Aux hydraulics and 3pt lift

[slb04786]

Hey guys,

Phase two of my hydraulics and HST issues. I was able to get everything going in my original thread by replacing the hydraulic pump and associated internal gear. You can read up on that at this link: Loss of Hydraulics and HST. Everything is working with the exception of the 3pt lift arms and hydraulics to my backhoe. I know from experience that the two are related. If you move the 3pt lever off neutral while using backhoe you lose your hydraulics to the backhoe. The pressure port is fed off a manifold that is bolted to the Main Hydraulics Valve that sits on top of the hydraulic pump under the floor pan beneath your left leg. I have taken the pressure hose off that goes to the backhoe, put it in a 5 gal bucket and started the tractor and operated the 3pt lever. Didn't get a drop from it. the other metal tube on that manifold goes to the pressure port on the loader control valve. The loader works fine. Looking at the service manual it appears these two metal tubes have different flow rates controlled by the flow divider inside the main hydraulics control valve. Here is my dilemma, researching the no lift issue I have seen a couple of post about the lift piston rusting and sticking in the top of the transmission.
so I am torn between tearing into the main hydraulics control valve or tearing the seat, fuel, tank, transmission, and linkage apart to check the 3pt piston. The 3pt piston would be a bigger job but the main control valve is NLA so if I tear into it and boogger it up I in a jam. Do any of you have experience working on this valve. I am inclined to think it is in the valve because I have a hard time believing that the stuck piston would kill the pressure line. Thoughts?

 

[oldnslo]

You are correct that no oil coming out of the supply is a separate problem from rusted or leaking lift cylinder.

Something in main flow divider valve could potentially prevent flow from going to the 3 point.

Do you have a parts break down for this valve?

 

[slb04786]

You are correct that no oil coming out of the supply is a separate problem from rusted or leaking lift cylinder.

Something in main flow divider valve could potentially prevent flow from going to the 3 point.

Do you have a parts break down for this valve?

Yes, I have the breakdown from the service book as well as the parts book. It has been 1 step forward and 2 steps back with this tractor. I have owned it since 2015 and have worked it hard with no issues. In 2022 we retired and sold our home in Maine to move to Florida. I gave the TLB tractor, mm mower, and 3pt snowblower to my son as he just has a garden tractor with a snowblower and mower deck. I told him to keep it parked inside or under a tarp when not using it. Every time I have gone there since it is outside and not covered. When I mention it he says "Those tractors are made to sit outside" I protest but what do I know. So fast forward to this spring and I return to Maine for the summer. I get a call, "The tractor isn't working". No hydraulics or power steering. The tractor would still move, the 4wd was locked in. Turns out the transmission is full of water and hydraulic fluid and the hydraulic pump spline shaft is toast. Got that all fixed the other day, went over today to work on the hydraulics for the bh and the loader valve stopped working and started pissing fluid out around the spool. I told him when I get this fixed it has to stay inside. I can't go through this again. Thanks for letting me vent. I have some o-rings ordered. I have the loader and the main control valves off the tractor but haven't torn into them yet. I think I will start with the flow divider first.

 

[oldnslo]

If system was full of water there is a chance crud is still in the system and possibly plugged an orifice or is causing a spool to bind.

 

[DMW]

Is the valve for the mower deck height adjustment open? If it is fully closed, it will stop flow to the 3pt. Below the seat, between your legs.

 

[slb04786]

Is the valve for the mower deck height adjustment open? If it is fully closed, it will stop flow to the 3pt. Below the seat, between your legs.

That is the main control valve that I refer to. It has a flow divider in it that divides the GPM coming out of the pump into 4GPM to the loader and 2GPM to the aux port which is the backhoe. And you are correct it also controls the 3pt lift and does shut hydraulics down to the aux port when the 3pt lever isn't in neutral position. I have taken it off the tractor and will be doing an autopsy, hopefully today, and would like to determine the exact cause and not just put o-rings in and hope for the best. I will be looking at the flow divider and the 3pt spool closely. Thanks for the response, stay tuned. I will post my results or observations as there isn't many post on here about this part/circuit and I want others to be helped just like I have been. Plus my memory isn't the best anymore!

 

[slb04786]

If system was full of water there is a chance crud is still in the system and possibly plugged an orifice or is causing a spool to bind.

I think you are correct. When this happened the loader raise/lower spool stuck and the pressure relief would activate when I tried to roll the bucket or raise/lower the bucket. Hoping to get into it today. I don't think I want to take the pressure relief apart as I think that is the part have read other post saying it is full of parts and you will never get it back together if it falls apart. We will see. I will keep you all posted.

 

[dicktill]

That is the main control valve that I refer to. It has a flow divider in it that divides the GPM coming out of the pump into 4GPM to the loader and 2GPM to the aux port which is the backhoe. And you are correct it also controls the 3pt lift and does shut hydraulics down to the aux port when the 3pt lever isn't in neutral position. I have taken it off the tractor and will be doing an autopsy, hopefully today, and would like to determine the exact cause and not just put o-rings in and hope for the best. I will be looking at the flow divider and the 3pt spool closely. Thanks for the response, stay tuned. I will post my results or observations as there isn't many post on here about this part/circuit and I want others to be helped just like I have been. Plus my memory isn't the best anymore!

Are you sure about that? Do you have a hydraulic diagram for it?

The reason I ask is because on my 2022 GC 1723EB the flow divider divides flow between the steering and "everything else". The "everything else" is the loader valve, then the backhoe, and then the 3-point, all via power beyond.

The control valve is "strange" in that it has two sections within it, the flow divider and the 3-point valve. As best I can tell, they are essentially two separate units with no interconnection except for a common tank return.

See my posting: How Massey Ferguson GC 1723 & 1725 hydraulics are plumbed

 

[DMW]

That is the main control valve that I refer to. It has a flow divider in it that divides the GPM coming out of the pump into 4GPM to the loader and 2GPM to the aux port which is the backhoe. And you are correct it also controls the 3pt lift and does shut hydraulics down to the aux port when the 3pt lever isn't in neutral position. I have taken it off the tractor and will be doing an autopsy, hopefully today, and would like to determine the exact cause and not just put o-rings in and hope for the best. I will be looking at the flow divider and the 3pt spool closely. Thanks for the response, stay tuned. I will post my results or observations as there isn't many post on here about this part/circuit and I want others to be helped just like I have been. Plus my memory isn't the best anymore!

Just to clarify, There is no flow going to the 3pt when the raise function is selected. Is the shaft turning freely ?

 

[slb04786]

Are you sure about that? Do you have a hydraulic diagram for it?

The reason I ask is because on my 2022 GC 1723EB the flow divider divides flow between the steering and "everything else". The "everything else" is the loader valve, then the backhoe, and then the 3-point, all via power beyond.

The control valve is "strange" in that it has two sections within it, the flow divider and the 3-point valve. As best I can tell, they are essentially two separate units with no interconnection except for a common tank return.

See my posting: How Massey Ferguson GC 1723 & 1725 hydraulics are plumbed

You are correct. I tore into the main control valve and found that what I thought was the pressure line for the backhoe was actually the return line which it shares with the 3pt valve. I will check your post on the 1723 plumbing. I would expect them to be similar. Thank you for replying and setting me straight.
Stan