Three point hitch wont drop

After finally fixing the clutch on my 52? 8n I tried the three point hitch operation. Lift arms raised without a problem, however I cannot get them to lower. The lift control lever (right side of seat) is very hard to push forward while the tractor is running. I left it sit for about 15 minutes and then was able to push it back forward still cant lower the arms. As soon as I engage the Pto (left side arm below seat) the implement lift arms raise even with the lift control lever (lever on right side by seat) all they way forward. Any ideas what to do next. The Hydraulic lift control handle directly under the seat is all the way up. any ideas on what to do next?
 
Remove right side round inspection port and watch inside for movement of control arm and intake control valve on pump as you operated touch control lever.
 
Control arm only moves about a1/4 to 1/2 inch I can move it
more when I grab it then the touch control lever does.
Draining fluid now to see more. Still can’t get the lift arms to
drop they only dropped about a 1/2 over night. Is there a way
to get them to drop so I can pull the top cover. Or am I totally
missing something.
 
Anything you do to open the blue path will relieve hyd pressure and allow lift to drop(of course, if mechanically locked up, relieving hyd will not help). Test port #9 is easiest, but unbolting top cover will open point #6.
2jQjBgv.jpg
 
When I removed the plug from the test port they dropped ad
expected.
Now how do I figure out why they are not dropping I. Their
own?
 
(quoted from post at 12:34:57 06/08/20) When I removed the plug from the test port they dropped ad
expected.
Now how do I figure out why they are not dropping I. Their
own?
3, the exhaust control valve is the most likely culprit. Stuck due to contaminates, corrosion, etc. The way it is made, if stuck, the spring compresses and the spool still does not move.
5xRAYl7.jpg
 

Let me start by saying I am a complete novice when it comes to the hydraulics. I pulled both side plates and the top cover. after draining the old fluid I washed down the inside housing of a lot of sludge. I can now clearly see the rocker arm inlet and exhaust control valves.
How can I check the exhaust port? Do I need to drop the pump now or can I check it without having to drop the pump?
I can move the rocker arm by hand, however I cannot move it with the lift control lever as the control arm does not move it away from pushing on the inlet valve. I am assuming that is because it is not under pressure with the system.
 
(quoted from post at 17:48:20 06/08/20)
Let me start by saying I am a complete novice when it comes to the hydraulics. I pulled both side plates and the top cover. after draining the old fluid I washed down the inside housing of a lot of sludge. I can now clearly see the rocker arm inlet and exhaust control valves.
How can I check the exhaust port? Do I need to drop the pump now or can I check it without having to drop the pump?
I can move the rocker arm by hand, however I cannot move it with the lift control lever as the control arm does not move it away from pushing on the inlet valve. I am assuming that is because it is not under pressure with the system.
ressure has nothing to do with that movement. The only thing acting to move the rocker toward the lower position (intake control out of pump housing and exhaust into pump housing) is a spring behind the intake control valve. The control arm can push against this spring and compress it so as to move rocker all the way up against the pump housing during lift command, but control arm can not pull rocker back away from pump housing. Arm can be relaxed such that the spring can push intake control valve out of pump housing and thus the rocker away from housing and as a result push the exhaust valve spool into the pump housing, resulting in lowering. Control arm can push but not pull.
 
That makes sense wasn't sure how it operated.
I assume my next step is to drop the pump to fix the exhaust valve?
Or is there another way to test?
 
update on the problem. I removed the top cover, pto shaft, and dropped the pump. Finally figured out that both the inlet and exhaust valves were stuck. Took them apart and cleaned the unit, reassembled the valves and they are now operating freely. Hopefully I can put the 8n back together this weekend and test.
Just need to find a gasket set that I can get here by then.
 
(quoted from post at 18:38:49 06/10/20) update on the problem. I removed the top cover, pto shaft, and dropped the pump. Finally figured out that both the inlet and exhaust valves were stuck. Took them apart and cleaned the unit, reassembled the valves and they are now operating freely. Hopefully I can put the 8n back together this weekend and test.
Just need to find a gasket set that I can get here by then.
Good for you! You will be successful.
 

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