W124 - 300TE Autobox .......erratic mode?

Discussion in 'Engine' started by punjabi, Dec 16, 2008.

  1. punjabi

    punjabi Hardcore MB Enthusiast

    Messages:
    110
    Joined:
    Apr 22, 2005
    Location:
    Surrey, UK
    Car:
    V230, 300TE
    The auto box has been fine until a recent 500 mile motorway day-trip after which it has become somewhat erratic when sometimes it shifts from 1st to 2nd with a delayed and a slight high rev motion :confused:.
    This only happens when it has been driven a while and at random - not all the time! The tranny oil is clean and at the correct level, although I was thinking of changing the oil & filter to see if it cures the problem but the weather has been rather wet and cold!
    The car has done 190K and is otherwise in excellent mech/elec condition. Any ideas what could be causing the problematic behaviour of the tranny?
     
  2. SilverSaloon

    SilverSaloon MB Club Veteran

    Messages:
    7,759
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    sounds like a vacuum leak. Check all the vacuum pipes for leaks.
     
  3. Dieselman

    Dieselman Banned

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    Car:
    Peugeot 403 Convertible
    A vacuum leak will give a hard shift, this sounds like low fluid, sticking valve or slipping clutch.

    If the ATF hasn't been changed for a while it's worth a go.

    The Vac modulator might not be adjusted correctly, try disconnecting the vac line and see what happens. It should bang into the next gear firmly.
     
  4. OP
    OP
    punjabi

    punjabi Hardcore MB Enthusiast

    Messages:
    110
    Joined:
    Apr 22, 2005
    Location:
    Surrey, UK
    Car:
    V230, 300TE
    DM,
    Fluid level appears OK - where/what is the Vac Modulator? Which is the 'vac line' - the 10mm clear pipe leading from the servo to under the air cleaner housing or inlet manifold?
    Any difference in ATF & Dextron II/III?
     
  5. Dieselman

    Dieselman Banned

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    The modulator is on the side of the gearbox and has a line running from the inlet manifold down to the modulator. Unplug the line and plug it so air doesn't leak into the manifold.
     
  6. SilverSaloon

    SilverSaloon MB Club Veteran

    Messages:
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    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    I adusted my modulator and now have good changes, where it was flaring before. However the OP states that it suddenly started to happen indicating something may of come adrift/adjusted.....
     
  7. Dieselman

    Dieselman Banned

    Messages:
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    Joined:
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    Car:
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    But it won't be a vac leak. If the vac leaks a hard shift ensues, not a slurred one.
    Pulling off the vac line is a test of the rest of the box.
     

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