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Stuck fuel cap 512 bbi

Discussion in 'Boxers/TR/M' started by pshoejberg, Jun 11, 2020.

  1. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Peter H
    I'm in trouble and hope some of the bbi owners can help me . The fuel cap on my 512 bbi is appearing stuck. I've assume I have unlocked it and the cap can now make approximately one turn left or right before it stops. I have tried to turn it left until it stops and then apply force to unscrew the cap but it doesn't move the slightest. Am I doing something wrong or are the cap known for being prone to go stuck? What is the cure? Any ideas or comments much appreciated.

    Best, Peter


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  2. 4right

    4right Formula 3
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    Sounds like it is still potentially locked. Did you try unlocking it with the key?
     
  3. Ludwig

    Ludwig Formula Junior
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    Mar 27, 2006
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  4. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Jan 11, 2001
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    That was my first thought, too: "what lock?" ;) -- but the BB512i SPC does show that two types of gas caps are possible (one with lock, one without lock).
     
  5. 4right

    4right Formula 3
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    The yellow section manoeuvres to the side revealing the lock.
     
  6. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Yes the cap is with a lock. I believe it works like this: If the cap is locked it free spins and if unlocked it should be able to turn left and unscrew the cap. This is new to me, thats why i’m not 100% sure of the correct funktion. best Peter
     
  7. 4right

    4right Formula 3
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    Do you have the owners manual available? I would reference the proper operation of the lock there.
     
  8. MerlinTech

    MerlinTech Formula Junior
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    Mar 5, 2010
    512
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    Wade Williams
    The locking cap does free spin in the locked position. If it stops turning, it is unlocked but stuck. You can take the rubber connection hose off and remove the filler tube with the cap. That will allow you access to the back side and get some penetrate lube to the threads and possible break it loose.
     
  9. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Thanks for input to every one. Next step will be to follows Wade's suggestion; remove the filler tube, fill it with penetrating oil and try to loosen the stuck thread while having the tube firmly supported in a vices.

    Best, Peter
     
  10. Drew Altemara

    Drew Altemara Formula 3

    Feb 11, 2002
    1,342
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    Mine has gotten stuck a couple of times. Its difficult to get your hand in there. I have a non-locking cap.

    I've managed to tap/graze it in the counter clockwise position with a rubber hammer a couple of times to the point where I can open it by hand.

    I don't think a few gentle taps would hurt if you are careful.

    Might want to give it a try,

    Drew
     
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  11. 360+Volt=Prius

    360+Volt=Prius Formula 3

    Sep 1, 2013
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  12. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Thanks for the hints. I love the strap type oil filter wrench and will pursue that solution. I have the claw type wrench in my workshop but I’m afraid it will make marks in the cap or even worse crush it.

    best, Peter
     
  13. dwhite

    dwhite F1 Rookie

    You have to be careful when screwing it on or you can crossthread the cap. It may have gotten a bit of corrosion built up as its an alloy filler neck and a steel cap. As has been said try getting some penetrating oil under the cap or just use something- like a rubber stap from HF - and twist it hard. They do get tight and I have experienced a time when it felt like way more force was necessary to remove it, but it does eventually spin free.

    I'm sure it will come right off with the right tool/technique. Good luck.
     
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  14. 2dinos

    2dinos Formula 3

    Jan 13, 2007
    2,410
    Yup! Had that happen to me. Kind of embarrassing at gas station. Not the key as the lock function just lets cap spin. I think it might be the gas effect on rubber seal? It just gets glued on there and don't recall making it that tight.

    Station attendant offered to try so I felt it safe to let him (a Sword-in-the-Stone moment) - Nope!. Went home and used the rubber strap wrench. EZ! Now I'm very careful on tightening.
     
  15. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    romano schwabel
    put a little oil on the gasket sometimes
     
  16. rovexienus

    rovexienus Formula Junior
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    Jun 10, 2010
    477
    Sainte Colombe, France (near Lyon)
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    Jean-Michel Savary
    Hi Peter, my fuel cap was kind of stuck once and luckily decided to come loose.

    However I was ready for the next step as already suggested by Drew, refer to the picture: while operator 1 applies anti-clockwise torque on the cap, operator 2 repeatedly taps gently on the lock with a rubber hammer through a 10mm bolt, the vibrations will hopefully starts a micro movement of the thread and allow the cap to open. Could be done with just one operator if hammering directly on the cap (without the bolt). Not easy to implement as there is not a lot of space in the area.

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  17. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Mission completed! The cap is now removed without damaging the fragile and no longer available fuel cap or filler pipe. I used the following procedure: Removed the fuel filler pipe with the stuck cap and soaked the threads in WD40 over the night. This morning I bought a oil filter wrench and modified it with a rubber liner to avoid scratching the cap. I mounted the fuel filler in a vise and carefully heated the the cap with a electric heat gun and unscrewed the cap using the oil filter wrench and very little force. The threads must have been bone dry and it doesn't help that there is new plating on both cap and pipe. I added some anti-seize before the cap was re-installed. Thanks a lot to all for great help and inspiration.

    Best, Peter

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  18. BigTex

    BigTex Seven Time F1 World Champ
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    Dec 6, 2002
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    I would totally NOT use that locking style and go with our 308 style cap.

    There's a later version shown in this thread but the original ones are a metal cap with outer plastic grab ring.
    Unobtainium Supply can rebuild the outer ring making a fresh one.

    Like someone is stealing gas at $1.65 a gallon??

    :D :D :D
     
  19. rovexienus

    rovexienus Formula Junior
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    Jun 10, 2010
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    Jean-Michel Savary
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  20. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    I wish.....In my part of the world it's closer to $6 a gallon, that kind a justify the cap. Also the cap is original to the car and it looks so damn cool....;)

    Best, Peter
     
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