Aaargh! 3-pt hitch not lifting any weight.

[J_J]

With a 1000 lb load on the 3pt, can you tell me what pressure you read with the 3pt lever up, but not at the relief pressure?

It will take a very large load to test the safety valve.

If you get high pressure, using the 3pt lever, that means that the cyl has fluid and is at the end of the stroke, and if the load is not lifting, the relief should go off.

Seems like a while ago, someone had trouble with their 3pt, and the 3pt cyl was coming out of the cyl bore to far and the fluid was just flowing past the cyl seals into the sump.

 

[The Haymaker]

I just posted this on my thread for my Dads 955 with a similar, and sudden onset, issue. Very simple fix on his part, but the troubleshooting process was painful. Had you noticed any frothy oil when this started?



So, my dad has run the gamut on this rig, I think he may have lost a little hair over this one. He rebuilt the piston and noticed a SLIGHT improvement. He took a chance and honed the cylinder. There was an improvement, but it did not cure the problem. It did stop the settling of the hitch that has been going on for a few years.

He cleaned the pressure valves and replaced every o-ring he came to in that section of the tractor. He inspected the 3pt control valve. Nothing.

He had the local Deere shop stumped. Their last recommendation was toasted seals on the charge pump.

So, he just replaced a 35.00 chunk of hose on the return from his added spool valves, which is not a new addition. At the same time, he also found that the filter was loose, though not leaking. He had changed it last about a month ago, just prior to this issue, without removing the MMM.

PROBLEM SOLVED. Either the filter or hose was sucking air. The filter leaked no oil until yesterday and the line just stayed wet.

Back when this started, he thought the oil looked frothy. I asked him where he was sucking air and he said there was no place it could happen.

The old man is pretty happy right now, despite wasting a LOT of labor when he could have been finishing roadsides or starting the fall tilling, he had a relatively cheap fix!

 

[project_X]

I just posted this on my thread for my Dads 955 with a similar, and sudden onset, issue. Very simple fix on his part, but the troubleshooting process was painful. Had you noticed any frothy oil when this started?



So, my dad has run the gamut on this rig, I think he may have lost a little hair over this one. He rebuilt the piston and noticed a SLIGHT improvement. He took a chance and honed the cylinder. There was an improvement, but it did not cure the problem. It did stop the settling of the hitch that has been going on for a few years.

He cleaned the pressure valves and replaced every o-ring he came to in that section of the tractor. He inspected the 3pt control valve. Nothing.

He had the local Deere shop stumped. Their last recommendation was toasted seals on the charge pump.

So, he just replaced a 35.00 chunk of hose on the return from his added spool valves, which is not a new addition. At the same time, he also found that the filter was loose, though not leaking. He had changed it last about a month ago, just prior to this issue, without removing the MMM.

PROBLEM SOLVED. Either the filter or hose was sucking air. The filter leaked no oil until yesterday and the line just stayed wet.

Back when this started, he thought the oil looked frothy. I asked him where he was sucking air and he said there was no place it could happen.

The old man is pretty happy right now, despite wasting a LOT of labor when he could have been finishing roadsides or starting the fall tilling, he had a relatively cheap fix!

I just read your response in your original thread (I was watching it intently) and as soon as I free up some time I'm going to check my filter too. I had just change my filter before this happened too....
Was his loader working? Mine works fine.

 

[The Haymaker]

It was working, but he didn't feel it had the "oomph" it should have, but it was a subtle, if any, change. This did start immediately after the change.

I'd start going after any oil leak you can find, but then, where it was suction, neither of this leaks he fixed gave much of a hint.

His pressure ran 500lbs low, but I don't think he has checked it since the fix.

 

[project_X]

i checked the spin on filter and it was tight. my problems started before i changed the oil, so it is likely not the filter. tomorrow, i will look at the suction line very carefully. i hope i find a leak, because i am out of ideas....

 

[project_X]

Today, I isolated the relief valve. I installed the by-pass plug and attached a gauge to the out port, this effectively dead heads the pump forcing the relief valve to open. It opened at 2100psi or so. So relief valve is confirmed good.

Recap:
Relief Valve is good
Lift Cylinder is good
Filters/Fluid good
Checked for leaks and suction line, all seem ok
Pump is good (flow >3gpm. pressure >2200psi)
Loader and Remotes work as expected.
Seals in control valve all changed.

 

[J_J]

Are you saying that the 3pt still will not raise?

When you lift the 3pt lever, is anything happening, and if not, that means that the 3pt valve is not directing fluid anywhere except to tank.

Can you get fluid into the 3pt cyl?

If the 3pt is relieving, the 3pt cyl is at it's limit. If the 3pt is raised and you close off the lock valve, and you put some weight on the 3pt. does the cyl hold ?

If the cyl will hold weight, that means that the 3pt lever has sent fluid into the 3pt cyl.

You may have some mechanical defects.

 

[project_X]

The 3pt hitch raises, but won't lift any weight.
The 3pt hitch holds as much weight as I can put on it.
Fluid is getting to the cylinder.

I found the problem!!
Today, I took the cylinder and valve assembly off the tractor and put air in the HP IN line to hear where the air was leaking.

It appears that the flow control portion of the valve is no moving as it should. I'm not able to get it out yet to verify, but it appears to be sticking.

It is parts 9,8,24 and 10 which I can't seem to be able to remove.

 

[Leejohn]

I still think you are back on track with the valve. I have no ideal how that plug comes out. Every time you post I think, boy he has found it.

 

[project_X]

I still think you are back on track with the valve. I have no ideal how that plug comes out. Every time you post I think, boy he has found it.

I have some confidence in this, the air I put through the valve was coming straight out the bottom of the valve, however by exercising the flow control valve with a punch (compressing the spring and letting it come back) varies the amount of air out the bottom to the "sump".

If I can ever get it apart,....