2020 hydraulic problem

[BillFinn]

I am working on a 2020 for a friend. He installed a rebuilt main pump off the crankshaft. It is making a rythmic harmonic noise from the pump. While diagnosing I realize the charge pump is sending to the cooler than the resovoir than to the pump. I know it should work supplying oil in reverse to the pump. Has anyone experienced this and would have a solution. The lines both run parallel to the rear under the floor pan. Should they cross somewhere.

 

[Jim.ME]

The JD 2020 service manual (publication # SM2072) has flow diagrams. He should invest in one if he does have one.

Does it have open center power steering or closed center power steering? Need to know that to scan the right info for you. Closed center will have a small tubing line going up to the steering column on the pump side of the pressure control valve.

 

[BillFinn]

The pump is closed center

 

[Harry in Ky]

How do you know the charge pump is supplying oil to the cooler? Yes, that's backwards. The charge pump line (solid steel line) goes to the port in the clutch housing nearest the brake valve. Excess flow from the pump goes to the reservoir and the cooler. Those lines can be reversed easily enough (even though it doesn't look like it) and if so the hydraulics won't work. So currently what works and what doesn't? Is it just a noise that's concerning?

 

[Jim.ME]

The pump is closed center

Yes, the main pump is closed center. However, the steering could have a separate open center pump drawing off supply oil going to the main pump or it could use the pressurized oil from the main pump. If it has open center power steering there will be a small pump almost hidden in behind the alternator.

Were those main lines removed for a reason? If the lines were removed, is the check valve assembly in the clutch housing end of the line supplying the pump? As Harry posted it would be the one nearest the brake valve.

 

[BillFinn]

I ran the line between the cooler and resovoir to a bucket and oil came from the cooler side. We have poor steering and chattering loader functions. I realize the flow is wrong, but it should still charge the main pump. Does anyone know of a reason backwards would not work.

 

[BillFinn]

Steering pulls from a tee in the high pressure line from main pump located. Just ahead of lh foot pan

 

[Tx Jim]

Was any hyd diagnostic procedures performed before front pump was replaced? Is this 2020 serial # below or above 045,199 which is the serial break between open center & closed center power steering?????????????

 

[BillFinn]

Lines were removed for a clutch replacement.

 

[BillFinn]

Owner thought front pump made noise so installed a rebuilt. No diagnosis was performed before that replacement. I have determined that the transmission pump supplies a lot of oil at idle with no cooler hose on it. I suspect a sticking load control on the pump. I will check psi at remote couplers to see if it is steady and accurate.

 

[Harry in Ky]

Lines removed for clutch replacement? Which line is which now at the clutch housing? That's probably why the flow is reversed.

 

[Jim.ME]

Steering pulls from a tee in the high pressure line from main pump located. Just ahead of lh foot pan

I think you mean the right-side foot pan. If the pressure line has a tap similar to the one in the picture, it would be closed center steering.

 

[BillFinn]

Yes your correct rh side just like the picture. I feel the only way possible for the flow to be reversed was for the lines to get crossed at reassembly. I am more interested to know if that could cause any symptoms.

 

[Jim.ME]

Yes your correct rh side just like the picture. I feel the only way possible for the flow to be reversed was for the lines to get crossed at reassembly. I am more interested to know if that could cause any symptoms.

I will say it could cause symptoms if the main pump was not being supplied oil correctly and if the supply line check valve is in place the oil can't go through it which would need to happen as you are describing the flow. You need to determine if the lines are in the wrong places and if the check valve is in the line supplying the main pump and correct them if needed. They need to be in the right locations as a starting point.

 

[Harry in Ky]

I don't think you understand what I'm pointing out. The lines that you probably have crossed are the two under the engine that fit into two holes in the front of the clutch housing. The ones with the metal tab held in by a single 3/8 bolt. The steering and high pressure lines have nothing to do with your problem.

Again, the charge line is solid steel and goes to the pump. It fits in the port nearest the brake valve. The return line comes from the bottom of the cooler and fits in the port towards the centerline of the tractor.

 

[Jim.ME]

And the charge line also has a check valve that can fall apart and get lost when the line is removed from the port in the clutch housing, if one doesn't know about it.

 

[BillFinn]

Perfect info, that's the base I need to cover. I will be back on the jod next week. Thankyou all for your help. I will post my findings next week.