Weak hydraulics- bad pump or relief valve

I have isolated my backhoe (723) and gone through the controls for the controls for the loader with a flow meter and my pump makes good pressure until the psi is increased. At idle with no load, my pump will be in 10-13 gpm range. At 1600 rpm its over 20, but as soon as the psi hit around 1200, the flow dropped to under 5. There is not really an easy way to isolate the pump, I cant get a connection off the pump or the connection to the controls without taking off every line.

The relief valve would be the easiest to fix, but I cant seem to find one. The control I have is the Cessna one. I wouldnt mind changing that out if I could find one and also if that was thought to be the issue. If it is the front pump, I believe I can still find a replacement for that, from this site.

1964 4000 gas front pump.
mvphoto92378.jpg


mvphoto92379.jpg
 
I don't think you need to isolate the pump
for troubleshooting. You have two system
relief valves, one in the 712 loader valve
and one in the 723 backhoe valve. Do you
hear either of the reliefs unseating when
you reach max pressure (usually a squeal)?
You should be able to reach around 2000
psi if you operate one of the backhoe
cylinders against the stop, for example
pull the boom (or dipper) up all the way
and hold. If you can't reach full
pressure and relief is not popping
probably weak pump, suction restriction,
or low fluid level. I guess you could
also have fluid bypass under pressure.
 
<img SRC=https://i.postimg.cc/C177Dv1T/Ford713-Troubleshoot-P1.jpg>

<img SRC=https://i.postimg.cc/yxrTpkcL/Ford713-Troubleshoot-P2.jpg>
 
I thought about this too ... first stop after the pump is the 712 loader valve. If you gauge at this point, curl the bucket against the stop and hold can you reach relief pressure of around 2000 PSI and hear the relief unseat?
 
(quoted from post at 14:00:36 05/21/22) I thought about this too ... first stop after the pump is the 712 loader valve. If you gauge at this point, curl the bucket against the stop and hold can you reach relief pressure of around 2000 PSI and hear the relief unseat?

Thats so much info and its great thank you!

So I guess from the beginning- I bought the tractor not running and got it running and ruining well. I used the front loader to move some small amounts of dirt, and nothing really heavy. I tried the backhoe and it wouldnt dig. It could barely get the teeth to cut in. So I went to the backhoe relief and it was almost all the way screwed down. So I put a pressure gauge on the dipper cylinder and could build 1400 psi.

I then disconnected the feed out of the loader control for the backhoe and return off the filter housing for the backhoe to remove that from the system, and add in my otc tester.

My tester measured the flow and psi above hooked up that way.

When I think back, Im pretty sure if I pulled the backhoe up it would bog the engine a bit and Id hear the relief. The front end loader could not lift the front off the ground more than a few inches either and I think I heard that squeal too. Is there a part number for the relief to replace it with? I do not seem to be able to find one. My books show a break down but no numbers
 
You can get the part numbers at Messicks
or CNH but most hard parts are not
available or crazy expensive. Still a
good reference. Diagram for 723 there
too, just poke around until you learn how
to find stuff.
Messicks 712 Loader
 
(quoted from post at 14:36:20 05/21/22) You can get the part numbers at Messicks
or CNH but most hard parts are not
available or crazy expensive. Still a
good reference. Diagram for 723 there
too, just poke around until you learn how
to find stuff.
Messicks 712 Loader

I again appreciate it. Looking at that picture for the loader pump, mine has a flange on it for the outlet. Ill have to get better pictures
 

I believe this is correct from looking online. I will look at sourcing. I am leaning that its more the pump than relief but I dont know hydraulics that well
 
Plot your flow vs pressure figures on a piece of paper in 500 PSI increments. Then plop those numbers in Excel and graph them. A bad pump will have a proportional drop in flow as the pressure increases. A faulty relief valve will *usually* look like the example shown, where it will stay closed until it starts to open prematurely. Unless the relief valve has a blown o-ring on it, then the graph will look similar to the worn pump example.
cvphoto126294.png
 

Is this what Im looking for for a replacement pump?

https://www.link_disallowed/acatalog/UF84052----Front-Mounted-Hydraulic-Pump--Replaces-D1NN600B--D1NN600C--87607369-171564.html
 

Is this what Im looking for as a replacement pump?

https://www.link_disallowed/acatalog/UF84052----Front-Mounted-Hydraulic-Pump--Replaces-D1NN600B--D1NN600C--87607369-171564.html
 

Is this what Im looking for as a replacement pump?

https://www.yesterdaystractors.com/D1NN600B_Hydraulic-Pump_2886.htm?gclid=Cj0KCQjwm6KUBhC3ARIsACIwxBhotJHh4ZQz98iEN_ONlhcvTW_y0uyZlz7HPsMfFaDVh5n7-LFTOIAaAsfaEALw_wcB


Can find one at Walts for $500
 
I think that one's for the later
generation 3-cylinder tractors.

Be careful out there, do you have a
splined shaft or keyed? In the 723 parts
book 290346 is 15.5 GPM keyed, 290345 17
GPM spline. However your pump looks kinda
square and those are more oval. The
square-looking front pump for the 4140 is
292551 but the inlet fitting is wrong.

How about pulling the pump, disassembling,
and inspecting for wear and/or other
defects with possible repair in mind?
Also look for a part number and
manufacturer mark.

Otherwise you must note all
characteristics when trying to find a
replacement: shaft type and diameter,
spline count, inlet and outlet fittings,
direction of rotation, displacement, GPM,
mounting arrangement and so forth. You're
probably not going to find a perfect
match, may have to make some adaptations.
 

I really appreciate the help. I think my next step is taking the pump off and maybe even opening it to see if anything is obviously wrong. If not I may take it to a shop to see if it can be rebuilt
 

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