Spark Plug Replacement

[Steeda90GT]

I might want to add that Borg Warner made plenty of OEM parts for Ford, including their T5 manual transmission.

 

[vweathers]

1999 4.0L OHV spark plugs and wire set

I just finished replacing the plugs and ignition wires on my 1999 4.0 liter OHV Explorer. After reading the posts on this board and looking at the engine compartment clearances, I decided the best approach was to remove each front wheel in turn and the plastic splash guards inside the wheel wells.

Its easy to unfasten the back halves of the splash guards by just popping the three rear-most plastic fasteners loose and folding the guards out of the way. This will give you fairly easy access to the plugs and wires.

I spent more time trying the thread the new wires into place than removing and replacing the plugs. On the OHV engine, the driver's side of the engine compartment is much more cramped and difficult to access than the passenger side.

I finally discovered the best way to thread the driver's side wires into place was to slide a 3/4 X 24-inch fish-tape up from near the exhaust manifold to the top of the engine, then tape the plug-end of the new ignition wire to it and pull the tape and wire back down into position.

I worked on the driver's side of the engine first, and took 2 1/2 hours to finish it, including my time deciding how to begin, and futzing around trying to figure out how to snake the new wires into place.

The passenger side of the 4.0 liter OHV engine is a piece of cake, and I only needed 30 minutes to complete the job on that side.

At least for the OHV engine, there's no question that it is much easier to work through the open wheel wells than going through the contortions necessary to work on the plugs and wires from above the engine. In addition, you also have the opportunity to check the condition and wear on the front brake pads at the same time.

 

[yingling]

Anti-seize on threads

DO NOT USE ANTI-SEIZE. That's the quickest way to rip the threads out of the head.

The system is designed with a specific torque spec selected to get the optimum clamping force on the joint as wella s resist loosening due to vibration. Anti-seize lubricates the threads, reducing the torque needed for any given clamping force. Reduced clamping force yields a reduction in the resistance to loosening.

Completely unnecessary, and not recommended by Ford. In fact, the service manual specifically states NOT to use any lubricants on the threads.

I did mine at 100,000 miles for the first time. I did them stone-cold. I had zero issues with the plugs being stuck in the heads.

Hello, Can you please direct me to the section in my 1997 explorer manual that makes this statement. Thanks, Joe

 

[Fox Fader]

I used anti-seize on my 05, I also have never used a torque wrench when istalling plugs. Since these are washerless when the plug stops that's it, I just make sure it's snug.

It's a little tricky on the 97 OHV, but I went through on top to change them. Swivel joints really come in handy here. The 05 has more engine bay room which makes it quite easier.

 

[marragtop]

I agree you should not use a lubricant such as oil or WD40 on plug threads. When heated, the lubricant will bake and cause a bond between the plug and head which will create problems. However, anti-seize does not fall into that category. You can remove a plug or a bolt 50k miles later and the anit-seize is still in its original state and not hardened.

 

[gijoecam]

Hello, Can you please direct me to the section in my 1997 explorer manual that makes this statement. Thanks, Joe

Nope. Would you care to the portion of the owner's manual OR service manual where it states you should use anti-seize on the spark plug threads?? (Hint: Doesn't exist)

But I can direct you to the portion of the service procedure where it does NOT instruct you to use any lubricant on the threads. Would you care to direct me to the portion of the owner's manual where it lists the torque spec for the plugs? (Can't? Well, then, how do you know how tight to make them??)

I agree you should not use a lubricant such as oil or WD40 on plug threads. When heated, the lubricant will bake and cause a bond between the plug and head which will create problems. However, anti-seize does not fall into that category. You can remove a plug or a bolt 50k miles later and the anit-seize is still in its original state and not hardened.

When the engineers designed the motor, they selected a particular torque spec for the original dry threads that would generate a particular clamping force between the tapered sealing surface of the plug and the head. The lubricant on the threads lowers the torque necessary to reach any particular clamping force. Exactly how much? It's anyone's guess.


To reach the same level of clamping force, you need a lower torque for a lubricated thread than for a dry thread. If you go to the same torque with a lubricated thread as you would for a dry thread, you run the risk of exceeding the clamping force the threads are designed to withstand, and can, in fact, rip the threads right out of the head. (It's all too common on the 4.6L and 5.4L motors, in part due to the fewer threads in their heads, and in part due to people using anti-seize on the threads.... Those are two of the engines that specifically call for NO lubricant of any kind on the threads)

Now, say you opted to go with a lower torque because you've chosen to lube the thread... How low is low enough to not jeopardize the threads, but high enough so that the plug doesn't vibrate itself loose? Done any testing to ensure that doesn't happen? I can guarantee the engineers that designed and tested the engine made an educated engineered estimation of the necessary torque for DRY threads, then did testing to see what the turn-out torque was after 100,000 simulated dyno miles. In all likelihood, they also did corrosion testing to ensure they could be removed after 5-7 years without corroding in place. Throw a thread lubricant into the mix, and all their testing goes out the window.

 

[sne43]

I posted another thread with similar steps. I included my technique for cutting boots off of spark plugs that have been installed for over 100K miles. There was no other way.

http://www.explorerforum.com/forums/showthread.php?t=245561&highlight=replace+spark+plugs

While I am posting, I used anti sieze as well without the knowledge provided until after the fact. I will post back when I change the plugs at 200k and after seeing what they look like.