Injector seals/insulators and o-rings

Posted by kenamond, May 24, 2006
Newbie Forum - Beginner DSM modification questions and discussions. Common, repetitive, and general discussions will get dumped here from other tech forums. Unless you're a Probationary member you shouldn't post threads here.

  1. kenamond

    kenamond DSM Wiseman

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    I have boost leaks at all four of my injectors and (obviously) want to fix them.

    First, I just need to make sure I understand the sealing system of the fuel rail/injectors on my 2g.

    The seal at the bottom of the injector seals the injector to the head (and all four leak quite badly right now and need replaced). Some have referred to these as insulators.

    The o-ring at the top of the injector seals the injector to the fuel rail.

    Also, there are two o-rings at either end of the fuel rail (between the high pressure fuel line flange and rail and between the fuel pressure regulator and the rail).

    Questions:
    1) Can I get these o-rings and seals/insulators at Autozone/Carquest/NAPA? Maybe injector o-rings aren't sold without new injectors. If not, where do you suggest I get them?
    2) Will I actually end up with the correct parts? If not, where do you suggest I get them?
    3) Should I ask for injector seals or injector insulators? Autozone has the throttle body gasket in their computer as a "fuel injector gasket", so who knows if they'll cross reference it correctly.
    4) Is there only one o-ring per injector on the stockers? I know some other larger injectors have 2, and I want to purchase the correct number.
    5) Should I bother replacing the o-rings or am I risking a fuel leak for no good reason? I've never done this, so if I'm safe leaving the old ones in (I have no fuel leaks), that'd save me some time and save me the risk of finding out after I pull the injectors that Autozone gave me the wrong ones.

    Thanks!
    #1
  2. daren_p

    daren_p DSM Wiseman

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    You are correct on all your assumptions. While your in there replacing the insulators (which are common to have to be replaced as they dry up & get hard) might as well do the orings at the same time. Best place is to go to the dealer or a dsm vendor. That way you know your getting the correct parts. The fuel system is one thing you don't want to cheep out on.
    #2
  3. GVR4592

    GVR4592 Proven Member

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    Napa carries them if you can't find them local http://www.machv.com/fuelincomork.html
    They are easy to replace and a boost leak is never a good thing.
    #3
  4. daren_p

    daren_p DSM Wiseman

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    OMG $40 for 12 seals? Normally their about $15 from dsm vendors without the top seals/spacers (just the upper o rings and lower insulators) as the top seals/spacers don't tend to wear out.
    #4
  5. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    As stated, the injector insulators and o-rings are an easy and straight forward project to replace as is the o-rings for the rail feed and return fittings. Also, I would do as suggested, hit the dealer or one of the vendors so you're assured of getting the correct parts.
    #5
  6. GSntncT

    GSntncT Proven Member

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    I've not had one issue from getting them from NAPA myself.
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  7. oldman

    oldman DSM Wiseman

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    Make sure you install them with dielectric grease, especially the top o-ring. Here's a place where you can get them for $15.

    http://www.diamondstarmotorsport.com/maintgaskets.shtml
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  8. kenamond

    kenamond DSM Wiseman

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    Did you have luck with all of these parts (fuel rail o-rings, injector o-rings and insulators)?

    Since we're not talking about a fortune for these parts, I might just try NAPA first, remove the fuel rail tonight to see if everything is correct, and if not, order them online (probably from where oldman recommended). I'll be on vacation for a week without my car, so I can have stuff ship while I'm gone without extra down-time for my car. And I have a truck I can use in the meantime. Sucks not having a dealer closer than 45 minutes away.

    Thanks. Forgot about that part, though I've read it in several of your posts before. I'll do this, but I'm the super curious type; what does it do? Improve heat conduction from the head out of the injectors into the fuel rail? Seems you'd not want it on the insulator if you want to keep heat out of the injectors as much as possible...?

    Thanks again everyone!
    #8
  9. spoold

    spoold Supporting Member

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    To add to this topic, i have two more questions :

    The link given for the seals and o rings, does that kit not come with the insulators?

    Is there a seperate place to get those?

    Also, does anyone know if that kit would fit the OEM EVO 8 injectors as well as our injector/RC injectors?

    thanks!
    #9
  10. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    In this case it helps the assembly slide in easier with less likelihood of twisting or tearing the seals. In a throttle body it helps reduce friction on the shaft seals as well.
    #10
  11. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    1. The seals are the insulators...same thing, different name.

    2. Don't know.
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  12. oldman

    oldman DSM Wiseman

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    Like Jim said it's for lubrication during installation, I use it on most o-ring applications.

    Seals = insulators.

    EVO8 = don't know
    RC = OEM

    edit : Damn you Jim, that's twice today. :thumb:
    #12
  13. kenamond

    kenamond DSM Wiseman

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    So you use dielectric grease instead of a dab of oil because....? Does the oil react with the sealing material adversely?
    #13
  14. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    Oil can cause SOME seal material to break downdry up prematurely, plus it "wipes" away pretty quick. The die electric grease (silicone) is less likely to cause/do this for the seal materials used in our cars, plus it doesn't "wipe" away as easily.
    #14
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  15. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    It's kind of slow at work today.:cool:
    #15
  16. kenamond

    kenamond DSM Wiseman

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    Oh, another (probably stupid) question I forgot to include: To depressurize the fuel system, the tech article and my Haynes manual say to disconnect the plug under the rear seat. I don't fully understand how removing an electrical plug depressurizes a car with the neg battery terminal already disconnected. My uncertainty makes me hesitant about doing this and having fuel spray everywhere when I unbolt the high pressure fuel line flange.
    #16
  17. kenamond

    kenamond DSM Wiseman

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    Okay. That was a bit of a leading question on my part. If oil degrades the insulators, could blowing a turbo and sending oil through your intake cause premature insulator leaks when you slap an upgraded turbo and whatnot on? My car seemed to run great before I blew my T25 (quart-of-oil-in-the-intercooler-in-30-seconds kind of turbo death), so I'd be suprised if the injectors were leaking boost before the turbo died. Might be worth it for people in that situation to know that they are likely to have insulator leaks. Also might be another reason to modify your valve cover breather to trap oil before it gets into the intake pipe. Just a thought.
    #17
  18. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    The only stupid question is the one you DON'T ask.

    The easiest way to depressurize the system is to unhook the plug you're referring to and then fire up the car. It will run for a couple of seconds then die. You're now depressurized. Also another thing that you can do is to put a rag around the connections to catch the little bit of gas that is still in the system so it doesn't create a mess.
    #18
  19. FORMONTOYA

    FORMONTOYA DSM Wiseman

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    The breaking down of seal materials isn't a dramatic thing. It's NOT like a seal will go bad in a month using oil compared to a year using the silicone grease. Just some materials lifespan is decreased using oil as a lubricator.

    The insulators were probably bad and you just didn't notice that part. The insulator are right on the head exposed to a lot of heat and that is what will harden them and then they loose their "sealing" properties.
    #19
  20. oldman

    oldman DSM Wiseman

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    Without getting into what you have read so far, this is how one should relief fuel pressure.

    1. remove your gas cap.

    2. Disconnect the wire harness to the pump.

    3. Turn the car on and let it run until it dies.
    #20
  21. kenamond

    kenamond DSM Wiseman

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    Awesome guys. Thanks again! Now I just have to wait on the mailman for injector insulators/o-rings. The Mitsu dealership couldn't find the high pressure fuel line o-ring in their system (I think he was literally looking at a picture of the assembly by the way he spoke), so I ordered a 2nd FPR o-ring gambling that it'd be the same. Are they the same? I'll probably search for an online vendor and order one just in case (didn't find anything at SBR or ExtremePSI, but I'll look at that link oldman posted).
    #21
  22. Mark4g63t

    Mark4g63t Proven Member

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    WOW has this ever helped me! Thanks Guys
    #22
  23. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    Terribly old thread but since DiamondStarMotorsports is no longer around here is the best seal kit on the market today: Fuel Injector Clinic's Complete DSM Seal Kit for $25 shipped: Complete seal kit for DSM/Evo OEM injectors. (Does not fit FIC/BlueMAX injectors. Order kit SLK 125/6 x4 for FIC injectors.)
    #23
  24. Mark4g63t

    Mark4g63t Proven Member

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    Damn thats Cheap! it was almost $60 from the dealer for just the 4 injector insulators and 3 fuel rail insulators..
    #24
  25. Ghost_GSX

    Ghost_GSX Proven Member

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    Hope I can pick these up locally and not have to wait long.
    The ONE thing I forgot to order after making like 20 different orders.
    But one thing I will not skip out on.
    #25

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