Disabling ignition system

Discussion in 'Electronics' started by dredd32, May 6, 2014.

  1. dredd32

    dredd32 Hardcore MB Enthusiast

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    Does anyone know how to disable the ignition system on a c32 amg??

    I am replacing the crankshaft pulley but I don't have the pulley holder to do the job..I've seen that if you disable the ignition system then fit the ratchet and brace it,turn the car over it will release the bolt holding the CS pulley without starting the engine...

    So does anyone know how to disable it and has anybody used this method??

    Thanks
     
  2. Ted

    Ted MB Club Veteran

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    Ermm.... Turn the ignition off and remove the key?
     
  3. OP
    OP
    dredd32

    dredd32 Hardcore MB Enthusiast

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    Ha ha,not exactly the answer I was looking for,but amusing...
     
  4. markmifsud

    markmifsud Hardcore MB Enthusiast

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    He wants to turn the engine over without fear of it starting. Maybe disconnect the power to the fuel pump and run it dry? Always the risk of some residual fuel kicking over a few turns though
     
  5. E270 Owner

    E270 Owner Hardcore MB Enthusiast

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    Let someone do the work who has the correct tools and knows what they are doing !!
     
  6. OP
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    dredd32

    dredd32 Hardcore MB Enthusiast

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    I'll look into that but I'd feel a little safer if I disabled the starter itself.
     
  7. OP
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    dredd32

    dredd32 Hardcore MB Enthusiast

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    I think I'm up to the job just need to find a way to disable the starter system.. Alternatively if you have the tool I'd gladly borrow it:D
     
  8. Stratman

    Stratman Hardcore MB Enthusiast

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    If you disable the starter, how will the engine turn over?
     
  9. Sp!ke

    Sp!ke Administrator Staff Member

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    Edit

    Just read it again and can see what you are doing.

    Cant you just leave it in gear and undo the bolt?
     
    Last edited: May 6, 2014
  10. Auto-mobile

    Auto-mobile Hardcore MB Enthusiast

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    Going by your comments you really need to take it to someone with the proper tool/knowledge as e270 owner stated.
     
    Last edited: May 6, 2014
  11. OP
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    dredd32

    dredd32 Hardcore MB Enthusiast

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    If I disconnect the battery the car won't turnover..I need it to turnover but not start so as to loosen the bolt on the pulley
     
  12. OP
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    dredd32

    dredd32 Hardcore MB Enthusiast

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    I understand what you are saying. It is a fairly simple job to do with the correct tools..without them it takes a little longer..but it's still doable:thumb:
     
  13. carat 3.6

    carat 3.6 Hardcore MB Enthusiast

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    The problem with doing what your thinking of, is that the breaker bar needs to be jammed against a chassis rail or similar. Not sure if you'll have the room to do that, and you wont be able to keep hold of it by hand.

    If you do try it, disable the fuel pump relay as said above. That is the safest thing to do.
     
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  14. OP
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    dredd32

    dredd32 Hardcore MB Enthusiast

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    I'm not sure TBH.

    From what I gather ,disconnecting the switch stops the car from starting therefore just loosening the bolt. With it in gear there's a chance you won't shut the engine off quick enough...I'm not sure where the ratchet will end up but I doubt it would be pretty:eek:
     
  15. fast28

    fast28 Active Member

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    I gather you are talking about using a tool similar to this...

    [​IMG]

    To stop the engine firing simply disconnect the crank sensor harness plug, without a crank signal the fuel injection will be disabled. It may also be a good idea to unplug the fuel pump relay in the fuse box too.
    Never seen this tool used but a few good cranks on the starter should loosen it. Other way is to use the park interlock that locks the crank then it would be a case of a socket on a breaker bar with a metal pipe extension to get the necessary torque to break the bolt loose.
     
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  16. miro

    miro Hardcore MB Enthusiast

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    Have tried this on many cars and it never worked once. All it did was make the tool wedge itself in a way that induces fear or loathing.

    Impact tools have a pulse which reaches well over 100nM of torque. You will find that the dry cranking engine has the same amount of power as the starter motor. Which is almost nothing.

    Then take into account that you must attach the bolt afterwards.

    The only hope you have is to wedge the old fan belt into the pulley but that is for seasoned tradespeople with a deft hand.

    A pulley holder and a torque wrench is your only hope as I am aware of at least 3 instances where your method was used and the crank pulley became the additional sound when it detached from the main shaft, flew all over the engine bay or dented the hood or fell out onto the road at highway speed ... since attachment is harder than breaking things apart.

    You may need a new bolt also. Sometimes there are single use bolts and require a "stretch" once they are torqued. If you dont know how to stretch a high tensile bolt ... ask yourself which of the above problems you want to experience first hand.
     
    Last edited: May 7, 2014
  17. miro

    miro Hardcore MB Enthusiast

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    Doable .... not really. The engine wont run in reverse to tighten the bolt.
     
  18. OP
    OP
    dredd32

    dredd32 Hardcore MB Enthusiast

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    Yep fast28,that's the tool to use...

    Yes milo,I'm leaning towards the pulley bar and ratchet,am just waiting on a call.

    The pulley comes with a bolt and hopefully will have it by the end of the week. Should then get it done this weekend. Will let you know how it goes...
     
  19. Neil Mackay

    Neil Mackay Hardcore MB Enthusiast

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    Replacement standard crank pulley Elvin or are you putting a modded one on?
     
  20. OP
    OP
    dredd32

    dredd32 Hardcore MB Enthusiast

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    Standard pulley Neil. No more performance mods for me:(
     

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