3pt hitch goes up and down but will not maintain a position when stopped it goes back up

camfire

New User
Hi all new to this forum and to tractors and have been watching and reading for awhile- but im getting a crash course in internationals in the past 3 weeks- i purchased a 1966 international 434 desiel its a little rough but have slowly been going thru different parts of tractor in hopes of cleaning it up- ive done oil change and filter aswell as drained hydraulics and replaced o rings in both isolator valve and speed flow valve as they were leaking heavily - the tractor has a loader with controls and rear remotes with a single spool valve for rear- hydraulics seem to to be working except for the issue with 3 pt hitch it goes up and down with spool controls but when i release it just goes back in the up position - i have isolator valve open and side lever in forward position as per manual but still does not stop unless i get to desired 3pt hitch position and shut isolator valve then it holds position but just doesnt seem right- if im missing something if theres anyone out there more familiar with 434s it be great to hear from you or any suggestions would be greatly appreciated.
 
Does it have an add-on spool for the rear remote , or is it the factory valve mounted on the top rear end cover?
Was it doing any of this before you changed the o-rings?
Make sure the position control (short lever with square red knob, next to lift lever) is not seized, try moving this lever around and see if it changes the symptoms.
 
Be careful closing that isolator valve and operating the controls because in certain positions they close off the hydraulic flow and the system goes over relief. You can tell by the noticeable drop in engine rpm and the squealing or hissing of the relief valve.
 
Thanks for reply Fritz- yes it had same symptoms before i changed o rings out was hoping that was the issue but no luck and yes it does have an add on spool for rear remote which i was thinking perhaps the issue is bad spool but it does seem to raise and lower 3pt hitch just when i release spool lever 3pt hitch rises back up to start position.
 
Ive also tried lever it appears to move and function as normal and not seized but ive tried various positions but if lever not in forward (lower) position the 3pt hitch will not move with add on spool.
 
I do hear a buzzing sound coming from suction tube filter line aswell when i activate add on spool but i have already replaced suction tube filter aswell because it did not have a filter attached from previous owner not sure how long it was like that so i replaced it -
 
Does the lever just move to a different position when you let it go? If so it is likely parts 5, 7 & 8 are part of what holds the lever in position when working correctly. CNHI IH 434 parts diagram Otherwise, if this has been a problem as long as you have had the tractor then something is probably about the external valve is not connected correctly.
 
Hi red MN- no the add on remote spool is what is used to raise and lower 3pt hitch but when i release spool the 3 pt hitch rises back up on its own- the lever control your refering to seems to slide fine and allows spool to raise and lower hitch if lever is in full forward position.
 
I am new to hydraulics and to tractors i understand by reading manual that isolator vaive should be open and originally hydraulic levers on right side of driver would control the raising and lowering of 3pt hitch- in my case previous owner added a spool to control rear remotes so now spool controls 3pt hitch which it does up and down but raises back up once spool is released so not entirely sure how that works because by doing so it has rendered original hydraulic control levers basically non functional- or am i missing something
 
Will the 3 point arms lift any weight when they raise up like that? Even just someone standing on them? I am no expert on the hydraulics on those machines but I am going to say whatever was added on is not plumbed correctly.
 
Without seeing it, a guess would be that the hitch control lever is not actually moving the valve inside the top cover, whether the splines be stripped or some other damage to the control shaft. The valve is currently in the ‘raise’ position, and for some reason the return oil from the priority valve in neutral is not being returned to the sump, but directed into the hitch lift cylinder. Why you can drop the hitch with the priority valve is a curiosity to me; there is no place for the oil to go, whether or not you have a cylinder hooked to it.
Sounds like your problem lies under the rear end cover.
 
Thanks for replies-(used red MN)the 3pt hitch will lift weight when raised or lowered not sure if plumbed properly my guess the spool wasnt returning back to neutral.
Fritz Maurer- i kind of understand what your saying that it could be something under cover- if i remove cover can i run engine without oil spilling out ?When you refer to "valve "being in raise position which valve are you refering to? Aswell as "priority valve"?which ones are they and where are they located?
 
Thanks for replies-(used red MN)the 3pt hitch will lift weight when raised or lowered not sure if plumbed properly my guess the spool wasnt returning back to neutral.
Fritz Maurer- i kind of understand what your saying that it could be something under cover- if i remove cover can i run engine without oil spilling out ?When you refer to "valve "being in raise position which valve are you refering to? Aswell as "priority valve"?which ones are they and where are they located?
The priority valve is the valve that runs the remote cylinder. It gets priority over the 3 point hitch because the oil flows this valve first on its way to the 3 point hitch valve; the priority valve will operate first when the 3 point hitch and priority valves are operated simultaneously.
The valve that operates the 3point hitch is under the top cover, which also serves as the reservoir. The hydraulic oil is separate from the trans/rear end oil.
The engine cannot be run , rather, hydraulic action cannot be observed, with the top cover off… you have to get a shop manual and take the thing apart.
This is assuming that the problem is actually under the cover… as I stated in the beginning without seeing it , this is just a guess. Need someone on site who knows what he’s looking at to accurately troubleshoot.
 
I understand hard to tell without seeing how its plumbed or what should or should not be on or off - something definetly is not right loader double spool feeds single spool located below it they both work at same time flow travels to loader and 3pt hitch which explains why both are very slow they seem to be sharing same simultaneously- there seems to be no way to stop flow from front to back unless i shut isolator valve but then that stops flow to both loader and 3pt hitch- i was almost thinking if it would simplify things if i eliminate 3pt hitch spool and just return to factory lever controls for 3pt hitch and just leave loader on its own?
 
Could you please post some photos of the hydraulic plumbing on your IH 434, so we can give some advice.
Also photo of the top link at the rear of the seat where the chrome draft sensor rod comes out of the hydraulic housing and touches the top link pin assembly.

Thanks
JimB
 
Hi i have attached some pictures hope this helps i can add aswell that when i lower or raise 3pt hitch using spool control there is no resistance i can stop lift arms with my hands loader seems to lift .
 

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And there is still a buzzing sound from suction tube which at first thought it maybe a clogged filter but later discovered there was no filter at all so i have replaced aswell as fresh hydraulic fluid
 
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