R129 1994 wiper mystery

Discussion in 'Engine' started by Watchcame430, Apr 11, 2014.

  1. Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Hi all,
    Having a major issue with the wiper on my 129.
    It was barely working as the grease had gone hard inside.

    I took everything part .... Cleaned it all up and regreased before putting it back together.

    I had taken care to put it back together the same way ... Or so I thought.
    As can be seen from the pictures below the wiper is not set right.

    I have spent hours today trying different adjustments but clearly not doing something right.

    Does anyone have any experience with them?

    Just to add this is a 94 so it is the early version which does not have the pull of cover. It is a nightmare to open.

    [​IMG]

    The above shows the blade at its shortest which should be in the middle?

    I am at a lost as everything I do changes nothing.

    Thanks
     
  2. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Another ... As you can see it hits the a pillar on the driver side

    [​IMG]
     
  3. Dec

    Dec Hardcore MB Enthusiast

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    Is the rear of the mechanism the same layout as the picture below?
    are there any alignment marks on your mechanism similar to the alignment marks in the one in picture below?

    Dec

    [​IMG]
     
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  4. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Great find ... Mine is different but I hope they did the same on the R129. Too dark now but wil pull it out tomorrow and have a look... Cheers!
     
  5. Dec

    Dec Hardcore MB Enthusiast

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    The fact that the tip of the blades hits the side trim means that the mechanism is broken and the only solution is to jam the mechanism with a lolly pop stick as illustrated below or replace the whole mechanism or use a wiper blade that is 4 inches shorter than the one that you have fitted at the moment.

    Dec

    [​IMG]
     
  6. Dec

    Dec Hardcore MB Enthusiast

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    Take pictures tomorrow, of the rear of the mechanism when you are at it.

    Dec
     
  7. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    This above version is the later type and pretty sure mine isn't broken but does need further exploration incase you are right.
    Mine looks like below ...
    [​IMG]
     
  8. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    This is the rear...

    [​IMG]
     
  9. Dec

    Dec Hardcore MB Enthusiast

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    I think maybe you didn’t park the motor before you reattached it to the mechanism.
    See post 15 here… http://www.mbclub.co.uk/forums/bodywork/47456-c-class-180-93-wipers-park-mid-screen.html

    It’s a different mechanism but the principle is the same, there should also be similar alignment marks on that mechanism of yours too, not exactly the same though.

    If the tip of the blade is hitting the side windscreen trim then there is definitely a broken “coged wheel” or broken teeth inside the mechanising as illustrated in picture in post #5 above.

    Dec
     
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  10. Sp!ke

    Sp!ke Administrator Staff Member

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    Is the blade itself on the right way up?

    If I recall correctly the blade is longer one way up.
     
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  11. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Thanks for this ... The motor parking thing does sound interesting. Will see if any reference to it being the same for the R129 but will try it anyway even if I don't. It does make sense.
    I know what you are saying about the cogs but I totally disassembled the whole entire unit, cleaned, greased and rebuilt the whole thing so know they are ok. The cogs were like new.
    Thanks for your help, plan to get stuck in again the morning and will report back!
     
  12. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Thanks sp!ke will double check. I just reattached it so should be ok as was working ok prior to it getting stiff.
    Ironically the movement is gorgeous now until it catches!
     
  13. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Found one pic I took of the gear ...
    Only one metal brace in place at this stage when rebuilding.

    [​IMG]
     
  14. Dec

    Dec Hardcore MB Enthusiast

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    I think it is longer one way up alright but it only goes on one way, in any case, if the blade was too long then it would be hitting both sides of the windscreen.
    The blade is not being retracted as it approaches the driver side windscreen trim and so it hits it... I bet you can push the blade/arm inwards by hand… it should not be possible to do that.

    The gear in post #5 (1 bottom right small picture) is the one that’s slipping then, the blade I think is 24 inches long.

    Before you remove the mechanism from the car in the morning, stop the blade at the point where it is hitting the side trim (turn off ignition when the blade is on the driver side) then try pushing the arm/blade inwards… if you can push the arm/blade inwards then the mechanism is broken and you need a lollypop stick fix.

    The wiper blade moves inwards and outwards as it sweeps the screen, it should not be possible to move the arm/blade inwards or outwards… by hand… at any point on the windscreen.

    Dec
     
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  15. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    It is being retracted as it moves across the windcscreen but because it is off centre it starts moving out again before it has completed its sweep if that makes sense. When the wiper is straight up I believe the blade should be in (i.e at its shortest) but its not ... It is about 15 degrees past (the first photo)
    Will try all you suggest though ... Wish the sun would hurry up! Its annoying me now and I have other exciting things to do on the car!

    Also to add .. Pretty sure I tried pulling it and I couldn't get it do pull out (need the lolly stick)
     
  16. rorf

    rorf Hardcore MB Enthusiast

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    Make sure you use the correct 129 arm and wiper blade, you cannot use the 124 parts. Did you disassemble the whole unit?
     
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  17. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    I am using the correct arm and blade. It was working ok before I took it apart just painfully slow. (Almost stopping as it swept the screen)
    All the same parts going back in.

    Also to add I did take everything apart except for the arm on rear as this is was in good condition. Not sure it comes apart without drilling anyway if that makes sense :)
     
    Last edited: Apr 12, 2014
  18. Dec

    Dec Hardcore MB Enthusiast

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    I know you can’t take the cover off yours to see the mechanism in action but the video below shows what’s happening inside yours. It’s the cogged wheel that’s pulling the arm in and out and that cogged wheel is slipping on its shaft when the blade is over at the driver side. Good illustration in video below.

    [YOUTUBE]94rCjXDV3BE[/YOUTUBE]

    The blade should be shortest at the sides and the top of the screen and longest at both corners, picture below illustrates this very well.

    Picture source… Technical Curiosities: Mercedes? Monoblade Wiper ? Spannerhead
    [​IMG]
    [​IMG]

    Take note of the wiper mechanism part number for future reference if you decide to get a replacement the unit from eBay.

    Dec
     
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  19. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Thanks for the above and that might be the issue.
    One problem though to prove for sure is that it's got worse since I fiddled this morning.
    I reset the motor as suggested and now park is the middle of the screen.
    I am assuming someone fitted the new motor that is in there and it was set wrong in the first place. Now I have reset it everything else is out of whack.
    No markings on the rear at all sadly either to guide.
    I am going to move the arm again ... One question though ... Park should be on drivers side?
     
  20. OP
    OP
    Watchcame430

    Watchcame430 Hardcore MB Enthusiast

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    Further probing ... I disconnected the motor and moved the blade across by hand.
    I found it doesn't pull in early enough at the top or at the pillars.
    Can therefore rule out the motor influencing things and possibly point to the spinning cog you mention but I can't help but feel there must be something needs adjusting.
    I can get a new mech but I want to fix it today ideally ...
     

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