JD 2550 pump question

[Tx Jim]

One needs to test each hyd component for pressure,flow(GPM) & temperature. Many closed center hyd pumps have been replaced to learn that frt pump was fine and some other hyd component was at fault. One simple test is look in hyd filler hole for spraying oil with 3 pt raised while engine is running.

 

[wdchyd]

As above have stated, you need a flow/load meter test......everything else will just be guessing

Pumps that pump so/so when cold or at high revs but get worse when it warms or idle is classic symptom of pump worn out.....rule out the pump first

 

[Tx Jim]

As above have stated, you need a flow/load meter test......everything else will just be guessing

Pumps that pump so/so when cold or at high revs but get worse when it warms or idle is classic symptom of pump worn out.....rule out the pump first

I disagree since frt pump can't suck oil it is very dependent on oil being supplied from trans pump. Also major internal high pressure leak will rob a good pump of it's output. One needs to eliminate internal leaks,check trans pump flow before condemning frt pump. Many JD frt pumps have been replaced with new pumps to determine that pump wasn't the problem. Closed center hyd's problems can be a PITA to diagnose.

 

[J_J]

All gear pumps can suck oil from a tank.

However if the supply is too low or is reduced such as a transmission fed pump, then it will make lots of noise and eventually wear out if not corrected.

You can also remove the pump for a flow and pressure test.

On a closed center system, you can check the out/tank line for flow when there should be none with all valves in neutral.

 

[Tx Jim]

All gear pumps can suck oil from a tank.

JD frt pump on closed center system is a piston pump. Removing JD frt pump is a job that one will not want to accomplish very often.

 

[MMagis]

On a closed center system, you can check the out/tank line for flow when there should be none with all valves in neutral.

Are you saying to check each valve for flow separately, or check the main pump? I was thinking there would always be flow from the main pump since components such as steering and trans pump use the same fluid.

So my next step is to check the trans pump and main pump for flow/pressure? I apologize if this is a dumb question, but is there a way to supply fluid to the front pump externally to guarantee its getting fluid?

 

[J_J]

To check each valve for leakage, remove the OUT hose.

I an not sure if the closed center pump uses a separate return line for excess flow or returns the flow back to the IN port of the pump. .

 

[Tx Jim]

To check each valve for leakage, remove the OUT hose.

I an not sure if the closed center pump uses a separate return line for excess flow or returns the flow back to the IN port of the pump. .

I think power steering valve has no return hose to check flow. Actually frt pump isn't designed to have excess flow because when stand-by pressure is attained hyd pump stops pumping oil.

 

[wdchyd]

I disagree since frt pump can't suck oil it is very dependent on oil being supplied from trans pump. Also major internal high pressure leak will rob a good pump of it's output. One needs to eliminate internal leaks,check trans pump flow before condemning frt pump. Many JD frt pumps have been replaced with new pumps to determine that pump wasn't the problem. Closed center hyd's problems can be a PITA to diagnose.

Oops, my bad........was thinking it was a positive displ open center pump:ashamed:

 

[DLHWoodstock]

Hey Guys
I am here searching because I am in the same boat as MMagis was. I hope he found and fixed his problem. I am in North Carolina this weekend and after two days of hard work my 1985 JD 2550 loader and three point quite working. Friday I did have a chattering in the hydraulics a few time but it quit and things worked properly when it went away. Yesterday it was working great and I got off and back on and now I can barely get the buck or the three point up. By barely i mean a my not be able to load the tractor up on the trailer. The steering works normal and I was told that comes from the internal pump, is that correct?. I do not have my pressure gauge or many tools, as they’re back in Georgia so i am handicapped at this point. Please give me your thoughts and opinion. I will check what I can before taking it somewhere. I will try to raise the three point after church and see if I can see any oil leaking internally. Thank you in advance

 

[Tx Jim]

If power steering operates correctly it's possible stand-by pressure which should be 2250psi has lowered to 1700 psi. This lower psi allows pressure control valve(item 15) to block pressure to 3pt hitch, scv & fel control valve. It's also possible stroke control valve isn't seating as designed due to foreign material in seating area. If your tractor hyd pump has a de-stroking screw(item 6) one can with engine operating at idle speed turn de-stroking screw CCW to open stroke control valve then turn DS screw CW & if you're lucky foreign material if present will be dislodged from SC valve seating area. You could if de-stroking SC valve doesn't solve pressure problem possibly attempt to back your tractor on trailer dragging bucket rearward.

 

[DLHWoodstock]

Hey Guys
I just wanted everyone to know that the problem with my 2550 tractor and 245 FEL has been corrected. Tx Jim was a great help to me and gave me the information i needed to fix it. It appears that the stroke control seat had some debris in it, not allowing it to seat properly.

I did check for internal leak the best I could and did not see anything. Second I installed my pressure gauge in the right rear remote. Pressure was bouncing between 500 and 600 PSI. After a lot of instruction from Jim I backed off the de-stroke (item 6 in Jim’s screen shot or Item 43 in the diagram of a 40 CM3 pump) about three or four turns. Then with engine idling for about 2 to 3 minutes I slowly turned the de-stroke back in. At some point I noticed the pitch of the pump changed, and the pressure started climbing. At that point I had 800 psi and stable. I slowly continued to return the de-stroke into its original place and my pressures came up to 2350 psi. At that point I went under the tractor and backed off the stroke control valve to return the pressure to 2250 psi. From looking at the manual I believe this was the correct pressure setting. With the tractor at full throttle, the pressure was about 2325 psi.

Thanks to Jim first and to all of you who replied. I was able to get my tractor up and running and I truly appreciate all of your input. I hope this helps someone else in the future.

God Bless

 

[DLHWoodstock]

HYDRAULIC PUMP MODEL NO. 34PP1 40 CM3 (2.4 IN3) - ST230612​