John Deere 420 hydro pump
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Thread: John Deere 420 hydro pump

  1. #1
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    John Deere 420 hydro pump

    how can I take my 420 hydro pump out of my 420 with out pulling my engine of transmission??
    Andrew

    1973 110,
    1972 110,
    1973 110,

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    1988 420,
    1981 400,

    1976 300,

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    Display Name: Cliff H
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    You could cut the driveshaft. Seriously though, the engine or transmission need to move. My usual technique is to slide the engine forward a bit by removing the motor mount bolts, and removing the bolts holding the driveshaft onto the engine. With or without tilting the engine a bit for more room, I can usually get the driveshaft to slide off the hydro pump.

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    Display Name: Doug Cartwright

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    I like Cliff's advice. Is your hydro bad,or just leaky?

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    From another post/forum, OP believes pump is bad.

    A word of caution on reassembling: Everything MUST be 110% clean, operating room clean! A piece of debris that's .0005" to .002" can destroy your new pump, valves, cylinders! Dirt/debris in a hydraulic system means instant death to the unit. Bob
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    Bob is 110% correct. I spent about 9 months working for a Caterpillar dealer rebuilding pumps and motors. That shop was ridiculously clean. No windows. I would eat lunch and take breaks in the bed of my truck to soak up some sun. I left there and went to do construction. I’m a flower I guess...I wilt without sunlight On a side note, their paint is amazing! Only paint I’ve ever seen that doesn’t fisheye on grease or oil, and it sticks to grease!
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    Quote Originally Posted by doug_cartwright View Post
    I like Cliff's advice. Is your hydro bad,or just leaky?
    I got it out!!! thanks for your help I'm just replacing the seal that goes around the drive shaft.
    Andrew

    1973 110,
    1972 110,
    1973 110,

    1969 112,

    1988 420,
    1981 400,

    1976 300,

    1987 160,

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    doug_cartwright (02-10-2020)

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    AHH! Whole different story! That's called a charge pump. Drop drive shaft, take 2 bolts out...or pry seal out... and you're home free!

    Another word of caution about messing with the charge pump. There's a small, maybe 1/8" dia., pin that drives the gerotor...a kind of gear looking part inside the pump... and MANY people have dropped this without knowing it was even there! Unless you're 100% positive it's in place, dismantle and check.

    Clean all debris/rust from drive shaft yoke where it slides through the seal. Check end of drive shaft for a wear groove. If worn, you may have to replace yoke or still end up with a leak! Lube shaft & seal with oil before reassembling. Bob
    '80 317 w/18hp B&S and divert valve for rear hydraulics, 3 pt hitch, 5' york rake
    '82 314 w/rear PTO for tiller
    33 tiller
    49 thrower
    54 4 way blade
    Mod 48 deck & Mod 462 TracVac

  11. #8
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    okay, the pin is still there (I watched a you tube video before I replaced it and he mentioned the pin) I had too pull the hole thing the charge pump is on to replace the seal be cause of how my tractor is.
    Andrew

    1973 110,
    1972 110,
    1973 110,

    1969 112,

    1988 420,
    1981 400,

    1976 300,

    1987 160,

  12. #9
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    I got my new filter for my 420 Hydro today and I was wondering is there any thing I need too Do other then change the filter and refill my transmission with oil? if I do it that way will it air lock?
    Andrew

    1973 110,
    1972 110,
    1973 110,

    1969 112,

    1988 420,
    1981 400,

    1976 300,

    1987 160,

  13. #10
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    Display Name: Doug Cartwright

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    Andy,check out the last post on page 3 of this thread... https://www.wfmachines.com/forums/sh...light=bleeding

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