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bad cylinder?

Discussion in 'Fisher Engineering Discussion' started by Megunticook, Feb 5, 2007.

  1. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    I have an older belt-driven Fisher plow on my truck. I had a small amount of fluid leaking out of what I thought was the brass "ell" fitting where the hose attaches to one of the angle cylinders. I tightened it up a few days ago but found it was a little tricky because if I rotated the "ell" clockwise the hole where the hose screws in ended up facing the truck, which routed the hose directly into part of the a-frame. I tried unscrewing the "ell" and restarting it in a different position, so as it tightened up the hole would would be facing up/forward, but no matter what position I started it in it would always thread the same way and end up in the same position. So I finally just used a little more muscle than I normally would to keep turning it until there was room for the hose (I had some anti-seize on the threads and had to really lean on the wrench to get it to rotate that far).

    Now I'm finding that when I try to angle the blade in one direction (the direction where that particular cylinder is extending to push that side of the blade away from the truck), I'm getting that high-pitched "squealing" sound (the sound you get if you don't let up on the control after you "max out" a cylinder by extending it all the way) and the blade is very slow to move. Eventually the cylinder will extend, but it takes a little time and the pump is squealing the whole time.

    Now I suspect there is something wrong in that cylinder. What would be causing that sound and sluggishness? A bad seal? I'm thinking maybe the leak was not from the brass "ell" but from the cylinder itself (it's really hard to tell from looking at it--the whole bottom of the cylinder is wet but I can't tell exactly where the source of the leak is). There is still some fluid leaking.

    I keep my pump reservoir topped off every time I plow, don't seem to be losing a great deal of fluid, although when I was fiddling with the el some fluid spilled out of the cylinder and disconnected hose. But I topped off after reconnecting the hose and hoisting, angling the blade (and I always make sure the lift cylinder is fully retracted before refilling the reservior). This should refill the cylinder and purge any air, right?

    Any ideas? Thanks.
  2. LON

    LON Senior Member
    Messages: 749

    That sound you here is the valve blowing over relief. Disconnect the cylinders from the back of the moldboard and see if the moldboard will pivot freely side to side. If this moves freely then do a hydraulic test of the cylinder you think is bad, basically while it is disconnected angle it to the side that makes than cylinder extend. If it is slow & blowing over the relief then suspect either the line or cylinder. What you did by tightening the ell has nothing to do with the problem.
  3. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Thanks for the clarifications.

    I bought this plow rig used, and it wan't new when I got it. I've been replacing and overhauling bit by bit, got new hoses and quick-connects from my local Fisher dealer, plus installed a new inline filter for the fluid.

    My local Fisher dealer's first guess was the quick-connect fitting when I briefly described it over the phone (though he relented as soon as I reminded him that I'd just bought new quick-connects and hose from him recently.

    But it's definitely the case that this issue didn't crop up until after it has gotten quite cold here--and I had a hell of a time getting a different disconnect on this rig apart the other week (yes, I did relieve the pressure in the system by opening the valves before trying). I wonder if there might be an issue there?

    Doubt it, though. I'm guessing with the leak that this cylinder is shot inside.

    I did loosen the head nut on that cylinder an eighth of a turn or so (dealer's suggestion), it turned real easy (surprised me), haven't checked to see if it will leak. I don't think that was the problem, I worked the thing back and forth pretty good by hand back before Christmas and it moved just fine.
  4. wirenut

    wirenut Senior Member
    from nh
    Messages: 529

    raise the plow, take the quic disco's off get a bucket and move plow l/r
    and mt each cyl. make sure things are not froze up.
    although its much easier to pull both pistons and go inside
    and take em apart