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Thread: international 434 hydraulics - sudden fail - help!

  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

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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.

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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

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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

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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.
    The best thing about Facebook is the logout button......

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    Re: international 434 hydraulics - sudden fail - help!

    Quote Originally Posted by Footsfitter View Post
    Hi Roger,

    Firstly.. sincere thanks for getting back - appreciate It!



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

    Yes, indeed, thats the one - the lifting controls are different and there are two extra control valves because it is the 'vari-lift' model
    but basically the same




    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?

    Right again.. cleaned No3 and, as far as I can tell, no leak in the joiner hose

    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.
    No sign of oil weeping out there

    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?
    I've only examined the pump externally -and all looks OK but guess i need to take it off and check....

    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.
    I drained and re-filled with Hy-trans which, from what i could glean from the web was the right oil. Its the big bubbles that worried me more than the foam..

    You asked

    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.
    Aaaahhh! - thats reassuring


    So... next job... remove pump and check for wear and leaks..
    and.. If you can suffer just a couple more questions?
    Would a lot of air in the system cause 'complete' failure of the lift or should you be able to detect maybe a small effort to move the piston?
    There is a pressure release valve identified within the control valve assembly - does this ever stick open? (I guess the answer is take it apart and check !

    Again - thanks for your time and info - its a great old workhorse of a tractor that has suffered a little neglect and I really want it up and running again
    cheers
    roger

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    Re: international 434 hydraulics - sudden fail - help!

    The sudden failure makes me think some thing has broken or detached.

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    Re: international 434 hydraulics - sudden fail - help!

    well --- i'm happy --- very happy ! -- but i don't know why...
    so just to finish the thread - its always good to know what happens
    ok.. so I topped up initially.. no good
    drained and cleaned suction filter - refilled - no good
    drained - replace suction filter with a new one, cleaned orifice filter and speed control valve (the one on the left)
    ( was hoping i could remove the control valve on the right to clean but couldn't get it out - not sure if it does come out by undoing the two nuts?)
    refilled - still no good
    Couldn't 'see' anything wrong with pump - seemed to be pumping ok but didn't have anyway of testing with gauge - but had been lent an old one to try
    drained a couple more times - taking inspection cover off as before - looked inside and scratched head a few times
    then repeated above...
    Thought i might have to lift casing (looks heavy) and look inside incase relief valve maybe stuck open?
    repeated above one more time - just in case -- and joy... it just started working !
    I have no idea why - maybe something stuck and then suddenly freed - who knows
    but i'm happy.......

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