M46 OD sticks on

Discussion in 'General Motoring' started by James Sweet, Jan 24, 2004.

  1. James Sweet

    James Sweet Guest

    My friend's 740 GLE has an odd problem with the overdrive, you engage it and
    it clicks in immediatly, but when you press the button to disengage it the
    dash indicator goes out but the OD stays in gear, you can even downshift
    with it still in OD, eventually at a random time it disengages with a
    somewhat unhealthy sound. It never seems to slip though, is this something
    that can be fixed or should we grab a new tranny from a junkyard?
    James Sweet, Jan 24, 2004
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  2. James Sweet

    don hodgdon Guest

    Sounds like the relay might be crapping out. Is there an audible click when
    trying to disengage the OD?

    Resolder or replace.
    don hodgdon, Jan 24, 2004
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  3. James Sweet

    James Sweet Guest

    The relay works fine, it clicks and the dash indicator works fine, definitly
    something in the OD itself, as I said it makes an unhealthy grinding sound
    sometimes when it finally does disengage, obviously not an electrical
    James Sweet, Jan 24, 2004
  4. James Sweet

    Martijn Guest

    Perhaps the solenoid wich is mounted on the outside of the OD does not work
    propperly. You can also hear it click if you engage the OD. Also
    check/replace/fill the od's oil and clean the metal filter.

    Martijn, Jan 24, 2004
  5. James Sweet

    Duane Hoberg Guest

    Four potential problems. Listed in ease of diagnoses. Most likey number

    The relay is allowing power through even after you "turn it off". Remove
    the cover to access the fuses and relays. TWO people in auto. Drive the
    auto, engage the OD, when the OD is truned off, and the OD stays engaged,
    non driver reaches in and taps the relay sharply with handle of screwdriver
    or something similar. If OD drops out when relay hit, coil contacts or
    internal circuitry is the problem with the relay. Remove the relay, pop the
    cover and look at the coil contacts. claen or replace the relay if

    Second is Solenoid on OD itself. It has two internal O-rings that after a
    hundred thousand miles or so, allow fluid past into the coil area. This
    fluid keeps an internal piston from moving and keeps the OD on until the
    fluid drains off. A temporary fix is to remove the internals of the
    solenoid and clena it out, which will last a few thousand miles if you are
    lucky. Replacing the O-rings is like getting a new solenoid without the
    Dealer cost. O-rings run $5.10 from me and come with instructions.

    Third problem is much more difficult to repair since it indicates and
    internal problem with the OD. There is a small hole between the solenoid
    and the bottom of the dashpot where ALL the fluid to engage or disengage the
    OD must pass. IF, this hole gets blocked by a part of an O-ring, the OD
    will not disengage. To access and clean, the solenoid is removed, the pan
    on the bottom of the OD comes off and the far left plug and internal parts
    are removed. Th eprot is the blown clean from the solenoid side to the
    internal. Takes a right angle blow gun or can of air with a squirt tube and
    some contortions on your part. Replace the offending O-ring and put
    everything back in the correct order and your good to go.

    Some 700's have a situation where one or both of the relief valve springs
    break and the valve gets hung up not allowing a release. There is usually
    some slippage that occurs with this situation. Repair is accessed like
    number three above since the springs are under that same plug.

    For some detailed instructions for the soelnoid, contact me at ODGuru at kc
    dot rr dot com.

    ODGuru Laycock Only
    Duane Hoberg, Jan 24, 2004
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