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

[ScottB450]

Scott,

1- So the screen is cleaned I assume. Did you check it. if screen s dirty pump can cavitate. Need to make sure oil is available at the suction banjo connection.

I have not checked it myself. My dad handled this part. Can I, without losing all the fluid?

2- Have you changed the shaft seal on the pump? it is a double lip seal. On mine that was the culprit and it was sucking air.

Yes
3- There is the relief pressure device on the discharge side the pump on the right side of the lift cylinder housing? have you opened it with the pump on. That would show if you have flow.

I haven't tried this. I did run it, kill it and then crack the oulet off the pump. fluid leaks out. I will try it there.
4- Right at the housing there is a spring that sets your system pressure with a conical poppet valve, that would relife the pressure. if it is stuck at the open pressure it can relive the hyd fluid
directly in to the diffy.

I believe I had this off and wasn't sure what to look for. I pulled it apart and it looked ok. But if something was stuck, I wouldn't know it.

Thanks for your time!

Scott

Let me know,

JC,

PS. I had so many nice pics that they all got wiped from my picture hosting out fit. I do have them all but going back and put the right pics back in to the forum take tremendous amount of time. Ii can share the pics that yu might need.

 

[JC-jetro]

1- So the screen is cleaned I assume. Did you check it. if screen s dirty pump can cavitate. Need to make sure oil is available at the suction banjo connection.

I have not checked it myself. My dad handled this part. Can I, without losing all the fluid?
I suppose you can do it with minimal loss, by backing tractor on an incline (dangerous) or raise the rear up, securely on two tall jack stands to raise the diffy in reference to transmission to remove the banjo connection and withdrawing the inlet screen. I would personally dump the oil in a clean bucket or clean trash bag in a bucket. will be a bit messy. I will add a pic of before and after on a clean strainer. make sure to verify if your dad had don this work


2- Have you changed the shaft seal on the pump? it is a double lip seal. On mine that was the culprit and it was sucking air.

Yes
3- There is the relief pressure device on the discharge side the pump on the right side of the lift cylinder housing? have you opened it with the pump on. That would show if you have flow.

I haven't tried this. I did run it, kill it and then crack the oulet off the pump. fluid leaks out. I will try it there.
this thing is what regulate your discharge pressure by stiffness of the spring, some you would add shim , here you adjust the screw in and our to increase the stiffness, in case of over pressure or dead heading the pump then poppet will open up to protect the hyd pump, I will add some pics


4- Right at the housing there is a spring that sets your system pressure with a conical poppet valve, that would relief the pressure. if it is stuck at the open pressure it can relive the hyd fluid
directly in to the diffy.
please refer to pic on item 3, if you remove this and put a bucket under when you start the tractor it will dump oil without a whole lot of pressure to prove pump flow. puing against the spring gives your system pressure.
I believe I had this off and wasn't sure what to look for. I pulled it apart and it looked ok. But if something was stuck, I wouldn't know it.
soem genreal related pics of the area, ask if you have questions.



lastly inspect the ball and spring in the order I have in the pic below. that mechanism will remove the shock loading to lift piston on 3 point, if it is stuck open it can dump the oil in to diffy. This is a possibility but unlikely as the flow will still tray to raise the 3-point are while dumping passed the piston. if what you lift is really heavy it might not lift the load.




Let me know,

JC,

 

[ScottB450]

I pulled the return line from the pump, where the hard line with the banjo bolts to the area under the seat. I didn't start it, but just from cranking, oil came pouring out.
I removed the relief pressure apparatus. Took it apart. Didn't see any dirt lodged in there. I cleaned it out.


Let me ask this, if I happen to put the seal on the lift piston, backwards....would it still register pressure back there? I'm beginning to wonder if I messed this up.

Thanks!

 

[JC-jetro]

I pulled the return line from the pump, where the hard line with the banjo bolts to the area under the seat. I didn't start it, but just from cranking, oil came pouring out.

That is a good sign that you are pumping and have some flow
I removed the relief pressure apparatus. Took it apart. Didn't see any dirt lodged in there. I cleaned it out.

just remember you established flow. Spring now creates fluid pressure as pump pumping flow against the spring. I would not mess with adjustment yet, may be later.

Let me ask this, if I happen to put the seal on the lift piston, backwards....would it still register pressure back there? I'm beginning to wonder if I messed this up.

The seal is double lipped, same as what you had in your pump shaft seal but without the spring. The pressure and flow should face the lips to expand it against the cylinder wall. I think you will certainly have all flow blow by if the seal is put backward. unfortunately it is one time deal and old seal can not be taken out without damaging, just a suggestion. I left the seal in a plastic bag and in the sun while doing other work for it to soften a bit and then lubed it good and quickly install it without getting cold. I will add a few pics of my old seal.



JC,

 

[ScottB450]

I went back and checked my work. Looks like the seal is ok.
I'm not getting any oil to this part. The assemby grease is still on it and there is no hyd fluid.

Any ideas from this?

Thanks

 

[JC-jetro]

I went back and checked my work. Looks like the seal is ok.
I'm not getting any oil to this part. The assemby grease is still on it and there is no hyd fluid.

Any ideas from this?

Thanks



View attachment 619654

View attachment 619655

View attachment 619656

It will be a messy, but why don't you take the banjo connection on the discharge of the pump lose, it is a shorter dia pipe. put a bucket under it and start the tractor. see if you can get any flow passed the pump bypassing all the hyd controls. If you get flow that's good. If you don't , whether the pump is bad or suction screen is still plugged. I have a few pics below to help. In my case, I made a collection jar and used a shop vac to suck up the gunk in the bottom of the diffy housing floor and I was able to suck up more than couple of lbs of sedimentation, all soft and gooey oil and contaminants. if that is not cleaned , it can still plug up the screen fast. The pump suction needs to be flooded with oil to prime the pump.

JC,






P.S Added , one extra picture here, look at the hole I put on the handle of collection jar. The purpose is not to collapse the jar bu suction/vacuum/. when I need suction , i pout my thumb on the hole to suck contaminant/oil and let go just before the can collapses. Of course, if your collection jar is a metal bucket container you would not need the hole.

 

[ScottB450]

I pulled the line directly off the outlet of the pump. Started it and it has good flow!




Thanks!

 

[JC-jetro]

I pulled the line directly off the outlet of the pump. Started it and it has good flow!




Thanks!

Ok, that's good. Now take the relief pressure valve completely off. That includes the conical poppet , spring and the holder. put a bucket under and run the tractor to verify if you have flowup to the relief valve.


If you have flow, then you have to establish if your lift spool valve is working properly by either removing the bolt on the cylinder head to establish flow or pressure. It would begreat if you had an oil filled pressure gauge up to 3000 psi like what I have shown on the picture below.




On picture below, the opening with plug removed can be used as oil return line in to diffy. You would need to remove the top plug or where I had my oil pressure gauge there in the previous picture.


what you see in the pics below is your lift piston spool valve. picture is from outside and then inside on differential cover. That valve either divert flow to the lift piston or return to diffy housing. you might have flow right to the spool but all might be diverted. Test above would verify it.


report back with your findings.

JC,

 

[ScottB450]

I have a pressure gauge. Has read zero through all this.




I pulled the valve off and oil came shooting out of the hole I'm pointing to.



So, I'm guessing this leads to the spool valve?

Thanks for the help!
Scott

 

[JC-jetro]

I have a pressure gauge. Has read zero through all this.

View attachment 620142


I pulled the valve off and oil came shooting out of the hole I'm pointing to.

View attachment 620141

So, I'm guessing this leads to the spool valve?

Thanks for the help!
Scott

Scott,

Please look at the pressure relief device picture, my suggestion was to remove the spring,poppet and the holder, then watch if you get flow coming out. we needed to inspect the spring and the popet also. the flow might be going back to diffy before even going to spool. did you read zero pressure after you pit it together. I also suggested to remove the plug right at the cyllinder head to see you get flow there. have yu done that?

JC