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Older Fisher Under Hood Hydraulics running slow???

Discussion in 'Commercial Snow Removal' started by westernmdlawn, Jan 20, 2004.

  1. westernmdlawn

    westernmdlawn Member
    Messages: 39

    Hi All ! Hope everyone is doing well. I have an older Fisher plow with all under hood hydraulics. The truck is an 89 F-250 HD. The hydraulics are sorta slow for my tastes. For example it takes approximately 5 or more seconds for the plow to raise all the way up from the ground. Same for the angle cylinders. These figures are with the engine at idle, which is probably around 750 RPMs. I was thinking of overdriving the pump by putting a smaller pulley on the pump and getting a shorter belt to suit it. This would increase the rpms of the pump while at idle. Right now the pulley system is 1 to 1, in other words the drive and driven pullies are the same diameter. The engine does not bog down at all when activating the hydraulics at idle, so I think that there is plenty of torque available at idle to overdrive the pump. The only question is what about when the engine is at higher rpms and you activate the hydraulics, then the hydraulics will move super fast. Could this be detrimental to the system components? Basically, the higher pump rpms will result in an increased flow rate and decreased available pressure (to some extent). Just wanted to hear some opinions from you all. Thanks in advance!
  2. bgingras

    bgingras Senior Member
    Messages: 282

    It stems from a warn plow pump or compnents, I have the same problem, and just havn't getten around to replaceing the pump. Since my plow truck is a standard, I simply stay on the clutch an extra second or 2 and rev to lift and then back up...works fine for now.

    I've been told it will get worse over time, and will need to be replaced eventually.
  3. Bolts Indus.

    Bolts Indus. PlowSite.com Addict
    Messages: 1,176

    If you change the gear ratio you will blow the pump at highway speeds. Drove one like that for years, just give the revs in between shifts,that's what I did. They were all like that,even when new.
  4. foyboy41

    foyboy41 Member
    Messages: 38

    plow pump

    not to sound pushy but i have a fisher conventional under hood for sale on the other forum the pump is only one season old it came off a ford but the bracket can be changed to fit any truck with any motor also have controls $200.00 takes it i bought a new fenner thanks JOHN........
  5. wirenut

    wirenut Senior Member
    from nh
    Messages: 529

    what you do is cut the back off the tank pull the pump and have
    the the 2 halfs resurfaced.whats happening is the gears and body have play and fluid is bypassing cheaper than buying..have
    on the shelf. buy the way i run a 3" pully on mine never had a
    problem but then i dont drive but 60-65 in the truck anyway.
    hope this helps:drinkup:
  6. westernmdlawn

    westernmdlawn Member
    Messages: 39

    Hi Guys... Thanks for all the good info. The pump is not worn or malfunctioning, it was just designed this way. I know there is no fluid bypassing the surfaces, it is just not cranking out a huge flow at low rpms. I know it is functioning properly because I checked into that. I put the plow control stick so that it would stay in the raise position while I crawled under the hood. Then, with the belt off, I turned the pump pulley by hand in the correct direction and sure enough, the lift cylinder began to actuate. After about 20 or so rotations and the blade up off the ground a little, I let my hand off of the pulley and the weight of the plow pushed the cylinder back down (since the control was still in the "raise" position) and made the pump turn in the opposite direction. In other words, doesn't seem to be running incorrectly.
  7. jt5019

    jt5019 Senior Member
    Messages: 853

    Mine is the same way on my 90 ford. I just rev the engine a little when im lifting the plow and it speeds it up a bit.
  8. westernmdlawn

    westernmdlawn Member
    Messages: 39

    Yeah.. that definitely works I know, but the problem is that mine is an automatic, so I'm usually in gear while moving the plow. :dizzy:
  9. skmodmsl

    skmodmsl Member
    Messages: 43

    I have the old style pump driven Fisher setup too. It is slow at idle. I too push in the clutch and rev the engine a little to raise the plow. I noticed however that the pump is noisy. Also as the day goes on the plow gets a little slower.
  10. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Well at least you ain't at the mercy of an electrical driven pump. Just rev the engine and you have movement of the plow. I got to watch my battery voltage at all time.
  11. GripTruk

    GripTruk Senior Member
    Messages: 374

    I almost posted a new thread... glad I searched first.
    I have an old Meyer hydraulic setup in my Jeep, and at this point, it wont even go up at idle speed. What can I do to check/tune up the pump?
    I was considering changing to a different size pulley. Anyone know what to ask for? You know how it is at auto parts places ..."What kind of car,? what year?" that's all they want to hear, you say "I want a pulley with a shaft like this, but smaller", and they won't be able to do a thing.

  12. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Did it go up at idle before? don't know much about engine driven but maybe it has a filter screen in there somewhere that needs cleaned.
    or the pump might just be getting tired.
  13. GripTruk

    GripTruk Senior Member
    Messages: 374

    Well, I spent about 12 hours today swapping pulleys and such. I got a pulley we had lying around with two grooves the same size, about 5 inch diameter. The old pulley on the power steering pump was about the same diameter, but had a smaller pulley, about 3 inches, on the front. I replaced the power steering pullley with the new one, and put the power steering pulley on the hydraulic pump. So, instead of a 3 going to a 5, it is now a 5 going to a 3. It is A LOT faster, like, it went from, barely moving to pretty fast. I really have no way of telling what shape the pump is in, but it's working as of now... If I can find out what kind of pump it is, I'll get a spare.

    The only issue, (Besides the hours spend modifying the brackets to accomodate the differences in offset of the pulleys) is that when I angle left it goes really quick, but when I angle right, it feels like it's fighting something.
    I'm going to have to look at it tomorrow, but if anyone has a guess, I'd love to hear.