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Thread: international 434 hydraulics - sudden fail - help!

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  1. #1
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    international 434 hydraulics - sudden fail - help!

    Firstly - new to the forum (and to tractors!) so please forgive me for any breaches of etiquette - thx
    Old 434 - lifting arms working fine then, suddenly cease to lift.
    Plan to check out suction filter first (1st idiot question - do i have to drain the hydraulic fluid before removing the filter?) in case no oil getting to the pump
    but should have said - in addition to not lifting - you can raise the arms by hand (even if control valve on right side of seat is shut) is that right?
    2nd question - is there an easy way to check if pump is working ok? (I only have basic tools - no pressure gauges etc) or any other checks i can do?
    3rd question - is there any sort of pressure release valve in these that could be stuck open?
    Oil is low and somewhat grey and tractor not been serviced since acquired by present owner (7/8 years... i know... i know...)
    thanks for any suggestions and help
    roger

  2. #2
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    Re: international 434 hydraulics - sudden fail - help!

    "Oil is low and somewhat grey"?

    Low oil would make the arms not work - if you don't see any major leaks, it was probably working "barely" until it went too low.

    "Somewhat grey" sounds like some water got into the system

    I suggest draining and refilling with the proper fluid.

  3. #3
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    Re: international 434 hydraulics - sudden fail - help!

    thanks ironhead - will do...check the obvious first i guess

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    Re: international 434 hydraulics - sudden fail - help!

    drained.... cleaned suction & orifice filters - refilled with clean
    still the same

    took inspection cover / top plate off when it was empty and could see nothing odd

    question... anybody know if i can remove the main control valve assembly to check it (whilst the heavy hydraulic casing is in situ)
    and get it back together again !! ??
    thanks for your time....
    roger

  5. #5
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    Re: international 434 hydraulics - sudden fail - help!

    ok... as i said... drained dirty fluid. cleaned suction & oriface filters & re-filled with new fluid - no different
    Someone suggested i remove the inspection cover and look at the fluid when the engine is running - would help to indicate thatthepump was working - to a degree...
    Did that.... hmmm..lots (lots!) of air bubbles appearing
    I'm right in assuming that air can only enter in the suction 'section' yes?
    so removed suction filter (again) and checked suction line for leaks (couldn't see any)
    re-assembled and its still the same - no action from the lift at all and lots of bubbles appearing in the fluid..
    any thoughts anyone?
    thanks
    roger

  6. #6
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    Re: international 434 hydraulics - sudden fail - help!

    Quote Originally Posted by rogerds View Post
    Firstly - new to the forum (and to tractors!) so please forgive me for any breaches of etiquette - thx
    Old 434 - lifting arms working fine then, suddenly cease to lift.
    Plan to check out suction filter first (1st idiot question - do i have to drain the hydraulic fluid before removing the filter?) in case no oil getting to the pump
    but should have said - in addition to not lifting - you can raise the arms by hand (even if control valve on right side of seat is shut) is that right?
    2nd question - is there an easy way to check if pump is working ok? (I only have basic tools - no pressure gauges etc) or any other checks i can do?
    3rd question - is there any sort of pressure release valve in these that could be stuck open?
    Oil is low and somewhat grey and tractor not been serviced since acquired by present owner (7/8 years... i know... i know...)
    thanks for any suggestions and help
    roger
    Quote Originally Posted by rogerds View Post
    ok... as i said... drained dirty fluid. cleaned suction & oriface filters & re-filled with new fluid - no different
    Someone suggested i remove the inspection cover and look at the fluid when the engine is running - would help to indicate thatthepump was working - to a degree...
    Did that.... hmmm..lots (lots!) of air bubbles appearing
    I'm right in assuming that air can only enter in the suction 'section' yes?
    so removed suction filter (again) and checked suction line for leaks (couldn't see any)
    re-assembled and its still the same - no action from the lift at all and lots of bubbles appearing in the fluid..
    any thoughts anyone?
    thanks
    roger
    Hi Roger,

    Not sure if this will help but the only time I have fiddled with one of these was one we had with a front mounted road brush at the plant hire firm I did my apprenticeship with in '76-'81!!

    Having found the model on the CNH parts website do these look like what you have?




    It looks like I remember with an engine driven pump up the front. I assume the filter you have cleaned is No3 in the RH picture? - is there a leak in the suction pipe joiner hose No2?

    Going back to the LH image, is there any signs of oil weeping from the suction tube up to the pump? Small weeps can happen where there is a wee pinprick or chafe when stopped, when running it may allow air in. Next thought is with the pump itself, has it sheared a drive key between the shaft and gear that drives it? Is it so worn that it is cavitating- could be wear between the internal gears and the housing or if there is a lot of wear and the shaft seal in the front of the pump housing is hard/cracked could allow air in to the suction side of the pump?

    Trouble is the foaming you have seen may be acceptable as oil tends to do this especially when cold or if it old and/or the wrong grade, but you could be right in that it is excessive.


    You asked

    "in addition to not lifting - you can raise the arms by hand (even if control valve on right side of seat is shut) is that right?"
    Most tractors with the old fashioned internal lift cylinder usually have a single acting piston in a barrel that pushes on a push rod connected to the lift cross shaft, the weight of the arms and linkage usually holds the rod in the pistons underside, your action of lifting the arms has simply lifted everything except the piston that is sat in the bottom of the cylinder, when you let the arms back down the rod will slide its self up into the tapered underside of the ram.
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