Ford 1700 lift problem (yes again)

[Bender57]

Having some problems, 3 point that will raise and lower but when it is stopped I hear the relief valve. no matter where its stopped.
After a short while 5 min. or less it is real bad and just wont move at all but them out of the blue where it raises and them lowers.
when this is happening the front bucket acts the same as the rear lift. This problem has been with the tractor for some time now but it has gotten worse and to the point cant be operated.
I do have pressure suing gauge until it hits the unloader
The relief valve is clean but no shims
Rebuilt the pump and fluid and filter is clean
I am thinking of going into the spool valve next. Any thoughts

 

[Fawken]

What is your relief pressure (max)?

 

[Bender57]

What is your relief pressure (max)?

2500 psi just before it unloads

 

[Fawken]

According to the service manual your relief pressure should be 2062-2200 psi. It says the 1700 is adjusted via lock nut and adjusting screw (no shims) adjusted at the lift position control valve. I would think the loader relief should be adjusted slightly lower to keep from straining the pump.

 

[Bender57]

But that still does not explain why the overload sounds off when the 3 point is raised and why I loose total hyd a short time after that. Hyd. will come back for 10 seconds then be gone again for longer time say 1 min.
RPM has no effect on the problem

 

[Fawken]

Take a look at your spool valves. The manual I have was pretty lame on them. So I took notes and made drawings as well as marked where the adjustments were before I messed with them. Look first for bad O-rings busted or rusted springs and seats i.e. general dirt. Does your model have draft control?

 

[Bender57]

Yes it has the draft control. I am thinking its in the spool valve. I have had this problem for some time now 2+ yrs and only getting worse.only use the tractor maybe twice a yrs

 

[Fawken]

If it is used that infrequently then it could be as simple as cleaning the ports and seats. When I had problems I checked the spools first, trying minor internal adjustments and reinstalling to see if it made any difference. Mine was ultimately a bad lift piston seal and I found it is the easiest thing to check without expensive jigs and test pumps.

 

[hpweaver]

could you tell me where the filter on hydraulic pump is? I have not opened the cover yet just wondering what all I'm getting into.thanks

 

[Fawken]

In the bottom of the axle center housing is what the manual says. The picture shows it is accessible without taking the center housing apart.