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New Holland PowerStar T4.75 Hydraulic Leak

Discussion in 'Agricultural Equipment' started by Steve Frazier, Sep 17, 2020.

  1. Steve Frazier

    Steve Frazier Founder Staff Member

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    Location:
    LaGrangeville, N.Y.
    I have a 2017 PowerStar T4.75 at work and have developed a pretty bad hydraulic leak at the remote valves on the back, it's a stack of 3. I can't really see exactly where the leak is coming from but I have a steady stream coming from behind the bottom valve. I've checked all the bolts that clamp the stack together and the bolts that clamp the port plate to the valve body and all are tight. I can't get any movement of the valve assembly by tugging on it, everything seems tight. I found a blow up diagram online and it appears the only points that could leak are the seams between the valve body stack and the plate that has the quick connect ports attached. Does anyone know of any other possible points?

    My plan of attack is to first remove the port plates one by one and check the seals and then if necessary pull the stack apart and do the same. Any other suggestions?

    The leak is a steady stream that has gotten progressively worse since first discovered, we ran it just long enough to drive it about 4 miles back to the shop. The rate is fast enough now to make an unbroken stream to the ground from the drawbar about 1/16" wide.
     
  2. Steve Frazier

    Steve Frazier Founder Staff Member

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    Location:
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    I replaced the seals on the plates that the quick connects attach to but that wasn't it. I pulled the stack off the tractor and have it on the bench. As best I could tell it appeared the oil was coming from the center level, or the middle valve. I pulled the plates off again and the stack sure seems tight, I honestly don't think the leak is from between the valve bodies.

    Below is the valve stack as it mounts on the back of the tractor. I believe the tractor was originally built with 2 remote valves and I had the dealer add the third to put hydraulics up at the front attachment plate. That's the reason for the rust colored valve. Can someone tell me what the round stud is in the center of each valve (circled in yellow)? Does it penetrate to the oil galley? Could it be the source of the leak?


    NH Valve Body edit.jpg )
     
  3. Steve Frazier

    Steve Frazier Founder Staff Member

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    On closer look, it appears the stack bolt passes through the stud rather than the other way around. Discovered this right at quitting time, I’ll try to extract it Monday. I’m thinking this may be the source of my leak
     
  4. Steve Frazier

    Steve Frazier Founder Staff Member

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    Got it apart, found the problem. I don't know what these little parts do, there's a spring behind them. They are perpendicular to the valve assembly and travel. New seals and "spacer rings" on order. There doesn't seem to be any blemishes in the machining of the bore they insert to, not sure what caused the failure. Tractor has less than 1000 hours on it and very little use of the remote valves.



    New Holland Hydraulic Valve sized.jpg
     
    Tinkerer likes this.
  5. Tinkerer

    Tinkerer Senior Member

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    Strangest looking seal (the white one)I have ever seen.
     
  6. Steve Frazier

    Steve Frazier Founder Staff Member

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    The dealer calls it a spacer ring. It looks like teflon or nylon. Based on its name I guess it takes up the space in the seal groove to keep the seal in place. I keep wondering if you couldn't put a second O ring in there instead.
     
  7. jhonygee

    jhonygee Member

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    Nov 2, 2020
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    Location:
    turkey
    absolutely cannot be put