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Thread: raise and lower cab

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    4 Star General Steel Soldiers Vendor m-35tom's Avatar
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    Default raise and lower cab

    94 A0 VERY hard to raise cab, VERY hard to lower cab. Air pump works very hard and labored, manual pump very hard to operate handle. Has steadily gotten worse over past 10 times of opening. Ideas? will not go over center when open. Will not self close after being over center.
    tom bauer m-621
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    4 Star General NDT's Avatar
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    Sounds like a plugged restrictor orifice.

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    How does the fluid look? Any water in the system. That will cause those issues.

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    4 Star General Steel Soldiers Vendor m-35tom's Avatar
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    How many restrictor orifice are there and where are they? Should the cab close on its weight or does it have to be pumped all the way down?
    Is there a locking valve in the cylinder?
    tom bauer m-621
    air conditioned - 28 air
    6 wheel drive - 3 air lockers
    power steering - hydraulic - over 250 kits sold
    fast - now 1 of 43 with .69 od !!!
    m-35 transmission expert
    avatar - 64mph @ 2400 rpm with 14.5R20XL

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    The cab will usually slowly creep down on its own once you get it started going down.

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    4 Star General Steel Soldiers Vendor m-35tom's Avatar
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    So cab needs to be pumped all the way down is normal? I thought I read it would close with a flow control but that may have been another series of trucks. New fluid, clean, no air, no water.
    I tried the suspension circuit and it worked fine as did the spare. Then I tried the cab, no go so I tried the spare again no go on that either just pumps against high pressure. Same not with suspension. Tried several other settings and the suspension worked for 2" and all others still locked. So I should remove and clean each control valve?
    tom bauer m-621
    air conditioned - 28 air
    6 wheel drive - 3 air lockers
    power steering - hydraulic - over 250 kits sold
    fast - now 1 of 43 with .69 od !!!
    m-35 transmission expert
    avatar - 64mph @ 2400 rpm with 14.5R20XL

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    You may have to bleed the spare hyd feed. Happens. When you run your pump is it puffing out the breather on the pump?

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    4 Star General snowtrac nome's Avatar
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    I had the same problem once it was cold as he double toothpick and dark a few days later I found one of the other control knobs turned a bit. As a note to self check all knobs are straight up and down except for the function you are using.

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    4 Star General Steel Soldiers Vendor m-35tom's Avatar
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    I set bottom to cab lift and top to raise. Pump hand pump. Pumps up high pressure and will not pump more. Then turn top knob to lower, you can hear the ping as the pressure is released. Play with all combinations of settings and occasionally it will work fine for 5 or 6 pumps until jams again. Sometimes cab will start to raise easily for a few inches then stop, pump will not go any more, nor will it lower. Will lower 1/8" at a time by turning top knob from raise to lower repeatedly.
    Last edited by m-35tom; 01-25-2019 at 14:48.
    tom bauer m-621
    air conditioned - 28 air
    6 wheel drive - 3 air lockers
    power steering - hydraulic - over 250 kits sold
    fast - now 1 of 43 with .69 od !!!
    m-35 transmission expert
    avatar - 64mph @ 2400 rpm with 14.5R20XL

  10. #10
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    There are 2 filters in the control box on top there are hex head covers that come off and then the filters unscrew and come out. The parts tm shows the breakdown of the control box. There are 2 different styles. Again any water in the system will cause issues like you are having.

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