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Can't lower the piston

Discussion in 'Fisher Engineering Discussion' started by 94K2500, Jan 6, 2007.

  1. 94K2500

    94K2500 Junior Member
    Messages: 3


    I've got a Fisher 7' on my 94 Silverado 3/4 ton that I bought new. It's always worked fine. Went to put it on my truck and found that who ever drove it last had raised the lift piston all the way. I'm 5'9" and 165lbs and no matter how much I pulled on it it wasn't budging.

    I tried unloading the pressure from the system by moving the control up down and right and left as detailed in the manual and I cannot move the lever left and right as well.

    Fluid is full. belt is tight. Haven't been using the truck recently due to the price of gas and it's 70 degrees outside in south west Connecticut on January 5th. But it's probably high time to get it right so when it does get cold and snow I'm not figuring it out on the fly.

    Any help/advise is appreciated.

  2. BigDave12768

    BigDave12768 PlowSite.com Addict
    Messages: 1,446

    DIlectric grease, Diletric grease, DIlectric grease. Make sure all your connection are good and grounds. And Diletric grease is a big help. I would start their. Check the big plug first. Also once you get it moving make sure you grease the pistons
  3. Plowfast9957

    Plowfast9957 Senior Member
    Messages: 280

    He said it has a belt so dielectric grease wont help him because there is no plug to put it on. I would use a floor jack to mount the plow then jack the plow up as far as you can then hook the chain to the a frame and let the jack down with the control lever in float. That should gave you enough weight to pull it down.
  4. Rickco

    Rickco Member
    Messages: 89

    Just use a big bar. There is no substitute for leverage. Make sure it's in the float position.
  5. chaseatg

    chaseatg Member
    Messages: 94


    Sean: I take it that this is a belt drive hyd system? If so make sure your quick connects are plugged in all the way. Tap the ball on the quick connects to make sure they are not stuck before connecting.
    Sounds as if your spool valve might be stuck, inspect the cables at the valve, I have found that with the lack of use the spools get stuck, try spraying some penetrating oil on the valve spools, you can also tap the spool end gently with a small hammer to free the valves. When the valve is working freely then hook up the hoses with the engine off and place the control in the float position. Spray your lift cylinder with penetrating oil also, the packing becomes dry from sitting, raise and lower the plow, repeat till the lift cylinder is back to it's old self. Then sit back and pray for snow like the rest of us.
  6. 94K2500

    94K2500 Junior Member
    Messages: 3

    Trying the jack.

    Hi All

    Thanks for the tips

    I've got some spare chain wrap around the lift chain to 'lengthen' it as wll. I will post the results.

    Any ideas on why I get no left and right movement out of the control. This is with and without the hydraulics connected to the plow.

    I'm sure that the under the hood components need some service but I'm at a loss as to what to do with it and cannot find anything on the web to detail service instructions.

    The documentation I received with it is sketchy and doesn't go into it. I'm trying to avoid going to a service center although with the weather we've been having I'm sure this is an ideal time.

    Once again thanks for the assistance.

  7. chaseatg

    chaseatg Member
    Messages: 94

    Your welcome Sean, glad to be of help.
    Your angle cylinder packings could be dried out as well, spray them with penetrating oil also.
    Take off the quick connects for the angle cylinders and try moving them manually.
    Pray for snow.
  8. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    My 85 did this because the left knee would always hit the joystick whenever I got in or out of the truck. I found it was pretty easy to drop the piston back down, but the truck has to be running the stick has to be in the down or float position.

    What do you mean no left or right though? If I've read your description correctly you have an underhood belt driven pump and your plow is not currentlyon the truck. Are you saying you can't move the joystick itself left and right?
  9. 94K2500

    94K2500 Junior Member
    Messages: 3

    Got it going again ---Now lets have some snow!!!

    Hi All;

    First off thanks to all of you who read and responded to my post. I took a bit of advice from all of you and now it's working OK again.

    Last night I gave the cylinders a spray with penetrating oil as well as the mechanism under the hood that actuates the plow. I also gave a gentle rap to all the above mentioned with a small hammer and verified that the balls in the disconnect fittings were not stuck

    After work today I used a hydraulic jack to raise the frame of the plow up. With the piston all the way at the top it still wasn't enough. I then took a length of chain and hooked it to the triangle and wrapped it around the lift chain on the plow.

    The weight of the plow was enough to convince the lift cylinder to compress, once down I hooked it up to the lift chain normally...started the truck and it worked like a champ.

    Still wouldn't angle though. I sprayed the under the hood cable assembly and the actuators with some more penetrating oil and did the same to the end of the cable inside the truck. I got it to move left but no right. After more lubrication and some gentle persuasion with the ball peen it grudgingly moved right.

    Yet more lubrication and cycling it from side to side it now works as well as I remember it always working.

    Thanks again for all of the help. Now if we could only get some snow here in the Danbury CT area, it would make the effort worthwhile.