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How to: NP 3.8L Spark Plugs

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  • icysyrup
    Valued Member
    • Jun 2007
    • 747
    • USA

    How to: NP 3.8L Spark Plugs

    It was time for a plug change as I was getting a random misfire error code. Its not that bad of a process just longer than most other vehicles because you have to take the intake manifold off and everything else that attaches to it. This is the second time I have done mine and it took me 6hrs the first time and 4 hours this time. So its not that hard of a job that can be accomplished on weekend with a few simple tools to save yourself a bunch of money in labor that some mechanic would charge.


    Total time :4-6 hrs
    Tools you will need.

    8mm socket
    10mm socket
    12mm socket

    Ratchet
    Extensions
    Pliers

    Heres a pic of the engine bay




    First off you will need to remove all the intake and airbox assembly so that you have more room to work. Its a pretty straightforwards dissassembly



    Once you have the Airbox and stuff out you need to start taking stuff off the manifold itself. I started on the side that the Throttle body is on and worked my way around.

    Most all are 10mm bolts that attach stuff to the manifold. There is a coolant line that goes to the throttle body on the back side closest to the firewall. You will know it when you remove it. Just stick it up high against the firewall and it will stop leaking.



    To keep stuff organized I would remove the bolt and then put the bolt back in its spot when the item is taken off. That way I dont have a pile of bolts laying around wondering which spot they go in.

    Most all those connections are plugs that need to be disconnected. However there was one that I had a hard time figuring out how to unplug. So to save busting it and a lot of frustration I just got a 8mm socket and took the two bolts out and removed the sensor entirely. Here is a pic of the sensor I am talking about for reference.



    On the front it is not necessary but will free up more space and allow for a little less clutter if you disconnect one of the fuel lines and tuck it up out of the way. It is not a high pressure line so dont worry about it blowing fuel everywhere. I threaded a bolt into the tube to plug it up to stop leakage.



    There are 2 bolts underneath the throttle body that support the manifold on that side. They are 12mm. Also remove the 2 - 12mm bolts that hold the Exhaust return line that is there as well and bolts to the bottom the throttle body.




    Once you have everything off the manifold it is time to take the 6 main bolts out. They are 12 mm and you will need an extension on the ratchet as well. When I removed them I laid them out in order beside each other so that I wouldnt get them messed up, as they are of various lengths and it just makes reassembly easier. Also there is a lock washer on each one,...dont worry about it falling off because it wont. The threads at the bottom of the bolt will stop it.

    You will see little indents in the manifold looking down from the top where each bolt will be between the intake runners.



    There are 7 total I think starting with one at the very front and then one all the way in the very back. This one in the back can be a bit stubborn so if you can get the right ratchet/extension combo it makes it much easier. My ratchet swiveled allowing me to do it easily. Here is a picture of the bolt on the back that I am talking about.






    Once everything is removed you will be able to take the Intake Plenum off. This is where you will see if you have removed everything from it or not.
    Set it aside gently as to not damage the lower mounting portion.
    I stuffed some shop towels down the intake runners to stop any foreign debris from getting in there possibly. Now that everything is off you can see the access to the spark plugs is much much easier.





    Here is the Ignition coils on the opposite side. The spark plugs are underneath them.There are three total





    Two bolts to remove them and they come up just like the spark plug boots did on the other side. Make sure when checking them to do each plug individually and not take all the wires and plugs out at once becuase you will be very confused if you do that wondering What goes Where. If you do each wire and plug together and then replace with new ones and reassemble that one before you move on to to the next you will save yourself a lot of stress.

    While I had the time I took each Plug wire and tested the resistance on them to make sure they were still good. Then I tested the Ignition coils resistance as well. Here are the specs on them.





    The gap needs to be set as well on your new plugs before installation and then just reassemble everything in reverse order. The intake plenum can be a little finiky to get lined up with the gasket and the bolts. I started at the front and worked my way back with the bolts. Also here is the breakway pic with all the correct torques on the bolts for reassembly.



    Hope this helps someone save a little money and please post up any errors that you may find so that it may be corrected.

    Regards,
    Phil
    03 NP, 34" tires, Fully skiplated, Custom rocksliders, custom winch mount, OME HD springs/shocks, and Aeroflow exhaust, Locked Front and Rear.

    Happiness is like peeing your pants, everyone can see it, but only you can feel the warmth.
  • Ridgeback
    Member
    • Jan 2008
    • 174
    • Sydney

    #2
    Thats awesome mate, I don't have an NP but I like it! In particular I like where the resistance values are annotated 'in situ'.
    Home Base Sydney, NM GLS 3.5L, LPG, Dual Batt, Milford Barrier, Rhinos, Lovells 50mm with Bilsteins.

    Comment

    • marcthelegend
      Valued Member
      • Sep 2008
      • 1172
      • Gosnells, WA

      #3
      Icy, great write up! will be tackling this one soon, anything else you can see worth doing while the motor is apart, thinking of somehow cleaning the inside of the intake plenum? and just generally tidying things up.

      Cheers

      Marc
      05 NP GLX 3.8 Auto. 2" Lovell/Bilstein Lift, ARB Deluxe Winch Bar, Granke mk3 12,000lbs winch, Uniden UH015sx, HID spotties, Roof mounted light bar, Work lights, Upgraded stereo, Tinting, 2.5t tow, dual battery setup (homemade), Radar Renegade tyres, wired up dummy lights, Bushskinz Sump/Intercooler plates, home-made diff breathers (front and back) and a cheap ebay snorkel.

      To-do:
      brake upgrade, oil seals (again!!)

      Comment

      • sharkcaver
        "2000"+ Valued Contributor
        • May 2009
        • 6270
        • Perth

        #4
        OMG, glad ive got a DI-d. Top writeup, I'm sure others will find it a real help. When I find a good posting such as this, I usually print it as a pdf and save for future reference.

        Shane.
        MY16 NX GLX5 with just a few bits added. MY14 D-max spacecab, also with a few bits added.

        My Journeys

        Comment

        • Pete
          Valued Member
          • Jan 2010
          • 947
          • Mornington Peninsula, Vic

          #5
          Great guide. Amm attacking it this weekend. I was gonna replace plugs and leads. I wont have to parts once i start so i need to buy everything during the week.

          Are the coils normally replaced at intervals or only when an issue is detected? Do i just buy plugs and leads (i will get genuine platinum)?

          Ta

          Comment

          • peejay68au
            Valued Member
            • Jul 2007
            • 1009
            • nsw

            #6
            Originally posted by sharkcaver View Post
            OMG, glad ive got a DI-d.
            Makes me not want a petrol jabber period. I like simple. Simple suits a simple man.
            ---------------------------------------------------------------------------------------------------------
            It's not what you look at that matters, it's what you see.

            Henry David Thoreau

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

            Comment

            • ngwagon
              Valued Member
              • Nov 2009
              • 1025
              • mt evelyn

              #7
              wow thats a lot to remove just to get to the plugs.. to pay someone to do that would be a small fortune for labour and parts..

              Comment

              • Pete
                Valued Member
                • Jan 2010
                • 947
                • Mornington Peninsula, Vic

                #8
                I got quoted 280 in labour...

                Comment

                • Pete
                  Valued Member
                  • Jan 2010
                  • 947
                  • Mornington Peninsula, Vic

                  #9
                  Good tips to get the manifold off in one piece. Took me 2.5hrs from start to startup. Had one plug that was super tight, i soaked it in rp7 and took my time.

                  Broke a coolant moulded hose so i replaced with a longer non moulded...otherwise its very straight forward...

                  Why are some of the plastic electrical connectors using that little wire spring...WHY!?!?!?

                  Comment

                  • Goodsy
                    Who ya gunna call....
                    • Dec 2010
                    • 7598
                    • Hervey Bay

                    #10
                    Ok I'll invite you around when I get around to doing mine Pete.
                    .Previously an NP GLX 3.8 auto RIP
                    NS VRX DiD auto. RIP.

                    Comment

                    • Pete
                      Valued Member
                      • Jan 2010
                      • 947
                      • Mornington Peninsula, Vic

                      #11
                      Mine is the 3.5 and its slightly different to the pics of the 3.8 but the big tip is to take the intake off in one piece. There is 10 or 12 things plugged into it and that's it. You follow the guide and you will be fine...if you get stuck i drink anything

                      Comment

                      • Goodsy
                        Who ya gunna call....
                        • Dec 2010
                        • 7598
                        • Hervey Bay

                        #12
                        Originally posted by Pete View Post
                        You follow the guide and you will be fine...if you get stuck i drink anything
                        Water it is.
                        .Previously an NP GLX 3.8 auto RIP
                        NS VRX DiD auto. RIP.

                        Comment

                        • Goodsy
                          Who ya gunna call....
                          • Dec 2010
                          • 7598
                          • Hervey Bay

                          #13
                          Great post and I have saved it. Only took 5 months to get around to changing them.

                          Just an update to the tool list.

                          Must be a 3/8 socket set. A 1/2 is to large to reach manifold bolts.

                          And I have a lot more wires than you.
                          Last edited by Goodsy; 16-10-11, 11:25 AM.
                          .Previously an NP GLX 3.8 auto RIP
                          NS VRX DiD auto. RIP.

                          Comment

                          • saffer
                            Member
                            • Jan 2011
                            • 163
                            • Waikiki, WA

                            #14
                            Just a quick question for the guys out there that has done this.
                            When you disconnect the coolant hoses from the throttle body, do you need to flush the coolant system or something to prevent air lock/bubble? Just want to make sure as I have cooked a motor before by having a air bubble in my cooling system.
                            Thanks in advance
                            2009 NT X SWB V6 - Opposite Lock bar, VRS winch,MM Tow Bar, Uniden UH7760NB, Lightforce Striker 50wHID, ARB awning, Rhino Racks, Bridgestone D697's, Billstein/Lovell, Skinned up + Rocksliders, Redarc TowPro, Safari snorkel, ARB on-board air, Powerflow exhaust

                            Towing: 2015 Jayco Eagle Outback

                            Comment

                            • QldGary
                              Junior Member
                              • Dec 2017
                              • 5
                              • Sunshine Coast

                              #15
                              3.8L NP Pajero spark plug change

                              I really need to do this and cant access the photos!
                              Anyone copy them and can share?
                              I've contacted Phil but no answer yet.
                              The text is great but the pictures tell a thousand words.
                              Cheers,
                              Gary

                              Comment

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