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W124 300d auto gearbox advice please

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by richyba, Nov 30, 2012.

  1. richyba

    richyba Active Senior Members

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    Hi all, I have recently bought a lovely 1982 SLC C107 which has had an OM603 engine and auto from a 92 W124 300d fitted. The conversion has been really well done but I get the feeling the guy lost heart towards the end (dont blame him!) and I have a few things to sort, one of my concerns is that the box has a very erratic and rough change. The throttle set up is very crude and i will improve that but my main question is how does the w124 diesel box get its control signals and how are the change speeds set?

    I have to change the diff ratio yet but I would like to get a handle on what might be involved in getting the box right.
     
  2. spock500

    spock500 Senior Member

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    If it's anything like my old C250D which had a 722.4 box, it will shift using a vacuum from the engine.

    Check all pipes, especially the small white nylon as these tend to be for vacuum related tasks.

    Do you know the model of box fitted?
     
  3. OP
    richyba

    richyba Active Senior Members

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    Thanks for that, as far as I know it is a 722.4 but I cannot see any vacuum connections which could well be the problem! Anyone any idea which side of the box they go to?
     
  4. spock500

    spock500 Senior Member

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    There's a white nylon pipe which (from memory) runs down the left side of the box. If you go onto the EPC site you should be able to get a diagram for the vacuum layout.

    edit: I just had a look at some pics which show the pipe exiting a T piece after the vacuum pump then running the length of the block to the right. I am assuming it then either crosses over the top of the bell housing or continues on down the right side.
     
    Last edited: Nov 30, 2012
  5. kth286

    kth286 Senior Member

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    on the diesel it will be from a vacuum pump.

    as I'm not into diesels i don't know where it is located on that engine.
     
  6. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

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    On the timing cover directly in front of the injection pump
     
  7. OP
    richyba

    richyba Active Senior Members

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    Thanks for the help, there is a vacuum pipe heading down to the box, I will have to get it on a ramp to see the story, I assume the change settings are set by the throttle cable which to be honest is a shambles and needs sorting, would that be likely to make for a harsh gearchange? Also is it possible to set the change speeds (or revs) or are they pre set?:confused:
     
  8. brianbrian

    brianbrian Senior Member

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    You can adjust the kick down cable at end of throttle, O/side of engine you will see a cable coming up from the g/box, do check the vaccum pipe to g/box as this can give harsh changes. Hope this helps
     
  9. teabag

    teabag Senior Member

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    The pipe in question goes to the vacuum modulation box (Assembly no 72 on the drawing in the link below), you can control the feel (harshness/softness) of the changes by turning the valve either clockwise or anti-clockwise on it's slots to get the desired effect but I can't remember which way is which so you will have to trial and error.

    http://mb.ilcats.ru/part/class/1/cc...bgr/045/retcat/15S/rettype/124/retsubtype/133
     
  10. star

    star Forum Supporter Authorised Forum Supporter

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    I dont think the vac pipe runs directly from the pump to gearbox as it would be at max vac, it should run thru a valve on the throtle linkage that alters the vac according to throtle position. The vac valve on side of gearbox is to set the modulating pressures. It should also have a control cable that determines change point.
     
  11. teabag

    teabag Senior Member

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    I think you are right, this link shows the routing of the vac pipes.

    http://mb.ilcats.ru/part/class/1/cc...imgno/5/retcat/15S/rettype/124/retsubtype/133
     
  12. pikeydave

    pikeydave Senior Member

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  13. brianbrian

    brianbrian Senior Member

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    The vaccuum pipe to the g/box runs from the deisel fuel injection pump. Hope this helps
     
  14. Doug1234

    Doug1234 Senior Member

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  15. OP
    richyba

    richyba Active Senior Members

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    Thanks for some real help ful answers there, gives me some work to do, first thing to do is cure a couple of oil leaks in hoses etc. The ATF is ruining my hair:lol:
     
  16. Doug1234

    Doug1234 Senior Member

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    Go on Ebay and look for a shop called Wunderpartz, the gearbox oil cooler hoses are a very nice price ,ie very cheap.
    The parts they sell are excellent quality and once you start adding up the cost of things they make the usual sources look very exspensive
     
  17. brianbrian

    brianbrian Senior Member

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    Did the person who done or started the conversion wire the glow plugs to the ignition? this is a must for easy starting. Also convert engine start and stop engine vaccumm controled. Hope this helps
     
  18. OP
    richyba

    richyba Active Senior Members

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    Yeah he has actually done a sound job of that, it has the ignition from the W124 and the vac stop works A1 so he could plumb some vacuum OK! :lol:
     

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