SOS, I have my first tractor problem, Hydraulic lift issue

[JC-jetro]

Well, I encountered my first tractor problem. I’m starting to get my ducks in a row and fix the problem. Would greatly appreciate input from of more learned and experienced folks. Just a quick history, I bought a 1979 Ford-1700, 2 cylinder Diesel engine with no mechanical issues evident to me at the time of purchase. Single lever 3-point hydraulic system worked perfectly, engine purred with no smoke and plenty of power. I had it in the back yard for 1 month, looked it over, changed all fluids but hydraulic and identified the components and lubed it up good. A buddy helped me hauling it to my acreage; I ran it for the total of 8 hours in 3 sessions. The problem I had was with hydraulic lift system deciding to quit on me for some reason. The only thing worth noting prior to incident was this. I raised the 3 point as high as I could with a heavy carry all attached to it with some lumber on and a bottom buster before I came down the trailer ramp, when I came down I kind of heard an abnormal noise kind of synched with engine RPM, It appeared like some grinding noise same as throw out bearing in a clutch system that is constantly touching the finger on the pressure plate, I stopped the engine and thru a hand hole/peep hole on the right side of trany was able to see the bearing and it was not touching the pressure plate, I had plenty of oil in the crank case and engine lights were also happy. I started the tractor and more of the same, I’m kind of upset by now and can not figure it out the problem, any how I drive about a mile and haul some cinder block to my newly designed deer blind (some people call it “The Ritz”), after one hour only by accident I notice a bit of vibration on Hydraulic discharge pipe going to the lift cylinder , I lowered the 3-point hitch and sure enough the noise disappeared promptly, I then adjusted the lift handle so I can not push it beyond that point and I thought I was done. since then lift gradually started to act squirrelly as would not go up and down as quickly or when I wanted it and sometime would come up during tractor move and putting the engine in higher rpm would not make much difference. Last Friday I had a hard time raising the lift, eventually it came up, put all my stuff on it and headed where I was planning to clean up brush, put some clay block on carry all and then it totally quit. I have done the following to remedy the situation.

1. Looked for any sign of fluid loss and found nothing.
2. Took the dip stick out and looked in, since I did not have flash light it just appeared to me that my transmission is totally empty, dropped all , made a trek to my Jeep in the woods, hauled my self back to town ,went home and took some hydraulic fluid. When I came back I put some in and then and looked at the dip stick, had flash light now and just realized I over filled the transmission housing by ¾”. Started the tractor and 3 point hitch very grudgingly came up and in two minute change its mind and decide to come done. By this time it was 3:30 pm and I started the day @ 7:30 am and still was chasing my own tail, so I took the carry all off, left it in the filed ,cleaned up and parked the tractor at my neighbors barn about ¾ mile away.

Now these are the thing I plan to do to correct the problem. Please advise in light of all the stuff I had to say, I apologize if I were lengthy, I could not explain it in a more of a condensed format and though background info might help.

1. Bought O-ring set and gasket to remove hydraulic suction piping from the pump after I remove the right rear wheel to inspect the inlet screen. I hope the screen is clogged causing the pump not to pump oil. I hear no funny grinding noise from the pump. Planning to take my automotive stet scope to take a better listen.
2. Planning to check relief pressure setting at the flow control knob that regulates speed of fluid return from hydraulic cylinder. I can check to see if I have any pressure developed by pump.
3. Relief pressure setting can be adjusted, but see no evidence of any linkages coming loose and relief adjusting screw is perfectly protected by a cap.
4. if first two option proves futile then I reckon, I’m loosing fluid in to the rear end housing from seal rupture on the piston or by pass open on the spool valve attached to lift arm assembly.
5. I may have also need to take a look at the pump itself (last effort), pump is gear driven with a replacebale “seal kit” and no other serviceable parts. I cannot see that the gears all of the sudden are worn out to the point they can not pump. I‘m thinking, I might have pushed the seals on the pump to malfunction Rrupture) by keeping the 3 point hitch very high where it caused the vibration noise mentioned earlier. I was not able to find schematic of the pump to verify if it has a relief of some sort or not.

Well, I hope I did not make anyone fall asleep reading my stuff, appreciate if you can give me some pointer to augment my repair effort. Thanks a bunch.

Jetro

 

[jinman]

Okay, I'll make a wild stab...

When you raised the 3PH all the way up, the relief valve lifted because there is a misadjustment of the hydraulics that made it keep trying to lift when the 3PH was as high as the arms could go. That sound you heard was the relief valve.

The valve is probably clogged with residue of some sort and cannot completely reseat, thus your 3PH has very little or no power. If you raise the 3PH and shut off the engine, does the 3PH fall? Slowly? Fast?

Another possibility might be the seal on the 3PH lift cylinder. Perhaps it was not "used" to being extended so far (full height lift) under pressure and the seal started leaking (also making noise).

Too bad you don't have some way of checking system pressure like a remote hydraulic adapter where you could hook up a pressure gage. That would tell you whether the pump is working properly. If you talk to a dealer's service manager, they might know an easy way to identify if it's the pump or a leak in the 3PH system. Good luck!

 

[JC-jetro]

Okay, I'll make a wild stab...



Too bad you don't have some way of checking system pressure like a remote hydraulic adapter where you could hook up a pressure gage. That would tell you whether the pump is working properly. If you talk to a dealer's service manager, they might know an easy way to identify if it's the pump or a leak in the 3PH system. Good luck!

Thanks Jim for the advice. I'm actually going to do what you have suggested. I can check the relief pressure hence indication of pump operation at the Flow control valve knob as the pic indicates below. I also talked to dealer service manager, he was not tight lipped about it but was not in a advice giving mood either, was brief and mainly regurgitated what I just told him. I could hear the echo. He said $300 to haul the tractor to their shop and $75 an hour . I need to look for an oil filled pressure test kit good for 3000 psi. Also, I will not do it, but probably if I loosen the nut on the discharge pipe where it is attached to the pump and start the engine may give me indication of pump activity. If can prove pump operation then I'll start to look where I'm leaking oil. I sure hope when I take the suction screen off will see a clogged screen and that'll be the end of it.

Thanks again,

Jetro

 

[jinman]

Jet, that "position control rod" out of adjustment is exactly what I was referring to when you raised your 3PH all the way to the top. Mine was out of adjustment on my tractor and caused the relief valve to lift when I raised the lever all the way up. I readjusted it and it worked properly. If that could have happened on your tractor, your relief valve may have stuck open. If it did, you won't have nearly enough pressure during your test as shown in the illustrations.

That test is supposed to show where the system relieves pressure. If the valve is already in relief, it won't show you if your pump is okay. You'll only know one of about three things: the relief valve is stuck, you have a leak inside the reservoir, or the pump does not have pressure. You kinda already know it's one of these three things.

I would not hesitate to open the plumbing on the output side of the pump. I'd put a big 5-gal bucket under the pipe and then start the tractor. I suspect your maximum flow is 6 gpm or less and you can tell if the pump is putting out that kind of flow. Time it for 15 seconds and then measure the amount of fluid in the bucket. It won't tell you maximum pressure, but it should tell something about flow. If you do it right, you won't have that big a mess to clean up either.

 

[JC-jetro]

Jet, that "position control rod" out of adjustment is exactly what I was referring to when you raised your 3PH all the way to the top. Mine was out of adjustment on my tractor and caused the relief valve to lift when I raised the lever all the way up. I readjusted it and it worked properly.

I would not hesitate to open the plumbing on the output side of the pump. I'd put a big 5-gal bucket under the pipe and then start the tractor. I suspect your maximum flow is 6 gpm or less and you can tell if the pump is putting out that kind of flow. Time it for 15 seconds and then measure the amount of fluid in the bucket. It won't tell you maximum pressure, but it should tell something about flow. If you do it right, you won't have that big a mess to clean up either.

Thanks Jim,

Great Ideas, on the relief pressure setting, Correct me if I'm wrong, where you put your test gage shows amount of pressure that is exposed to relief chamber before fluid is expelled so you should be reading pressure even when you relive, spring tension can then be increased or decrease to change the relief setting to allow operation of your hydraulic lift. In other word even if you relive %100 of flow you'll still read pressure thus indicating of the pump flow. Please look at the pic below.

On Loosening up the plumbing, that is great idea, only I have quite a bit of respect for 2300 PSI. I reckon I can only loosen it just enough so it would leak out of the discharge, can wrap the discharge by some plastic , rubber (EPDM) so I can direct the flow in to a bucket by dripping rather than shooting oil all different directions. I particularly don't care how much I pump as long as I pump. I don't have FEL and once I get 3 point hitch up I'm content. I hope this coming Sunday I can get out there and try it.

Jetro



Thanks,

 

[jinman]

What I'm suggesting about the relief valve is that if you get a spike in pressure that drives it all the way open, the valve seat may hang in the open position with the spring unable to push it closed. By removing the valve and checking for cleanliness, you can eliminate that as a problem. If you have another emergency pressure relief valve, that could also be the issue and it may be down in the reservoir and not so easy to get to.

I think the most likely situation is that the main hydraulic cylinder for your lift has a blown seal.

To check flow out of the pump, you should completely loosen the connection so it is like a hose running into a bucket. With no or very little backpressure, there will not be 2300 psi of pressure. It will be like holding a garden hose over the bucket. As long as you don't try to stop the flow, it will probably be less than 50 psi. The flow should be brisk, but not a spewing mess. If you just "crack" the connection, you will be guaranteed to have a spewing mess at full pressure (much less flow but under tremendous pressure). That would be a dangerous situation. Think of how a spray bottle sprays an atomized mist under high pressure, but very little quantity. That will be what you'll have if you just barely open a connection.

If you spill fluid or it doesn't go where you want it, just shut off the tractor. It will stop flowing in a hurry.

Also, to check that your internal 3PH hydraulics are working properly, get the lift to go all the way up with the control handle in the up postion (if it will work at all). Then, shut off the tractor and watch to see if the lift drops. If it does, it's probably the internal lift cylinder. It will be time to pull the rockshaft assembly. If it's your hydraulic pump, the 3PH will stay in the up position.

So...to restate what you are looking for to isolate the problem:

If it is slow going up, but will stay up when the engine is shut off, it will be the pump or a leaking valve.

If the 3PH drops when the engine is shut off, then it's the internal cylinder or other leak in the 3PH assy.

 

[JC-jetro]

So...to restate what you are looking for to isolate the problem:

If it is slow going up, but will stay up when the engine is shut off, it will be the pump or a leaking valve.

If the 3PH drops when the engine is shut off, then it's the internal cylinder or other leak in the 3PH assy.

Thanks Jim,

excellent points. Will keep them in mind during my repair investigation.

Jetro

 

[JC-jetro]

So...to restate what you are looking for to isolate the problem:

If it is slow going up, but will stay up when the engine is shut off, it will be the pump or a leaking valve.

If the 3PH drops when the engine is shut off, then it's the internal cylinder or other leak in the 3PH assy.

Hi Jim,

I spent several hours yesterday and solved my problem.

Without changing any spring setting I disassembled the flow control assembly, I had a bit if the dirt in the check valve seat and that made no difference. The assembly functionally was the same as Shop manual but part were different.



I then without modifying the relief pressure setting I took the assembly off and inspected and cleaned it, all looked good and still no hydraulic pressure.

I then proceeded to change the hydraulic oil and clean the screen and this is what I found.

Screen with 25 year of operation without cleaning.



Cleaned screen.



There were no metal shaving in the " oat meal like" stuff in the rear end/differential but stuff were thick. I made a hook out of bailing wire and kept pulling the snot out. I then made a collection vacuum bottle and with a shop vac and a piece of garden house sucked up about 2 quarts of the stuff. any how, put everything together and gave her some new oil and she perked right up. My hydraulic issue is over. I bought parts to even change piston seal and all that but never had to go that far. I'm happy

Thanks for all of your input Jim
Jetro

 

[Doc_Bob]

Hi Jim,

I spent several hours yesterday and solved my problem.

Screen with 25 year of operation without cleaning.

Cleaned screen.

So you plan on doing it more often than every 25 years ?
Bob

 

[jinman]

Wow! That screen was a mess.

I went back to see your original post because I thought you had said you changed the filter, but I must have been confused. I guess this screen is the only filter your system has.

Perhaps loading the tractor on the trailer caused the muck to completely clog the last of the screen that had previously been open. Who knows?

I'm glad to see I was wrong about the lift cylinder seal being blown. I'm also sure you are glad that the pump wasn't DOA also.

I bet everything will work much better/quicker now.