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  1. #1
    Bronze Member
    Join Date
    Jan 2013
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    71
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    PA
    Tractor
    Massey Ferguson 135 Deluxe (IPTO)

    Default MF 135 Pump Control Valve Leak

    Does anyone know the cause of this leak? The picture was taken when the lift was leaking down.
    Thanks!
    MF 135 Pump Control Valve Leak-mf-135-pump-control-valve

  2. #2
    Bronze Member
    Join Date
    Jan 2013
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    71
    Location
    PA
    Tractor
    Massey Ferguson 135 Deluxe (IPTO)

    Default Re: MF 135 Pump Control Valve Leak

    This leak is caused by a failure of the pump control valve diaphragm (898254M91). The pump control valve has a weep hole on the bottom of the non-pressurized side of the valve as shown in this photo:
    MF 135 Pump Control Valve Leak-imag0451-jpg).

    When the diaphragm leaks under pressure, hydraulic fluid will exit via the weep hole. Here is a photo of the failed diaphragm:
    MF 135 Pump Control Valve Leak-imag0456-jpg
    Note that the failure was due to the rubber becoming hardened and cracking off of the fabric backing material. In my case the fluid leakage was less when the pressure was greater because the diaphragm moved against spring and the flow was restricted as the fabric gap closed.

    fyi.

  3. #3
    New Member
    Join Date
    Mar 2017
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    1
    Location
    Budapest
    Tractor
    Massey ferguson 135

    Default Re: MF 135 Pump Control Valve Leak

    Quote Originally Posted by klancf51 View Post
    This leak is caused by a failure of the pump control valve diaphragm (898254M91). The pump control valve has a weep hole on the bottom of the non-pressurized side of the valve as shown in this photo:
    MF 135 Pump Control Valve Leak-imag0451-jpg).

    When the diaphragm leaks under pressure, hydraulic fluid will exit via the weep hole. Here is a photo of the failed diaphragm:
    MF 135 Pump Control Valve Leak-imag0456-jpg
    Note that the failure was due to the rubber becoming hardened and cracking off of the fabric backing material. In my case the fluid leakage was less when the pressure was greater because the diaphragm moved against spring and the flow was restricted as the fabric gap closed.

    fyi.
    Hello,

    I have a simillar problem ( the diaphragm broken), so that is why the diaphragm leaks under pressure. Do you think is this a failure of hidraulic dont lift or really weak? I'd like to ask if this problem cause a pressure loss in hydraulic system?

    Thank You in advance!

    gabben85

  4. #4
    Bronze Member
    Join Date
    Jan 2013
    Posts
    71
    Location
    PA
    Tractor
    Massey Ferguson 135 Deluxe (IPTO)

    Default Re: MF 135 Pump Control Valve Leak

    The leak is limited by the remaining diaphragm material and the weep hole. If all of the other parts & seals (pump, O-rings, lift cylinder rings, etc.) in the lift hydraulics are in good condition, this diaphragm leak alone won't cause the lift hydraulics to be non-functional. I suggest starting with hydraulic pressure measurements. There is a port on the lift cover below the transfer plate where you can attach a pressure gauge. Be sure the gauge is correctly rated.

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