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Help! Spark plug threads GONE!

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  • Help! Spark plug threads GONE!

    So I picked up an 88 M3 yesterday (I will post an intro thread) but as I left work I heard a pop so I pulled back into the shop I found the cyl. 3 spark plug didnt like its home and it would not thread back in. Stripped. Damnit. I ordered some m12x1.25 perma-plugs and will be in next week so I dont get to enjoy my new toy. Will it be possible to repair the threads without taking the head off? I mean I can take the engine apart but if it doesnt have to happen then it will make me very happy. I've already taken the valve cover off to give me room. Also is there a better fix for this problem?

    Thanks for any info given, sucks cause it was the first day owning the car. I will post pics and some more info in another thread, just this is a little aggrovating.
    "A Delicate Balance between Form and Function"



  • #2
    Tooltown (in Kirkland) sells a spark plug thread chaser tool. The top of the threads may be nicked, which may be reaired without too much trouble. I hope the entire length of threads in the aluminum head aren't buggered.

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    • #3
      plug thread repair

      I had to repair the threads in my 540 on a plug. I purchased a kit that is designed specifically for this. You have to tap the head threads oversized and then install the insert with loctite. Then the top of the insert is expanded into the head. It has lasted for 65k miles now so apparently works well.
      I put a dollop of grease into the plug hole to catch the tapping shavings. Then I removed the grease. After that, I used a vacuum and tubing to suck anything I could find inside of the cylinder. Worked out well.

      Hopefully though you can just chase the threads. I would be very thorough in an inspection of the car after this. Sounds like there may well be more issues.

      Good luck, hopefully it can be fixed easily.
      Cheers,
      John
      88M3 henna


      73T100C
      97 540\6-Gone
      2008 MINI Clubman S

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      • #4
        Yeah I might try and chase it first off, but it thread down quiet a ways then just spins freely. It looks like its where it should be depth wise as its spinning. The repair you were talking about are 'permaplugs' or time serts. On your 540 was the plug hole deep and narrow like on the s14? If so it gives me hope.

        The car needs some work that was explained to me by the seller. Shifter bushings (20$), rebuilt driver shaft (200$), rear trailing arm bushings (100$) and exhaust hangers (10$). I get all parts at cost so Im cool there and I do all labor myself.
        "A Delicate Balance between Form and Function"


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        • #5
          540 is not as deep as M3. I did have to use and extension and be VERY delicate as I worked. Definately takes a light touch to get started with threads. Worked like a champ though.
          88M3 henna


          73T100C
          97 540\6-Gone
          2008 MINI Clubman S

          Comment


          • #6
            Ok that gives me some hope, it seems like the threads are somewhat there so the tap should start pretty easy.
            "A Delicate Balance between Form and Function"


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            • #7
              How many miles on your car? Could it be time to do a good head job on it? Even though getting the head off of an S14 is a major PITA, it'd be the best way to get a stripped spark plug hole fixed properly. Also, it sounds as though you're pretty well fixed for a place to do this kind of work.

              Wow -- good idea, JedM3! I was wondering how you kept shavings and stuff from falling into the combustion chamber. Kind of delicate work with the head still on the engine.
              The day ain't over yet....

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              • #8
                Yeah, I was nervous as crap when I started the car. But I tried to be VERY careful to contain all metal. I also cranked the car with the plug out after I was done as well to try and blow anything else out.
                At the high mileage, it would not be a bad idea to pull the head for a rebuild. Or by the one Jake had for sale if he still has it. That is if you have the money to work with.
                88M3 henna


                73T100C
                97 540\6-Gone
                2008 MINI Clubman S

                Comment

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