745 backdoor lock lubrication?

Discussion in 'General Motoring' started by viktor weisshaeupl, Sep 6, 2003.

  1. On my 740 station wagon the back door lock cannot me operated with the key
    because of too much friction apparently between the plastic cylinder and
    hole in which it rotates. Maybe some MoS2-spray liquid hit it when I tried
    to dissolve a sticking screw at the backdoor wiper system. The central
    locking/unlocking works so that is the way I lock and unlock the backdoor
    now. The problem was worse during winter in earlier years I recall but now
    it has become permanent also during the dry and warm season. I have treid to
    lubricate with a teflon based spray from outside whithout effect. Does
    anybody have a solution for the problem besides changing the whole lock?

    Viktor Weisshäupl, Vienna, Austria
     
    viktor weisshaeupl, Sep 6, 2003
    #1
  2. viktor weisshaeupl

    Arnold Perez Guest

    I had the same problem with my 240 Wagon, and the problem may not be in the
    cylinder as you think, but in the sliding mechanism that the cylinder
    operates. You would have to remove the inside panel to gain access to it,
    then remove the screws that hold the latching mechanism in place, disengage
    the link rod and take the whole locking assembly out. The cylinder remains
    in place. Then sand any rust off, grease the heck out of it, re-install and
    enjoy. The whole process took less than 1 hour. Good Luck

    Arnold
     
    Arnold Perez, Sep 6, 2003
    #2
  3. Thanks for the input. What I wonder is, - where does the electric mechanism
    fit in. Is it working on the last members of that chain distant from the
    lock cylinder?

    Viktor
     
    viktor weisshaeupl, Sep 6, 2003
    #3
  4. viktor weisshaeupl

    Arnold Perez Guest

    Hi Viktor, when you take this thing apart you will see that the "cam" that
    rotates when you move the key, also has a rod connected to it, the rod is
    operated by the lock/unlock solenoid (or motor), so that you operate the
    locking mechanism either by the central locking or by the key. In any
    event, if I recall correctly, there was a piston that goes through a hole,
    and the whole thing was rusted shut, after some wire brush and grease, the
    whole thing was as good as new. The locking solenoid was on the right of
    the keylock.

    Arnold
     
    Arnold Perez, Sep 6, 2003
    #4
  5. viktor weisshaeupl

    L.A. Guest

    Try a little K-Y on the backdoor lock ;-)
     
    L.A., Sep 7, 2003
    #5
  6. viktor weisshaeupl

    Arnold Perez Guest

    Hi Viktor, when you take this thing apart you will see that the "cam" that
    rotates when you move the key, also has a rod connected to it, the rod is
    operated by the lock/unlock solenoid (or motor), so that you operate the
    locking mechanism either by the central locking or by the key. In any
    event, if I recall correctly, there was a piston that goes through a hole,
    and the whole thing was rusted shut, after some wire brush and grease, the
    whole thing was as good as new. The locking solenoid was on the right of
    the keylock.

    Arnold
     
    Arnold Perez, Sep 7, 2003
    #6
  7. viktor weisshaeupl

    Mike F Guest

    Those lock cylinders on the 700/900 are very corrosion prone. Chances
    are the only cure will be replacement, or you could just ignore it and
    trust the power lock not to fail. Even if it does fail, you can still
    open the tailgate from the inside, provided the child-proof lock is not
    engaged.
     
    Mike F, Sep 8, 2003
    #7
  8. What is K-Y ? Living in central Europe I don´t know what it is. We have
    sprays containing MoS2 for lubrication of rusted or corroded mechanical
    stuff. Is it something like that?

    BTW it does not feel like rusted mechanics, it really feels like friction
    between the plastic parts of the cylinder which I interprete as possible
    consequence of oil dripping on it by accident.

    Viktor Weisshäupl
     
    Viktor Weisshaeupl, Sep 8, 2003
    #8
  9. viktor weisshaeupl

    Peter Milnes Guest

    K-Y Jelley is a lubricant in medical use (including sexual use). Much better to
    use either WD40 or Duck Oil.

    Cheers, Peter.

    :
    : : > Try a little K-Y on the backdoor lock ;-)
    :
    : What is K-Y ? Living in central Europe I don´t know what it is. We have
    : sprays containing MoS2 for lubrication of rusted or corroded mechanical
    : stuff. Is it something like that?
    :
    : BTW it does not feel like rusted mechanics, it really feels like friction
    : between the plastic parts of the cylinder which I interprete as possible
    : consequence of oil dripping on it by accident.
    :
    : Viktor Weisshäupl
    :
    :
    :
    :
     
    Peter Milnes, Sep 9, 2003
    #9
  10. Which raises the next question - what is WD40? Any hints on the chemistry of
    that stuff?

    Viktor
     
    Viktor Weisshaeupl, Sep 9, 2003
    #10
  11. viktor weisshaeupl

    Peter Milnes Guest

    It is a special lubricant, waterproofer, contact cleaner, etc. that has been in
    use in the UK for many years. It was developed for the Armed Forces as a
    multi-purpose liquid not long after WW2. I used it when I was in the RAF
    servicing V-bombers.

    Cheers, Peter.

    :
    : : > K-Y Jelley is a lubricant in medical use (including sexual use). Much
    : better to
    : > use either WD40 or Duck Oil.
    :
    : Which raises the next question - what is WD40? Any hints on the chemistry of
    : that stuff?
    :
    : Viktor
    :
    :
     
    Peter Milnes, Sep 10, 2003
    #11
  12. viktor weisshaeupl

    Gary Heston Guest

    Most reports indicate it based upon kerosene (which you may know as
    paraffin, a liquid used as lamp and stove fuel). The real formula is
    a trade secret.

    More indepth guessing can be found at:

    http://www.newton.dep.anl.gov/askasci/chem00/chem00165.htm


    Gary
     
    Gary Heston, Sep 10, 2003
    #12
  13. viktor weisshaeupl

    Gary Heston Guest

    [ ... ]

    It first appeared on store shelves in 1958, five years after it was
    invented in 1953--a good bit after WW2. When were you in the RAF?

    WD-40 history:

    http://www/wd-40.com/AboutUs/our_history.html


    Gary
     
    Gary Heston, Sep 10, 2003
    #13
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