3 ponit hitch will not operate

[tmoto]

I bought a 2007 Mahindra 2015 at an auction. It has a Mahindra loader that works fine but the 3pt hitch will not operate. The lift lever for the 3 pt was rusted so bad it would not move. I lubed it and still nothing. The loader and 3 pt. share the same pump. I took the head off of the lift cylinder and the piston was slightly stuck in the bore but no rust. I decided to take the entire hydraulic cylinder nd manifold off. The valve body was not operating correctly with air pressure so I took it all apart, cleaned and lubed everything and put it back together. It would then bench test properly with air pressure. I put it all back on the tractor and still nothing. I then took the diverter valve apart and cleaned it. No problems were found but I deciced to shim the relief valve some to up the pressure to the rear. Still nothing. I took the lift cylinder head back off and it does flow fluid through the passage but not at idle and only at about 10 psi at rated rpm. The only thing I can come up with is a weak pump. The tractor has 650 hours. I do not mind to put a pump on it but I do not understand how the loader has great lifting ability at idle and rpm so how can the 3 pt lift not work? I also put air pressure to the hydraulic line going to the 3 point at the distribution block and the lift and lower lever as well at the 3 point operated so it has to be a pressure problem.

 

[carmedic310]

had that happen on a mahindra I had .Turned out to be the knob under the front of the seat.kids were playing around the tractor and must have turned it

 

[tmoto]

I checked that also. It is not that, Screwed all the way in it does hit a relief valve but it is not the problem. Thanks

 

[Leejohn]

Check the loader valve and make sure it has the PB fitting in place.

 

[J_J]

Remove the hose going to the 3pt and see if there is pump flow.

If the PB adapter was not installed, and the PB port is plugged, the output from the loader flow path is to tank.

If your loader has a PB port, then install the PB adapter and run the PB adapter port to the 3pt.

The loader OUT should only go to tank.

 

[tmoto]

there are 3 lines going to my loader joystick control from the distribution block. 2 going into the face beside the lines going to the loader cylinders, one on either side. The 3rd line is connected to the side of the joystick control. I assume the 2 going in the face are pressure in and out and the one on the side is return? The one from the side of the joystick is connected to the distribution block marked "N" which is beside the 3 point hitch line. The 2 that go into the face of the joystick are connected to the block ports marked "P" which is nearest the hydraulic input from the pump, and "T" which is on the top side of the block nearest the return line. Are the lines on the wrong ports? I'm not sure about a PB insert and really do not know much about the power beyond. Thanks for your help

 

[J_J]

Can you show a pic of the 7 lines going into the loader valve.

Can you ID the ports on the loader valve?

Is one of the ports marked PBY or CO or PB?

P = pump in flow or pressure in.

T = tank flow

 

[tmoto]

after searching the internet, I found that the loader is hooked up properly. The P is the pressure port, The T is return to the tank and n is power beyond. I have a pressure gage coming tomorrow to check the actual pressure. With the N hose disconnected there is not a lot of pressure coming out. There is also a loader bypass switch on my block that bypasses the loader. With it switched to just 3 point, my hitch will still not raise. How much pressure should I have at the PB port?

 

[J_J]

You will only have pressure when a cyl or motor is doing work.

In an open center hyd system, with all valves in neutral, the pump just pushes fluid through all valves at very little pressure.

If you operate the 3pt lever you cause the fluid to go to the 3pt cyl, and build pressure.

Remove the hose at the 3pt and activate the 3pt lever and see if you have pump flow. Use bucket to collect fluid.

 

[tmoto]

I have done that. There is flow but not much pressure. I worked the 3pt with the head off of the lift cylinder and when I lift the lift lever fluid comes out of the fluid hole but does not blast all over. It is about a 5/16 hole. It flows out in a stream about 6" before it starts to drop. Not much pressure.

 

[tmoto]

My pressure gauge is not here yet but after I manually lifted the 3 pt arms up I noticed they would stay up. The lift piston is getting fluid apparently so I let it down and cycled this a few times. Now at rated rpm the 3t goes up and down but not on an idle and it will not lift my weight. I was messing around and IF I LET THE LOADER DOWN THE 3 PT GOES UP FAST AND HAS POWER, but if I leave the loader in a set position the tractor must be revved up and the 3 pt has no lifting power. This thing is killing me!

 

[J_J]

This statement tells me that the 3pt is only getting fluid when you use the loader, 3pt is using loader cyl expended fluid. Not correct.

[ I was messing around and IF I LET THE LOADER DOWN THE 3 PT GOES UP FAST AND HAS POWER]


I am thinking you have hoses switched.

The N hose from the loader valve should feed the distribution blk and then to the 3pt.

With your loader is neutral, pump flow should pass through the loader valve and go to the 3pt.

Cut engine off and with the loader in neutral, remove the tank hose start engine and see if any fluid is flowing from the tank hose. If it is, you be in trouble.

With the loader in neutral, there should be no fluid in the tank line.

 

[tmoto]

I tried it and nothing comes out of the tank hose when the tractor is running. I tried switching the T and P hoses. The loader had no pressure and the 3 point worked weak like it has been.

 

[tmoto]

 

[tmoto]

 

[J_J]

If you have pump flow at the 3pt, tee in a hyd pressure gage and operate the 3pt lever. Should see relief pressure

If no or very little pressure, then the 3pt cyl seals are bad or there is a hole in the piston.

You should have full pump flow at the 3pt with the loader valve in neutral. . If not, then the system is not plumbed correctly.

Check pressure on the loader. It should be the same at the 3pt if all components are good.

 

[tmoto]

that is definitely not the problem. Once up it will stay up for days and once up it will hold lots of weight. it will not lift weight but once up it will hold anything.

 

[Leejohn]

In post 15 picture why do you have a B and Y on the fittings? They look like work ports to me. What hose in that picture do you have for in and where is the other end going to?

 

[J_J]

You still have not answered the questions that I asked.

Do you have full pump flow at the 3pt input?

If your 3pt will hold weight, then the seals are good.

If the 3pt only works when you use the loader, then something is plumbed wrong.

Do you have a hose from the hyd blk going back to the 3pt? I believe the N hose on the hyd blk is from the loader PBY if you have that port.

 

[tmoto]

FACTS
1. There is flow to the 3pt. hitch, flow at idle, more flow at RPM.
2. PBY port is plumbed to the N port.
3. 3pt. works slow and not powerful anytime at rated RPM, no movement at idle, but has flow back to it at idle.
4. 3pt. does not leak down and holds weight for 48 hours so far in any up position.
5. 3pt. seems to work more normally WHILE I let the loader down from the up position, loader otherwise makes no difference.
6. There is only a steel line from block going back to 3pt.
7. There is a loader shutoff valve on block that I have shut off so only 3pt. gets hydraulic fluid. 3pt. operates exactly the same with load shut off or on. Weak and slow.
8. Loader has power and very responsive at idle and RPM and runs off of the same pump as 3pt.
9. I have blown air through the pressure line that feeds the 3pt. , no obstructions.
10. I have blown air through the return line from 3pt., no obstructions
11. There is no screen on pump inlet at fluid housing or fluid pickup by design so good fluid pickup.
12. Changed the hydraulic fluid and spin on filter with PROPER fluid, fluid level, and no change in performance.
13. Loader and 3pt. are getting the same FEED/BASELINE pressure.
14. Loader turns feed pressure into a little over 2000 psi.
15. I have shimmed relief valve in block to up pressure but makes no operational difference
16. I shimmed a relief valve on 3pt. cylinder head to up pressure and no operational difference
17. 3pt. control valve body operates fine on air pressure with no air leaks on sliding pistons etc. on test bench
18. 3pt was non operational at purchase and had not been used in a long time, fluid and filter appeared very clean prior to fluid/filter change but had same operating problems before and after fluid change.

QUESTION
What turns fluid flow to the rear 3pt. into high pressure or does it just up itself going through the smaller passages?

Comments
Facts make no cense to me, it seems like a fluid flow problem or a relief valve problem only at 3pt. hitch. When I let the loader down, I think the 3pt. operates faster because the fluid flow of the loader cylinders emptying seems to raise the common pressure in the block by 10 psi as the fluid flows back to the tank. Thank You for sticking with me on this.