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Troubleshoot tips for old school Fisher all hydraulic plow

Discussion in 'Fisher Engineering Discussion' started by c_nice_37, Dec 28, 2010.

  1. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    Hi Guys,

    I have a 25yr old Fisher, all hydraulic under the hood style - I believe this is referred to as 'conventional.' I put this on last winter and everything worked pretty well. Near the end of the winter, the plow got really slow so I raised the idle speed on the carb.

    This weekend I noticed as I plowed longer (only my driveway and several neighbors) the plow got slower - to the point where it wouldn't move.

    My symptoms are as follows:
    1. When I take the plow off, I have to use come along to release chain, it will not drop even with me laying on it. This may be normal, but I don't know.
    2. Pump started whining for the first time yesterday.
    3. Have to really goose the gas to make it move once fully warmed.
    4. Colder truck (fluid) moves plow much faster - albeit still damn slow.
    5. Previously no problems with angle at all, now angle had similar issues with slow movement/ non-movement.

    I'm thinking pump all the way, but I'd prefer to troubleshoot to be sure. Is there any pressure adjustment on these? I do not have spare pumps, valves, or hoses!!

    I did change fluid this fall with new ATF.

    Thanks,
    Craig
     
  2. tractorbill

    tractorbill Member
    Messages: 65

    well sounds like the pump is weak.Make sure that your valve spools are centered when your control is in the middle.if they are I would try a pump. To be sure you can make a pressure guage from a extra coupler and a cheap pressure guage a couple 1/4 short pipe nipples and a tee.
     
  3. ColvinsPS

    ColvinsPS Member
    Messages: 73

    If you need a pump.. i have one for sale. If you have to go that route just pm me and we can compare model numbers.
     
  4. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    also drop issue . if the control lever is held in the float position and the ram cant be pushed down to release the lift chain you might have a bad lift ram. could need a rebuild or replace if realy rusty/junky on the inside.

    my old fisher speedcaster like yours lever in float/drop all i do is 1 hand on lift triangle and she bottoms out easy to release the lift chain.

    what fluid are you using ? those call for atf tranny fluid.

    and like said check the 2 cables at the flow valve for correct adjustment. if off a bit can let pressure blead off. and not work correctly.

    and get a hydro psi gauge and spare fitting for quick coupler to test pressure of system off pump . 1700-1800 if i recall correctly for good pump. its comon by now the pump will be worn out prob. but might get lucky and could be easy fix.
     
  5. ColvinsPS

    ColvinsPS Member
    Messages: 73

    Here are some pics for reference. Let me know if it looks right. I was asking $150 on CL but id sell it to you for $100 plus shipping if it will work for you.

    fisher pump1.jpg

    fisher pump2.jpg

    fisher pump3.jpg
     
  6. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    I run an old Speedcast plow with the underhood hydraulics, 1980s vintage, which I've refurbished. Hot fluid is less viscous than cold, so as your fluid warms up the pressure naturally will drop. But it sounds like in your case the pump is not putting out enough pressure to begin with, so when the fluid's cold it's adequate, but when the fluid warms up and thins out the pressure is no longer enough. New pump is most likely the solution. When was the last time you changed the filter (should be one on the low-pressure return line to the pump reservoir)?

    The packing on your lift ram may be a bit too tight. If it won't drop with your weight on it, I'd guess that might be the problem (your control lever in the cab is in the float position when you are doing that, right?). Try loosening it a little bit.

    No pressure adjustment. I would test the pump with a gauge and see what it's putting out. You can get a new pump for around $200 (I have part numbers if you need them).

    These belt-driven hydraulic systems are very, very reliable and rugged, just need to replace worn-out parts and then do a few simple annual maintenance tasks every year.
     
  7. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    Never, this will be the first thing I address most likely this weekend (when we are supposed to get a storm, of course.)


    Hmmm, I've read this here and I will check it out. The plow control is in the center (is that float?) or down.

    Thanks for the help.
     
  8. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    I'll let you know pending some troubleshooting this weekend.
     
  9. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    single lever joystick stick 2 cable system float is in the down position. it should hold there by its self. then when done with float just pop it to the middle position .
     
  10. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Make it an annual habit along with flushing out the old fluid.

    Center "locks" the lift ram in whatever position it's in, down allows the ram to fully collapse. When finished plowing, drop the blade by pushing the lever all the way down (you may have to manually push the lift arm to make the ram fully retract after the weight of the blade is on the ground). After you shut the motor off, toggle the lever back and forth between the angle right/left positions, to relieve any remaining pressure in the system, then store it in the float position.

    BTW, you may want to have some extra hoses on hand just in case you get a leak or blowout while plowing. I like to carry one of every size so I don't get caught with my pants down during a storm.

    Good luck--once you get your system overhauled, it should run great for you with just some basic preventive maintenance.
     
  11. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    this would be float position to let the lift ram close all the way. a lot of them wont drop by them self all the way. thay need a little help but you dont need a 5ft pry bar also to get the ram closed.

    and thats my 2hr custom flush mount joystick in my 73-87 style chevy truck.
    i love it so much better than factory fisher position.

    speedcaster hd 009.jpg
     
  12. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    OK, to clarify - when I drop the plow to remove it I keep the lever down - float position. This is how I do it now, just needing a lot more force to release the chain.

    And you are saying, to leave it in float when the plow is off the truck?

    Thanks
     
  13. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    I don't plow much, maybe a little over an hour max at a time. However, the location does suck, way too low - nice mod!
     
  14. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    If your lever is in the float position and the ram won't retract fully after you drop the plow to the ground, even when you push down on the lift arm, I would suspect either than your packing nut is a tad too tight or that your cable to the spool on the control valve that controls the lift ram is out of adjustment (easy fix).

    That's my preference. Not a big deal, but I like to relieve the pressure in the system when not in use (which is why I toggle the lever back and forth after shutting down--a trick taught to me by a Fisher rep) and leave the valve control "open" in the float so if there are any wild temperature swings (not likely) in the weather it won't build up any pressure. I've also taken to leaving it in float while driving down the road and let the carry chain hold the weight of the plow--saves a little wear on the lift cylinder.

    Before I started doing that, I went to remove a hose once when the system was pressurized (motor was off but I hadn't relieved the pressure), when I cracked it loose it squirted me good with ATF.
     
    Last edited: Jan 6, 2011
  15. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    Nice mod--I thought I was clever for chopping down the length of my stick and putting on a custom wooden knob (stock stick used to get my knee every time I got in and out of the cab!), but you've gone one better than that!

    Now let's have a look at the whole truck!
     
  16. ColvinsPS

    ColvinsPS Member
    Messages: 73

    No problem. It is just sitting on a shelf in the garage.

    Hopefully you can fix yours though. Good luck
     
  17. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    well i would post pics of the truck in this thread. but thay dont let you dubble post here.

    search my screen name i got tons of pics here .

    and i raised my seat in the truck almost 2" over stock as i felt like a inner city mexican in his low rider with the stock hight. now my knees are at a 45* from were i sit now. and i still have 2-3" from top of my head to roof of truck.

    and if i had mounted the controler stick in fisher spot it would be even worse for bangin my knee and i would also have to reach down to get to it. as it works now everything works as 1 big free flowing unit.

    i am in a nice hight in the cab with lifted seat. dont bang my knee on the control stick as its frenched in to the dash space. and i can rest my left hand on my left knee and the joy stick is right there perfectly. i can plow all day and only my butt is tired. all i did to mount was make a flat plate the same as the joystick front plate. and have it fit in the non used a/c duct hole. then pop off the fisher front plate and swap it with my custom one. then bolt it in the dash that easy. from start to full finish under 2hr. best 2hr i spent.

    and just so you dont think i am o.c.d. like this . . . . i planned non of this working so good. i swaped in some buckets and thay were 1" taller than the bench. and i mounted them on 1"x1" square tube thats welded to the stock bench seat sliders. then i figured french the contoler in the dash out of the way. and it worked perfectly.

    my truck might be a old A$$ 1979 chevy k30 but i have swaped in and on the best componets from 73-91 body style i could find for the best comfort and use and reliability. i think the best swap over part was the 1987 tbi fuel injection. no more carb.

    read my sig line for truck specs. and this summer its getting a major face lift. i have a spare 1ton frame thats in super shape. swapin the body over and the other goodys . then usin a 8ft box i have had that no one wants to buy ? its from texas and clean. then paint the whole truck black minus the roof and doors. thay will be white. Thumbs Up
     
    Last edited: Jan 6, 2011
  18. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    Filter?

    I don't have an in-line filter on the return line.

    Is there any filter internal to the pump?
     
  19. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    No. The inline filter is Fisher part# 8764. While putting one in won't fix your specific problem, it may help prevent problems in the future (along with annual flushes/fluid changes).
     
  20. c_nice_37

    c_nice_37 Junior Member
    Messages: 20

    Update

    I played with the plow a little this morning.

    I couldn't budge the packing nut on the lift ram - I was using a pipe wrench but didn't have access to a breaker bar. In any case, I lubed the hell out of it w/ Fluid Film. I can now move it with the weight of just my upper body. So I think this should be good to go.

    The valve was centered properly, unfortunately I was alone so I couldn't drop the truck in drive but by hand the speed seemed similar as using the joystick. I hooked it back up and it seems to be adequate. Again, no storm so my bet is this will happen again when I'm out for a while and the fluid gets nice and warm.

    My uncle works on hydraulics all the time, so when I get the time I am going to ask him to pressure test the pump for me.

    Thanks guys, and I'll be sure to post the ultimate findings.