International harvester 633 question

Hey guys Im not to tractors and this is my first machine

The loader and bucket stopped working and Im wondering if I could get some help. It always the Loader control valance is connected to an auxiliary valve thats held in the down position by a spring / bungee it was working fine and then just stopped working totally. Does anyone here know how to test that auxiliary control valve ? Or how I can start figuring out what could have happens?

If you are talking about the remote couplers in the back you could put a gauge on a coupler tip and plug in then pull lever to see if you get any pressure. If no pressure you have probably found your problem. Which could be one of several things. I would first start with a filter change and full oil level. Then if no better, look into having somebody with a flow rater check it as you are at that point then. You need to know if when you have pressure how much volume you have at that pressure, and the only way to know is a flow rater. You can pull the pump and check if the nut let the gear fall off and those types of things and get lucky and fix it that way. IT looks to be a similar model to the 74series which has one pump for the hydraulics and it runs everything from the MCV or (multiple control valve) which should be on the left side under your left foot about . IT will be there with a few lines coming off from it. Filter should be bolted to the side of it. 1 bolt will get it off has a steel cover looks something like a grain bin there will be the filter and a screen wash the screen out before you put the filter and screen back in. I usually don't worry about changing the square o-ring under the canister since it is a pain to dig out. If not leaking no sense in changing it. Don't over tighten and crush the canister or it can/will leak and then need replacing.

Way back in the late 1970s a neighbor had an IH 633 4WD and I am going by my 75 year old memory but I believe the tractor was built in the IH plant in Neuss Germany and the only common component to the IH 54/74 series tractors was the IH Neuss D-179 Diesel engine, this is sort of confirmed by Tractordata.com. I do remember from the clutch housing rearward the transmission and differential appear to be a modified IH Bradford, UK design much like a B414/434 of the time. The hydraulic system was run off a hydraulic pump mounted on the right front of the engine and there was a filter on the pressure side of the hydraulic pump mounted on the right side of the engine by the clutch housing before the engine oil filter.
If you don't have a service manual now is a good time to buy one as they are available on the internet.
Some questions:
1) Have you checked the hydraulic oil level?
2) Does the 3pt hitch work?
3) If you move and hold the Aux control valve in the apposite direction will the loader work, the loader control valves should work in the opposite direction now?
4) Is the loader connected to the Aux valve outlets with hydraulic Quick Couplers? If so make sure the Quick couplers are seated properly.
5) I don't know if the Aux valve on this tractor is live all the time or if there is a valve that has to be closed like the B414/434 series tractors.
6) Is there also a suction filter besides the pressure filter in the hydraulic system?

Like I said I am going by the things I remember about the neighbor's tractor and he only kept it for a few years and traded on a larger tractor.

Hello ..me.. welcome to YT! I hope I am correct and excuse me if I am wrong but I get the feeling cat guy may have dove into this at a level a bit above where you are at. First let me say I am not real familiar with the IH utility models and far less familiar with the British built ones such as you have. Do you know where the hydraulic fluid level is checked? If so I can only hope you have checked it. If not that is where I would start. I am going to surmise that this tractor uses the transmission and drive housing as the reservoir for the hydraulics so that the hydraulic fluid is also the gear lube. I am going to take a huge guess that plug number 9 on the back of the tractor is where the level is checked, see link. Maybe it has an actual dipstick somewhere along the sides of the housing in the area your lower legs are when you are setting on it.
I am going to do something I rarely do, I see YT does not offer the Operators Manual for your tractor I am going to give you a link to a PDF version for purchase. That manual will be invaluable towards operating and maintaining your tractor.
Pictures of the hydraulic pump and lines on the side of the engine-tractor may also be helpful.
CNHI IH 633 online parts catalog diagram

Down loadable manual

Thank you for the replies Im so grateful there is a community out there for this

1) Have you checked the hydraulic oil level?
- yes looks to be at the right level

2) Does the 3pt hitch work?
- yes 3pt still works

3) If you move and hold the Aux control valve in the apposite direction will the loader work, the loader control valves should work in the opposite direction now?
- no when I hold it opposite nothing happens (sounds like a release valve opens when I do)

4) Is the loader connected to the Aux valve outlets with hydraulic Quick Couplers? If so make sure the Quick couplers are seated properly.
- I will check this next

5) I don't know if the Aux valve on this tractor is live all the time or if there is a valve that has to be closed like the B414/434 series tractors.
- wish I knew the answer to this one


6) Is there also a suction filter besides the pressure filter in the hydraulic system?
- I will have a look when it stops raining cats and dogs here today

The photo below is the control valve for the loader and bucket tilt - it have two lines coming from that auxiliary valve being held down by bungees (the loader was working until I pulled backwards on that bungeed down lever ) is it possible I pulled all the hydraulic fluid out of this secondary circuit when I pulled back in that lever? Would it be possible to swap out the quick connects and see if I push fluid back in?

I will do a full hydraulic flush and order a new hydraulic filter next + purchase the service manual for this machine as soon as I can find one.

Thanks again.

I will see if I can borrow a pressure tester from my neighbour and test the pressure to see if its getting anything - so strange it was working great until I pulled back on that bungeed lever. Is it possible I pulled fluid out of the secondary system when I pulled back on that lever. I will start with pressure testing the lines and go from there.

Likely unknown to the original poster for reasons to in depth to explain here this forum also exists in a somewhat ..parallel universe.. called ..Classic View.. that is where I view and post to this forum. Sometimes certain ..triggers.. come up that do not allow the two forums to sync. In this case I am sure it has to do with a link I posted. Even though Jim covered most everything I had, I am going to link the Classic View here so you are aware of the links I posted.
My apologies to meehowsnow for any confusion.
https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=ttalk&th=2424506

That is a standard loader control valve setup for that vintage of IH tractor. We had the same one on IH 434 and 384. Since the last thing you did was pull the Aux Control vale lever up and everything stopped working for the loader and when you pull the Aux control valve lever in opposite direction you hear like a relief valve opening then I wonder if the Aux Valve had been sitting in the one position for so many years and you moved it that an O-ring on the valve spool hasn't broken and is either plugging a hydraulic orifice or preventing the spool from going back to the forward position.
First check the Quick couplers connected to the Aux Valve outlets.

Re Service Manual, Used red MN posted a link to parts manual and if you scroll down the Service Manual is there as well.

I see you have replied since my Classic and Modern view situation occurred. If a coupler has become incorrectly connected then the same result should happen when the lever is held the direction you normally had it bungeed, it should open the bypass valve as it does when you moved it the opposite direction. If it is not doing that I would simply suggest swapping the hoses in the remote one to the other and retry moving the lever the opposite way to see if that will make it work. If the hydraulics went into bypass and loaded the engine slightly when you moved the lever the other direction that is telling me the hydraulics are capable of building at least some pressure.
You said.. is it possible I pulled all the hydraulic fluid out of this secondary circuit when I pulled back in that lever?.. The valve and loader really have no ..reserve.. of fluid other than what is in them to perform their functions. So no you did not ..suck it dry.. so to speak. By having that valve bungeed in position which is a common method you are directing oil to loop through the hoses and valve, which is by the way is an ..open center.. system. When you move a lever on the loader valve you simply direct the flow into the cylinders at the proper ends to get them to extend or retract. The valve at the same time opens the opposite line of the cylinder to the return hose so it can exhaust fluid. When you release the lever and the spool centers the fluid is blocked from entering or exiting the cylinders and the pressure oil from the tractor just returns to making a loop. Since liquid cannot be compressed the fluid ..blocked.. inside the cylinders holds them locked into position unable to extend or retract.
If reversing the hoses and direction of the valve make it work something has failed inside the tractors valve.

Hey Jim - so when I hold the aux control in reverse the loader hesitates moves a little then I release the aux valve and the loader moves a little again in the core t direction.

This is the same for bucket tilt .

Hey sorry not sure how to keep things in modern/classic view
hahah - its worked I reversed the couplers in the aux valve
pinned the handle to the opposite side it was bungeed to
originally and all systems are functioning correctly. Wow Ive
learned so much through this process and talking with you guys.
Thank you so much for the suggestions and ideas. I still have a
long way to go to make this a tractor I can use without issues
but step one is a good one. Thanks again

That workaround points to a problem with the auxiliary valve. It may require removal and disassembly of the valve to determine what is going on. Or it may work perfectly fine the next time you try it.

The loader valve won't work with the hydraulic flow running backwards through it, which is why it made funny noises when you moved the aux lever in the other direction, AND why you had to reverse the hoses to make it work.

You are very welcome, good to hear it is functional again.