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Brake fluid or oil in sealed wet disc brakes?

Discussion in 'Compact Wheel Loaders' started by Steve Bowman, Oct 21, 2018.

  1. Steve Bowman

    Steve Bowman Well-Known Member

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    Next item on my rebuild list is the brakes. If it matters, it is a Waldon loader. They are hydraulically applied wet discs.

    It has a conventional type master cylinder that supplies oil to the brakes. They have been working when I press the pedal, but I took the cap off to check the fluid and was not pleased at what I found.

    The "fluid" that was in there was severely contaminated. Very thin, but with like chunks of grey slime in it.

    I disassembled the master cylinder and found very little corrosion. Which surprised me given the condition of the fluid. For now, I just reassembled with the seals that where there, as they looked adequate. I will work my way down the system cleaning out the old, nasty fluid, but what do do for new brake fluid?

    My experience has been that hydraulic oil would be the likely fluid to use for sealed brakes, but with the viscosity of what came out of it, it was likely mostly brake fluid. But, past maintenance of this loader was very much hit and miss, so it could have been wrong.

    Brake fluid is sort of a one way street I guess. Once the seals swell, can't go back. With oil, it should function even if wrong? Like I mentioned, the brakes have been working fairly well in the short about of operation I have done to this point.



    Anyway, any advice?

    Thanks
     
  2. 92U 3406

    92U 3406 Senior Member

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    Typically anything petroleum based put into a system designed for DOT 3 or 4 brake fluid will swell the rubber. I've see ATF or brake fluid used in hydraulic wet brake systems (NOT interchangeably, one or the other. Whatever the mfg specifies). I would definitely research and find out what is supposed to be in there because the wrong fluid has a good chance to ruin all the rubber parts.
     
  3. Steve Bowman

    Steve Bowman Well-Known Member

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    Thanks for that.

    I have more info now. The line from the master cylinder tees and one line goes back to the powertrain pump. I blew the lines out, and the fluid had a brown/redish tint. I am guessing transmission fluid now.

    I suspect the line is a neautralizer for the pump? The disconnected line here. Solenoids are F and R. 20181021_121307.jpg

    So, would that be a closed circuit in the pump? I would think so, given the color of the oil. Notice the bleeder also.
     
  4. funwithfuel

    funwithfuel Senior Member

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    That's for a separate circuit. That is for "inching" hydrostatic drive needs to be disengaged so to speak. Your linkage should have a valve under the floor which applies pressure to the port you pointed out.
    Hydraulic oil is separate from brake apply oil which should also be separate from wet brake oil. As 92U3406 said, its gonna be very critical that you find out what was original to the machine. Ops and service manual are going to be needed.

    BTW, what are you working on?
     
  5. Steve Bowman

    Steve Bowman Well-Known Member

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    I had forgotten, months ago, when I was trying to identify the serial # of this machine, I had contacted Waldon directly. They sent me a couple of PDF files. I went back and found that they contained the recommended fluids. It says Hyd oil, :)

    As far as the circuit, it is just the master cylinder that feeds a tee at the left front. The other side of the tee goes to the right front, which also has a tee. That tee goes back to the powertrain pump.

    Now, with the correct oil, I hope there is minimal lasting damage from incorrect fluid used in the past.

    upload_2018-10-21_17-27-10.png
     
  6. funwithfuel

    funwithfuel Senior Member

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    So, I would guess the slimy stuff was someone added brake fluid to it not knowing. At least you caught it. Good deal
     
  7. Steve Bowman

    Steve Bowman Well-Known Member

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    Hope so. I think short of disassembly, there is little chance of getting all of the oil in the system replaced.



    Oh, to answer your question it's a Waldon 7000
     
  8. RZucker

    RZucker Senior Member

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    I ran into the same mess on a three wheel Terragator fertilizer spreader with a John Deere Skidder axle, the mutts had been adding brake fluid to the power convertor(master cylinder) and it was full of slime, but still was working. The big problem was that the mutts had been pumping gear lube into a diff with wet brakes that ran on hydraulic fluid, That was the no-stop issue. We flushed the pressure system through the bleeder valves and flushed the rear end housing with diesel fuel 3 times and eventually the brakes came back. The Chief Mutt told me I was crazy to run Hydraulic oil in a differential... I told him he was a stupid ass for not knowing the difference. It probably has 90 wt in it now.
     
  9. Steve Bowman

    Steve Bowman Well-Known Member

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    Old habits are hard to break sometimes.