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Changing Spark Plugs on 91-94 Explorer

Discussion in 'Stock 1991 - 1994 Explorers' started by MrQ, October 18, 2008.

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    1. MrQ

      MrQ Take the Bull by the Horns Moderator Emeritus

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      I looked for a decent spark plug change how-to on here, but was unable to find one. Well, I just recently replaced mine and took some pics. Hopefully this guide will give everybody a heads-up on doing this.

      By replacing your plugs and wires you can potentially increase your gas mileage and extend the life of your engine. You should also gain some power if yours haven't been replaced in a while.

      (If I erred and somebody has already done this, then just take it as my spark plug project :D )

      Step 1.

      The tools and parts you will need are:

      - A 3/8 socket wrench
      - A long 5/8 socket
      - Several lengths of extenders for the socket wrench
      - 6 spark plugs (I used Bosch Plus Copper Cores)
      - A set of spark plug wires (Again Bosch)
      - Your Exploder jack and accompanying accessories(Located in the compartment in the rear on the driver's side) OPTIONAL
      - A jack stand (for safety) OPTIONAL
      - Several pieces of wood (I used 4 pieces of plywood) OPTIONAL
      - Liquid Wrench or other anti-seize chemical
      - Dielectric grease
      - Gap Setter
      - Flat-head screw driver
      - Light

      [​IMG]

      2. Ok it's time to put your Ex on a level surface and pop the hood. Familiarize yourself with where the spark plugs are. Remove the intake hose from the air filter and the intake manifold. Then remove the vacuum tube to the oil fill from the intake hose. Disregard removing the radiator hose. This diagram should help:



      [​IMG]

      3a. Remove the spark plugs on the driver's side: DO NOT DO ALL THE SPARK PLUGS AT ONCE!! Take one spark plug at a time. Remove it, remove the wire (twist left and right if it is hard to get off. Make sure you grab the boot at the base not at the top!) and measure it up to the new wire in the Spark Plug wire set. Apply the dielectric grease to the inside of the rubber boot ONLY!! Do not get it on the metal connector in the boot.

      (1) Spark Plug nearest firewall: Should be able to get this out with a short extension.

      (2) Middle Spark Plug: Short Extension.

      (3) Spark Plug nearest Rad: Long extension.

      3b. Replace the Spark Plugs on driver's side: Replace each spark plug as you take the old one out. Make sure to set the gap for your Spark Plug at 0.54. Use a gap setter like this one: (Sorry phone cam is not really good) Coat each Spark Plug threads with 3-in-1 oil or anti-sieze. (I used liquid wrench) Torque to 15#

      [​IMG]

      Don't over torque the Spark Plugs or cross thread them. If you do either it could mess up the head. Make sure you that you have the correct Spark Plug wire
      replacement. The connector in the boot will click when full contact is made with the sp.[​IMG]



      4. SP's removal and replacement on passenger's side: These will be a heck of a lot harder but still doable. Do the middle one and the one nearest the rad first. I recommend you don't use extensions on either of these. With these two you are going to have to feel your way to get them out. My dad and I used a crate to get high enough up to reach in to get 'em and both of us are at least 6'.

      [​IMG]

      Replacing the SP next to the firewall.

      OPTION 1

      Now for the hard part. You are going to have to jack the car up to get under it and reach up through the hole in the wheel well to undo the boot and replace the frickin' thing. Usually one person on top with a flashlight and another underneath should be able to do this. Make sure you let the engine cool for a while because you and your buddy will be getting your hands right next to the exhaust manifold.:eek:

      Squirm under the front passenger wheel and place your boards under the shock absorber and set the Ex jack on those boards. Make sure you have the connector piece for the jack to raise it up. It is located right on top of the radiator housing. Raise the jack up till it hits the shock absorber and adjust to make sure it doesn't slip. Now continue to raise it all the way.

      When it is up all the way take your jack stand and put it under the frame. This is to protect you in case the Ex jack fails. Now crawl under the passenger side of the engine compartment. There should be a gap in the wheel well between the well and and the frame. You should be able to reach in there and get the boot off the Spark Plug. Your friend up top should be able to guide you.

      You will have to use an extension on this Spark Plug and you will have to take it off from the bottom. Smaller hands are better for this job. Make sure your buddy guides you all the way. Once the stupid thing is out put the new one and tighten it. Your buddy may have to tighten it once you get the socket on the Spark Plug.

      OPTION 2 (gsmaclean)
      Pull the RF wheel well liner out (a few screws, then pull the plastic liner out) it gives you a lot better access to the plug.

      OPTION 3 (TedJ)

      Remove the passenger side tire


      OPTION 4: The Diehard Way (Four0Sport)
      Magnetic socket and wobble extension from the top.


      6. Take your Ex for a test drive. If it starts to sputter and die under higher speeds then you may have not set the gaps right on the Spark Plugs. If this occurs...redo it all tomorrow. :D


      Hope this helps. My plugs and wires had not been replaced in some time (I purchased it this way) so my plugs and wires looked and were really, really bad.
      [​IMG]
       
      Last edited: May 2, 2010
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    3. beetlebz

      beetlebz New Member

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      hey yo, good write up! Just to add, the spark plug nearest the firewall on the passenger side is actually pretty easy to get to from the wheel well if you just turn the wheel all the way to the right (i think it was). Didnt have to jack it up or anything :)

      I did not bother removing the air intake hose, but thats not a terrible idea! Ill definitely try that next tune-up.
       
    4. MrQ

      MrQ Take the Bull by the Horns Moderator Emeritus

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      Thanks man,

      My dad and I did the jack-up and it worked well...though I wish for goodness sake's we would get a better jack than that crappy oem Ford one. It takes ten minutes to get it to fully jack up the Ex!!

      Back to the point, basically jacking it allowed for easier access to the spark plug as well as the ability to see it. I am definitely not discounting though that there is a better way to do it.

      Also removing the air-intake hose let in more light to the spark plug area and made it all the less crowded.
       
    5. Blacksheep Josh

      Blacksheep Josh Slinky+Escalator=Fun

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      The upper radiator hose, the one you're pointing to that goes from the radiator to engine, does not need to be removed. If you do this on a cool engine, it makes no difference. I've changed the spark plugs on about 3-4 first generations, and this hose has never been a problem. I would think you're asking for more trouble if you remove it, you'll have to make sure you catch the coolant in this hose, and then when you reinstall, you run the risk of damaging it if not done correctly. You also have to burp the system then. Why go through all of that? Do it when the engine has cooled overnight, or at least for a few hours, and you'll be fine.
       
    6. beetlebz

      beetlebz New Member

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      Ooooh I was just thinking the air intake hose, didnt realize you meant the radiator hose too. I hate changing coolant lines, its a PITA imho. My engine was red hot when I did mine, I just let it sit for a couple hours and it was tolerable, though id much rather wait till it was cool lol
       
    7. beetlebz

      beetlebz New Member

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      Oh! just as a side note RE: that passenger side spark plug in the back... apparently MrQ, you and I are smarter than the ford guy at my dealership. Before I owned the truck the original owner took it in every 2-3k like clockwork for service. When I got around to changing the plugs after I bought the truck, that one spark plug on he passenger side nearest the firewall was a different plug and wire than all the rest LOL the never figured it out!
       
    8. MrQ

      MrQ Take the Bull by the Horns Moderator Emeritus

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      You are right. My bad.
       
    9. Hitchhikingmike

      Hitchhikingmike Well-Known Member

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      Hey great write up Mr. Q!

      On another note, I don't know about the earlier explorers, but I do know that the 3gen 4.0's have aluminum engine heads. If you have aluminum heads like I do don't torque the spark plugs while the engine is warm, the aluminum can be playable while hot.

      Here is a trick I like to use when getting my plugs initially threaded before I tighten them down. I like to take a piece of 1/4" rubber tube and stick it on the end of the plug as an extension to help me get it in the hole. It is very hard to strip your threads this way if you get it on wrong, the tube will slip on the plug if you the plug is not threaded in the head the right way. Once they plug is threaded right I just pull the hose off and snug it down with my torque wrench.

      I U-joint on the plug socket is also convent.
       
      Last edited: October 19, 2008
    10. Four0Sport

      Four0Sport Elite Explorer

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      good write up, welcome to the site.
       
    11. gsmaclean

      gsmaclean Active Member

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      A couple more hints:

      - If you pull the RF wheel well liner out (a few screws, then pull the plastic liner out) it gives you a lot better access to the plug.

      - If you have an air compressor, after you pull the boot off the plug but before you remove the plug, blow out the plug area. This will blow out any rust, dirt or other crud, so that it doesn't fall into the cylinder when you pull the plug out.
       
    12. redrockexplorer

      redrockexplorer New Member

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      I changed my right rear spark plug pretty easy by using the spark plug socket with the hex head on it with a wrench.
       
    13. Four0Sport

      Four0Sport Elite Explorer

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      wobble extension and magnetic socket. thats all ive needed to change plugs on my 4.0 and 5.0
       
    14. wishiwerefishn

      wishiwerefishn New Member

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      a lot of trouble for not???

      all i do to change that b#tch is use a hex head spark plug socket (most of them are like that anyway) then use a wrench to turn it and break it loose, then turn it by hand( only a few turns), remove the socket, turn plug by hand until it comes out. then reverse procedure to put in new one. takes only about five minutes to do :eek::salute:
       
    15. Blacksheep Josh

      Blacksheep Josh Slinky+Escalator=Fun

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      For the Passenger side spark plug that's in the very back, I usually just reach down there, put the socket on first, then attach the rachet and remove it. I usually do this FIRST cause it's the hardest, but it's maybe 5 minutes of fiddling with it to replace it, the rest of them take about 15 minutes between removing them, spacing the new ones, and reinstalling them...

      It's about time for new plugs and wires, it was spittin yesterday at times...
       
    16. fubar_mdw

      fubar_mdw New Member

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      This is a great write up.
      On both the X's i have owned i never removed anything just went in
      and replaced them (busted knuckles and bleeding fingers later)
      big pain though.
       
    17. pugsy

      pugsy Active Member

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      The 15 min. is assuming they've been changed at regular intervals. If you have an engine where someone failed to change them...you will have a difficult time doing them in 15 days...let alone mintues!!

      The first two on the drivers side broke on mine as they're prolly originals - had a helluva time removing them, but manged to do it with an easy out and not getting any debris in the cylinders.

      So there's no way I was going to tackle the passenger side bank. They're stayin in there till they fail!!
       
    18. kozak

      kozak New Member

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      I agree, I have never removed anything or jacked up the vehicle to change spark plugs. Good write up though.
       
    19. Blacksheep Josh

      Blacksheep Josh Slinky+Escalator=Fun

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      The spark plugs on my Explorer had only been changed twice in the last 15 years. I was the third person to change them, so I know what stuck spark plugs are like. I never broke any off, but I went slow with them, using gradual pressure until the broke loose. When I reinstall spark plugs, I make sure they're nice and snug and not going to back out, but I don't go crazy on the torque.
       
    20. smbracing

      smbracing Member

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      Same on my '94, that particular plug had at least a .125" gap LOL
      I've changed plugs on tons of 4.0 EX's, and the 2.9 on my B2 was just as bad, but the worst was a 4.0 2wd ranger, the extra suspension height makes it much easier to access the back passenger's plug. That made a good 30 minute job though a 45 minute job :thumbsup:
       
    21. smbracing

      smbracing Member

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      Same on my '94, that particular plug had at least a .125" gap LOL
      I've changed plugs on tons of 4.0 EX's, and the 2.9 on my B2 was just as bad, but the worst was a 4.0 2wd ranger, the extra suspension height on the 4wd models makes it much easier to access the back passenger's plug. That made a good 30 minute job though a 45 minute job :thumbsup:
       
    22. pugsy

      pugsy Active Member

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      Does it snow where you live?
      My broken ones were rusted to the head and the hex on the plug was so rusted that it wouldn't fit the socket properly anymore...assuming the rest are the same... prolly why no ones ever changed them! lol Don't blame them.
       
    23. mckrooz

      mckrooz New Member

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      Thanks for this. Good move on removing the wheel to get to that passenger side plug. It was a cinch after that.
       
    24. TedJ

      TedJ Active Member

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      Removing the passenger side tire is much easier than going from the top... You can reach right in there. I thought the explorer was a pain till I did an Aerostar... same engine but its basically inside the dashboard. You would think they would move the coil pack but its still in the same explorer location.. :rolleyes:
       
    25. mora20164

      mora20164 New Member

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      Changing Passenger Firewall Sparkplug

      I changed the spark plugs this weekend. I didn't have too much trouble changing this Pain in the ass "SP". What i did was Move the Steering wheel all the way left. This provided enough space underneath the wheel well to reach in pull the wire and change the plug. No jacking up the car and didn't have to take tire off.
       
    26. Dean403

      Dean403 New Member

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      Great write up! Very helpful.

      A few additional thoughts....

      1. Jacking the right side is unnecessary, but helpful I think. Gives you more room to wiggle about.

      2. DO NOT under any circumstance forget the anti-seize unless you have no intention of ever removing the plugs. Last owner of my truck changed the plugs (even the rear right) but skipped the anti-seize. Had to use a reefer bar on the socket wrench to get the damn things turning. The one at the rear right was special, and I ended up breaking it in two while removing it.

      3. Take a brush or air hose or scraper and remove some of the rust around the plugs before removing them. I had a lot in there - enough that in some cases I couldn't even get the socket in before digging out the rust.

      4. Change the wires with the plugs, especially if you haven't done the plugs in a while or you don't know when the wires were last changed. You'll be happy with the results. Trust me - or search the forum for why.

      5. While we're on the subject of parts, don't trust the parts counter morons to give you the right plugs and wires. Check then double check before you get messy and start opening things up. The guy I dealt with gave me 4 plugs for the Explorer and 2 plugs for a newer Chrysler 4.7. Funnily enough, I actually own a Jeep with that engine, but having just changed the plugs in there I had no use for the new ones. Cue PITA trip back to Canadian Tire to get the right plugs part way through the job

      On a scale of 1-5, plugs is an easy 1. Nothing difficult here, and nothing the novice can't tackle on their own in the garage.
       

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