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246GT Ignition Switch Question

Discussion in 'Technical Q&A' started by jselevan, Jan 22, 2004.

  1. jselevan

    jselevan Formula 3
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    Nov 2, 2003
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    For the past 25 years, or so, I have noticed that on occasion my starter continues cranking even after I turn off the key. This, of course, is most noticeable when the engine does not start first time and I turn the key to the off position to retry. The starter continues to crank. I can take the key out of the ignition lock, place it in my pocket, walk into the house, make toast and coffee, come back, and the starter is still struggling.

    I have removed the starter on numerous occasions during these past 25 years to have the solenoid rebuilt, thinking it was the culprit. However, I am beginning to suspect something else.

    Question: Have others experienced this? Is there a design flaw in the ignition switch itself that maintains contact even after I turn the ignition off? Can I replace the ignition switch without purchasing the entire anti-theft locking system (which costs more than the car is worth).

    Thanks for your help.

    Jim S.
     
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  3. Motob

    Motob Formula 3
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    Nov 11, 2003
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    Brian Brown
    The problem is not do to a faulty ignition switch. I had the same situation on a 206gt. If you turned the key to the crank position and the car failed to start, the starter would just kept cranking away until the battery cable was disconnected.

    I removed the trigger wire (terminal 50) at the starter solenoid while it was in failure mode and it just kept cranking away, this ruled out any problem with the ignition switch.

    I removed the starter and bench tested it, it worked fine every time. I replaced the solenoid, thinking that it was sticking under load. Upon installation, the same problem happened.

    I figured that the drive pinion was sticking in the ring gear, causing the solenoid to stay engaged, and would only stop once the engine started and pushed the pinion back.

    Out came the starter, replaced the drive/pinion. Reinstall the starter, and it still has the same problem. This is getting a little frustrating!

    I talked to a starter rebuilder that does a lot of Ferrari stuff. She had experienced the same problem, and it is due to the drive/pinion sticking in the flywheel ring gear. The replacement drives are the cause, some work and some don't. She installed a original used drive, and voila problem is solved.

    Hope this helps!
    Sincerely,
    Brian Brown
     
  4. wax

    wax Four Time F1 World Champ
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    Jul 20, 2003
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    Dirty Harry
    Excellent post/answer on the first shot, Brian. Out of curiosity, what seems to be the primary difference between original and replacement drives?
     
  5. racerboy9

    racerboy9 Formula 3
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    Dennis McCann may have an answer for this problem as he knows Dino's inside out. I seem to remember possibly shimming the starter to gain a little clearance or change the angle of the starter drive to prevent it hanging up on the ring gear (very bad consequences!). I saw one Dino starter that exploded it's armature due to not disengaging the ring gear after the engine started. I would check with him before something awful happens.
     
  6. jselevan

    jselevan Formula 3
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    Brain - great input. However, I did speak with an expert mechanic (former service manager FNA) and he offered that the switches were known to do this. I will contact him with your experience and get a response. He also observed that BMW 2002 used the same ignition switch, and he was able to get the switch from them without having to purchase the entire anti-theft mechanism. In the meantime, I will contact Dennis McCann for his expertise. Thanks.

    Jim S.
     
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  8. jselevan

    jselevan Formula 3
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    Brian - you are a brain, but I meant to address you as Brian. Sorry.

    Jim S.
     
  9. Motob

    Motob Formula 3
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    Thanks for the Kudos. The electrical portion of the ignition switch is the same as BMW 2002, cost is less than $20. It is very easy to replace, only held on by two screws. So you might just replace it and see if you still have the cranking problem.
    Shimming the starter might work, contact Dennis McCann and let us know what his fix is.
    I can't remember what the difference between the original drive and the replacement was, just that putting a used original drive solved the problem.

    Good luck,
    Brian
     
  10. jselevan

    jselevan Formula 3
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    Brian - there are details that I should expand on.

    First, the switch cost $100 from Dennis McCann. The same switch can be purchased at the BMW dealer (2002 ignition switch) for $135. So Dennis's prices are better.

    Second, I spoke with Dennis. He agreed that the switch was the culprit. When I mentioned the discussion about the starter gear and ring gear, he explained that that would be an issue if this is a new starter or ring gear, and the first time you start the car the gears bind together. He may shim the starter to release some of the misalignment. But as this has been happening for many years, he felt that it was the switch, and not the gears. Again, the gear issue is only after service on one or both gears at the initial starter activation.

    Thanks for the lead to Dennis. The switch is in the mail.

    Jim S.
     
  11. Motob

    Motob Formula 3
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    $100! that's some markup, I paid $14 dealer cost for the last BMW ignition switch about a month ago. When you priced the switch at the BMW dealer, did you specify that you wanted only the electrical portion of the switch and not the entire assembly with the key/lock tumbler/steering lock. My guess is that the BMW dealer gave you the price for the entire assembly. If you are interested, I can get the BMW part # for just the switch, but it sounds like you already have one coming from Dennis.

    Brian
     
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  13. jselevan

    jselevan Formula 3
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    Brian - yes, I brought the old switch in, and they matched it against the part number. We discussed the need for only the switch and not the anti-theft locking mechanism. This was at a BMW dealer parts department. Once they looked into the computer and priced the part, I decided to stay with Dennis's switch.

    Thanks.

    Jim S.
     
  14. jselevan

    jselevan Formula 3
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    The saga continues. I replaced the ignition switch with a new one. Starter symptom continues. I turn the car off, place the key in my pocket, and the starter continues to crank.

    The battery is barely able to crank the car each morning. Just about dead. However, the sucker is so well tuned it starts despite sluggish crank. During the day it cranks with vigor. Overnight the battery goes down. No leakage. I believe I have a bad battery.

    Could low voltage somehow prevent the solenoid from switching off? The phantom cranking seems to occur when the battery voltage is down and cranking is sluggish.

    In addition, the charging circuit does not work properly in the morning. Will discharge a few amps for several minutes, and then wakes-up to charge normally. Could this be a consequence of the bad battery?

    Thanks for your help.

    Jim S.
     
  15. racerboy9

    racerboy9 Formula 3
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    I don't see how the starter could keep turning with the key out unless you have a bad solenoid or a chafed wire running from the switch to the solenoid. Somehow the solenoid is being energized. There should be no continuity between the switch wire and the solenoid with the key in the off position. I wonder if you could disconnect the wire at the solenoid and the ignition switch and run a bypass wire to see if the wire in the harness is at fault. Electrical problems are one of my greatest weakness' but that is what I would try.
     
  16. Motob

    Motob Formula 3
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    Nov 11, 2003
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    Jim,
    As I posted before, this is a known problem. The starter staying engaged is due to the drive sticking in the flywheel. The charging system system problem is unrelated to the starter sticking on.

    Brian
     

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