the threads.





Tom
 
SECTION 303-07A: Engine Ignition 4.0L SOHC 2008 Explorer/Mountaineer/Explorer Sport Trac Workshop Manual

REMOVAL AND INSTALLATION Procedure revision date: 06/21/2007



--------------------------------------------------------------------------------



Spark Plugs Printable View (92 KB)



Special Tool(s) Remover, Spark Plug Wire

303-106 (T74P-6666-A)



Material Item Specification

Silicone Brake Caliper Grease and Dielectric Compound

XG-3-A ESE-M1C171-A



Removal and Installation



CAUTION: It is important to twist the spark plug wire boot while pulling upward to avoid possible damage to the spark plug wire.



NOTE: Spark plug wires must be connected to the correct spark plug.



With a twisting motion, use the special tool to pull the spark plug wire from the spark plug.



NOTE: Use compressed air to remove any foreign material from the spark plug wells before removing the spark plugs.



Remove the spark plugs.

To install, tighten to 17 Nm (13 lb-ft).

Use a suitable spark plug gap tool to check and adjust the spark plug gap.

NOTE: Apply silicone dielectric compound to the inside of the spark plug wire boots.



To install, reverse the removal procedure.





--------------------------------------------------------------------------------



Here it is straight out of the FORD WORKSHOP MANUAL. FWIW I don't believe that there is any auto mfg that says to put anti-seize on the the spark plug threads. But then again what the hell do the engineers who built these engines know, and if I am not mistaken the main reason is because of breakdown of the ground between the spark plug and engine block. I can tell you from experience though that I have cured ALOT of misfires by cleaning the anti-seize from the plug threads.



If you have anti-seize on your plugs just spray them off with some brake cleaner, as for the holes about the best you can do is get a rag wet with brake clean in the hole and twist it around.



Also on the new 3 valve motors Ford does recommend anti-seize but not on the plug threads, you are only to apply it the electrode shield itself so nothing will stick to it, this is what is causing the plugs to not come out of the cylinder head after they have been unscrewed.





If the threads of the sprak plug hole come out with the plug then the engine was not properly cooled off before the plugs were removed, the plugs were crossthreaded when they were installed(this happens alot to DIYers because the plug will actualy thread in somewhat ok) or when they were installed they were overtorqued...































 
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You can not regap these type of plugs. They are pregaped and set. And yes, the plug did ware. Here is a pic of them. Sorry its hard to see detail. But I took it on my phone camra.[Broken External Image]:
 
From what I could see from his photos Countrydevil has a V8. The plug removal/replacement procedure listed for the 4.0L is quite different from the 4.6L. Also from the manual:



SECTION 303-07B: Engine Ignition 4.6L (3V) 2007 Explorer/Mountaineer/Explorer Sport Trac Workshop Manual

REMOVAL AND INSTALLATION Procedure revision date: 08/14/2008



--------------------------------------------------------------------------------



Spark Plugs Printable View (111 KB)



Material Item Specification

High Temperature Nickel Anti-Seize Lubricant

XL-2 ESE-M12A4-A

Motorcraft Carburetor Tune-Up Cleaner (aerosol)

PM-2

Motorcraft Carburetor Tune-Up Cleaner (fluid)

PM-3

Silicone Brake Caliper Grease and Dielectric Compound

XG-3-A ESE-M1C171-A



Removal



Disconnect the ignition coil electrical connector.

NOTE: When removing the ignition coils, a slight twisting motion will break the seal and ease removal.



Remove the bolt and the ignition coil.

NOTICE: Do not remove the spark plugs when the engine is hot or cold soaked. Spark plug thread or cylinder head damage can occur. Make sure the engine is warm (hand touch after cooling down) prior to spark plug removal.



NOTICE: Only use hand tools when removing or installing the spark plugs or damage can occur to the cylinder head or spark plug.



NOTE: Use compressed air to remove any foreign material from the spark plug well before removing the spark plugs.



Remove the spark plug in the following sequence.

Loosen the spark plug no more than one-eighth to one-fourth of a turn.

NOTICE: Excessive use of carburetor tune-up cleaner can introduce enough liquid volume to hydro-lock the engine.



Using carburetor tune-up cleaner, fill the spark plug well until fluid has reached the spark plug jamb nut. Follow the directions on the packaging.

NOTICE: Do not loosen or tighten the spark plug for a minimum of 15 minutes or damage to the cylinder head or spark plug may occur.



Let the carburetor tune-up cleaner soak for a minimum of 15 minutes.

NOTE: Some screeching and high effort may be noticed and is normal.



NOTE: The expected removal torque is around 45 Nm (33 lb-ft).



Tighten, and then loosen the spark plug, repeating until turning effort is reduced, and remove the spark plug.

Inspect the spark plug. Install a new spark plug as necessary. For additional information, refer to Section 303-00.

Installation



NOTICE: The spark plug gap is NOT adjustable. Damage can occur to the ceramic if the spark plug gap is adjusted. Install a new spark plug if the gap is out of specification.



NOTE: Refer to the specifications in this section for correct spark plug identification.



NOTE: Do not apply high temperature nickel anti-seize lubricant to the spark plug ground strap area.



Apply high temperature nickel anti-seize lubricant to only the spark plug ground electrode shield as shown.



14a0795364df21c3d0cf1c41b9532c66.gif






NOTICE: Only use hand tools when removing or installing the spark plugs or damage can occur to the cylinder head or spark plug.



Install the spark plug.

To install, tighten to 34 Nm (25 lb-ft).

NOTE: Verify that the ignition coil spring is correctly located inside the ignition coil-on-plug boot and that there is no damage to the tip of the boot.



Install the ignition coil and the bolt.

Apply a light coat of dielectric compound to the inside of the ignition coil boots.

To install, tighten to 6 Nm (53 lb-in).

Connect the ignition coil electrical connector.

 
Well I would like to thank everyone for the added input. I feel the more info we can share with each other will help someone down the road. I like this site and go to it everyday.



I have been studying, and repairing cars and trucks for 20 years. And I still believe you learn something new everyday. Lets keep this good info going. Be respectful to each other. And have fun.



Thanks to all the sponsors for putting this site up.
 
Not to disagree with the manual. I have used a copper based anti-seize for years. sometimes grafite base. I only put very minimal amount on the first 3 to 4 threads. Depending on thread length. I believe that way I still get a good ground at the seat area. IMO, the seat area makes a better ground than the threads anyway.
 
ncranchero,3/15/2009 09:41 MT



From what I could see from his photos Countrydevil has a V8. The plug removal/replacement procedure listed for the 4.0L is quite different from the 4.6L. Also from the manual:



SECTION 303-07B: Engine Ignition 4.6L (3V) 2007 Explorer/Mountaineer/Explorer Sport Trac Workshop Manual

REMOVAL AND INSTALLATION Procedure revision date: 08/14/2008
Click to expand...



Now I realize that he has the 3 valve v8 but I did cover that in my post.
 
Strange thing is. When I was at Autozone we looked up the plugs for the V6 and it was the same. Autozone may have the wrong info. But yes I do have the V8. Sorry I should have added that.



I use Alldata for my info.. Its great. Plus there isn't a book yet that I have seen for the Gen-2 ST.
 
Now I realize that he has the 3 valve v8 but I did cover that in my post
Click to expand...



Yes you did, somewhat. I've never had a 3 valve 4.6L with these style plugs so I learned something from my own posted info. That removal procedure was new to me so I just thought I'd put it out there in case anyone wasn't familiar with it. ;)
 
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Removal and Installation



CAUTION: It is important to twist the spark plug wire boot while pulling upward to avoid possible damage to the spark plug wire.



NOTE: Spark plug wires must be connected to the correct spark plug.



With a twisting motion, use the special tool to pull the spark plug wire from the spark plug.
Click to expand...





Uh, I don't think any of the wires would reach the wrong plugs on my truck. This seems impossible.



Oh, nevermind. Thyis was for V6
 
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