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hydraulics respond well cold, lousy hot

Discussion in 'Truck & Equipment Repair' started by archibaldtuttle, Jan 27, 2011.

  1. archibaldtuttle

    archibaldtuttle Junior Member
    Messages: 5

    This is a mish mash plow set-up so I don't know whose pump it is. the plow is a western but it's not mounted on a western mount. I trust that the question on hydraulics wouldn't be brand specific.

    The pump is belt driven, mounted on engine.

    When the hydraulic pump is cold it lifts the blade just fine at maybe a 2500 RMs, i.e. not much over idle, but the longer I run the truck the more RPMs are necessary to lift the plow.

    Side to side is equally affected but because you're not fighting gravity I don't have to cook it up to 4 thou to get the thing angle.

    I'm wondering if this could indicate that the hydraulic fluid is thinning out, or maybe has some water in it or . . . ?

    There aren't any signs of glazing on the belt and it never squeals or leads me to believe the belt is slipping.

    I can see if I can find a pump manufacturer when I'm at work tomorrow if that makes any difference.

    Thanks,

    Brian
     
  2. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Pump is worn out.
     
  3. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    i concur with lassie. pump is going out. the pump is probably a fisher set up.
     
  4. LON

    LON Senior Member
    Messages: 749

    I agree. See it quite often.
     
  5. archibaldtuttle

    archibaldtuttle Junior Member
    Messages: 5

    wouldn't surprise me

    wouldn't surprise me in the least that this pump is a beater.

    I'm just wondering why it works so well when its cold and whether putting heavier oil or some oil additive or multigrade oil, if hydraulic is available that way, might be a stop gap while I look for another pump, and/or figure out who can rebuild the one I've got.

    Brian
     
  6. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    what do you run for oil now? atf is a lot thicker at low temp than most plow oil. i have heard of guys running 10 w 40 as a last resort.
     
  7. LON

    LON Senior Member
    Messages: 749

    You could run 80/90W in it and as soon as it got hot enough it too would break down. Only going to be a band-aid fix.
     
  8. archibaldtuttle

    archibaldtuttle Junior Member
    Messages: 5

    ATF . . .Alcohol, Tobacco, and Fluid?

    someone even recommended gear oil if I'm reading right.

    Now I always had this impression that hydraulic oil was not only a lighter oil than most motor oils but was specifically excluded some part of the hydrocarbon spectrum that would attack rubber seals. So ATF never worried me much that being essentially a hydraulic medium and the crossover between transmission fluid and hyrdaulics being pretty much complete in heavy equipment. But are there oils I should avoid. Obviously something that can maintain a serious multigrade standard would seem to be helpful. Maybe a synthetic.

    I think there is a fair amount of ATF in this mix currently (its red). So I assume the drop off in performance is related to the thinning of the oil and loss of tolerance in the pump. I do think the mount is a Fisher, so maybe the pump and the mount came together. There was no plow on the truck and I got a western out of junkyard and cut the mount on one side and moved it over and inch to match. Any way to identify the pump so I can spec a replacement. (e.g. appearance, model stickers, secret nos, etc. I assume they rebuild these. I can check with a local supplier for a rebuilt once I figure out what pump I've got and keep the whole process honest by checking in on the internet.

    It probably will turn out that a replacement is fairly inexpensive and readily available so I may be overthinking this oil thing, but it sounds like the day it won't pick the plow up if I haven't gotten one, I should have some heavy stuff on hand.

    thanks,


    brian