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W202 Boot Lock Fix.

Discussion in 'Bodywork, Tyres, Wheels & Trim' started by Dec, Apr 6, 2009.

  1. Dec

    Dec Senior Member

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    It is important that the boot and indeed door lock are working properly.

    The use of remote central locking means keys are seldom used to open the boot. This irregular use of the key in the lock over long periods of time can result in corrosion and seizure of the lock mechanism, this can become a big problem if the central locking or vacuum pump fails and the boot can’t be accessed via the key.

    If the key can’t enter the lock fully then some of the levers are seized or the key you are using is not the correct key for the lock.
    Probably, in 99% of cases, when the key wont turn in the lock there is nothing broken, bent or worn inside the lock, it is just that the mechanism is bone dry and corrosion has built up, adding to the problem, lubrication solves that.

    The condition of the lock in Picture A looks a lot worse than it actually was, lubricating it in the way described in the last picture (P) would have solved the problem, without the need to dismantle the whole unit.

    This boot lock is non-electric on a 1994 C180 = W202 and is Locked/Unlocked by the vacuum pump or by the key.
    After all the components were cleaned up, the only lubricant I used was thick grease, every thing that moves, slides or rotates was given plenty of grease.

    Tools required;
    Work on the kitchen table over an old towel, to catch any small components, springs etc that may be dropped
    Fine sandpaper to wipe the brass levers, don’t over do it, but clean them just enough to allow them to move freely in their slots.
    Sewing needle for clearing out slots.
    1 Spanner or socket, 12mm.
    Needle nose pliers.
    Small screwdrivers.
    WD40
    Thick grease
    Allow yourself plenty of time, not a job to be rushed.
    Pen and paper to keep track of which lever belongs in which slot when dismantling the lock barrel.

    Dec
    Edit, anyone know why these pictures don’t appear?

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    Last edited by a moderator: Apr 6, 2009
  2. dave.robbo

    dave.robbo Senior Member

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    Excellent write up Dec.

    Just wish I'd bothered to take some pics when I did mine today, as the estate boot lock is totally different.
     
  3. anyweb

    anyweb Senior Member

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    excellent and moved to DIY, the pics didnt appear as they all had URL infront and behind them, plus theres a limit of 7 photos per post, i've posted the rest below

    thanks DEC
     
    Last edited: Apr 6, 2009
  4. anyweb

    anyweb Senior Member

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    You have included 9 images in your message. You are limited to using 7 images so plea

    heres the rest of Decs photos


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  5. anyweb

    anyweb Senior Member

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  6. anyweb

    anyweb Senior Member

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    thanks again for this great post Dec,

    can you please clarify what key should be used to open the boot lock, is it the same key that I start the car with, as when I insert that key into the boot it only goes in about 2/3rds the way in and then stops, is that because one or more levers are stuck or something ???
     
  7. television

    television Always remembered RIP

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    It is the same key,,it is just that the tumblers are stuck, These are the little blanking caps available from MB at 50p each that push in to lock, and easy to spray to match the car
     

    Attached Files:

  8. OP
    Dec

    Dec Senior Member

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    The flip out key and the emergency flat key if you have one.
    On mine
    Insert key at 12 o’clock and turn to 10 o’clock will unlock
    or
    Turn key to 2 o’clock will lock
    Key must be turned to 12 o’clock to remove it from lock.

    On some models the key can be turned to 3 o’clock, this is something to do with denying access to the boot if you are sitting in traffic with doors open…no one can open the boot and steal the contents.

    You have one or two levers stuck, the key should go in almost exactly 1.5 inches.
    Flood the lock with WD40, put the straw right into the lock and give it at least a 3 second burst of oil, repeat and wiggle the key in and out of lock, also try a ladies hairpin, opened it out and work it all the way into the lock, wiggling it up and down as you go.

    Don’t use any force with pliers, hand force only.
    Also it might just be ice, try heating the key.

    Dec
     
  9. Wittybebop

    Wittybebop New Registration

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    That's a great photo writeup, I've just done one today and it was a lot worse than the one pictured, it was absolutely solid.
    Just to add my 2p worth, when you come to put in the retaining ring "circlips ring" as described, holding the lock housing carefully in a vice a 13mm deep socket on a small extension is ideal for pushing the lock down against the springs and fitting the ring is then a doddle, it can be done on your own but with someone else pressing it down it takes 10-15 seconds.

    Hope this helps some more.
     
  10. television

    television Always remembered RIP

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    Hello, thank you and welcome :D
     
  11. OP
    Dec

    Dec Senior Member

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    That’s good advice thanks, never crossed my mind to use a vice…no wonder I can’t get into Mensa!

    Dec
     
  12. jools182

    jools182 Senior Member

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    I take it this procedure won't work for me as my boot lock is so seized that the key will only go in 2/3rds of the way?
     
  13. OP
    Dec

    Dec Senior Member

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    Do you mean the suggestion below Jools?
    What car and what year is the car?

    Dec

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  14. jools182

    jools182 Senior Member

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    W202 C250 D 1995 saloon
     
  15. OP
    Dec

    Dec Senior Member

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    Same lock as pictured then. It all depends how seized up the lock is, flooding the lock with the boot in the open position is the simplest thing to try first, that doesn’t necessarily mean that you will succeed, if you fail then the only option is to dismantle the lock. Dismantling and greasing the lock will cure the fault but do try the “quick fix” first.
    Don’t try to force the key in, penetrating oil/WD40 is best.

    It shouldn’t really be called Quick Fix because it could take for ever, you might only have a 20% chance of success.

    Dec
     
  16. Top Cat

    Top Cat Senior Member

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    I'm having a similar problem here with my 202 estate boot lock, which does indeed look a little different to the above lock as it doesn't have a push/spring return action to it. Over the weekend I've been gradually flooding it out with penetrating oil, now I can get the key all the way in whereas before it would only go in about half an inch - I did have to use a slightly hooked dental cleaning device to work the wafers inside to get this far.

    I'm now at the point where the key goes in fully but still nothing turns, I shall continue flushing with penetrating oil and may eventually need to remove the lock, so does anyone have a photo (or link) of what is different about the estate tailgate lock versus a regular boot lid lock?
     
    Last edited: Nov 22, 2010
  17. OP
    Dec

    Dec Senior Member

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    The Haynes manual covers the tailgate lock, when the inner trim is removed the lock mechanism seems quite exposed, its hard to tell from the poor quality pictures but it looks to me that that lock could be freed up from the inside and without dismantling it…I think!

    The fact your key now enters the lock fully means that the barrel should now turn. There is a lever at the end of the lock barrel, I think it is this lever that’s stuck and that’s what’s stopping the barrel from turning.

    Closest thing to a picture… http://forums.mercedesclub.org.uk/showthread.php?t=73914


    Dec
     
  18. Top Cat

    Top Cat Senior Member

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    Today I got mine all stripped out and sorted, this was on a 202 estate tailgate. I shall get a write-up with plenty of photos on here tomorrow as my fingers need to thaw out a bit right now, but basically it wasn't the lock wafers, just the cylinder had seized in it's own housing, but using a big pair of molegrips and lots of penetrating fluid seemed to free it up.
     
  19. Top Cat

    Top Cat Senior Member

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    The 202 tailgate lock is different externally to the saloon, and of course it is mounted and operates differently as well. To get to it, first remove the inner boot carpet/trim by popping out the fasteners, with the tailgate open you will then see this:

    [​IMG]

    Pull the rod circled in red to the left, this will disconnect the handle from the mechanism so you MUST NOW put a piece of carpet or similar over the catch that sits horizontally just above the bumper to prevent it from shutting completely.

    From the outside, undo every screw you can see on the underside of the trim that sits above the number plate. Remove the number plate lights. Now on the inside, preferably using an 8mm ratchet ring spanner as access is tight and awkward, you need to undo the nuts holding the aforementioned trim circled below (1 at each end). DO BE CAREFUL, THIS AREA IS FULL OF SHARP EDGES WHICH YOU HAVE TO REACH PAST AND INSIDE.

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    The nuts are captive so don’t worry, after what seems like quite a few turns the trim will lift away from the tailgate. Disconnect the wiring to the number plate lights and remove the trim. There are now 2 screws newly exposed which actually hold the lock in place (in the green box below). Undo these and the complete lock/handle assembly will rest inside the tailgate cavity.

    [​IMG]

    Back inside, disconnect the yellow vacuum line and pull it clear to the left, also pull the number plate left hand light wires out of the way.

    [​IMG]

    The complete lock & handle assembly will now wiggle out of the large space in the metal work on the left of centre.

    [​IMG]

    more......
     
  20. Top Cat

    Top Cat Senior Member

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    Move indoors now, here is the assembly placed in a tray so that you don’t lose any small pieces. This is the rear view and is where all the action takes place

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    Lever off the brass circlip from the shaft, shown below are the external moving components that make up part of the lock/unlock cycle. Note how the spring is fitted (circled in red)

    [​IMG]

    This is actually how the spring gets re-assembled onto the following piece (also circled in red). The green circle is a peg/hole arrangement that allows or prevents the handle from operating, depending upon whether the lock is engaged or not. Before re-assembly make sure this peg/hole arrangement IS ENGAGED and the lock is UNLOCKED or you may not be able to open the tailgate.

    [​IMG]

    Here is the rear of the lock in detail

    [​IMG]

    Simply pull off the spring on the shaft and clean all the hardened grease from this shaft and all that has been removed and the rotating parts around it. My lock was seized, so I sprayed a good amount of penetrating fluid into it from the front and rear, I wiggled it every few minutes, and gradually I freed up the brass ‘castellated’ piece around the shaft which then rotated and moved freely. This allowed me to get more fluid under it and deeper to the innards. A few minutes later, using molegrips on the shaft and giving it a firmer twist, the whole lot became free. Several more applications of penetrating fluid, lots of wiggling of the shaft and the key in the lock and the grating/scratching noise stopped and a nice fluid movement had returned. I lightly greased up every moving part, forcing it into any crevice that I could using a modelling paintbrush, then reassembled in reverse order. Before finally refitting into the tailgate, I sprayed a good squirt of silicone spray into the front of the lock where the key goes, I would now imagine that turning a key every now and again in this lock will keep it working.

    If, after attempting the last step you still have no luck, I would imagine that you need to try to pull out the assembly by the shaft, as seizure is probably caused by more severe corrosion. This is likely to be very tight and could take some time, luckily for me I did not need to go any further so I cannot comment on what you need to do and what you might find hereoin in. You may benefit from referring to the earlier images in this thread as posted by Dec, this ought to be something like what you will encounter as you delve further into the mechanics of the lock barrel and its rear rotating section which looks to be pressed into the external housing.
     

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