Ford 8N - Hydraulic System Problem

khopkins · Jul 5, 2015

I have a strange problem that I haven't seen in the Forums. I have an 1950 8N and the Hydraulic system is not working correctly. I did find problems with the piston (rings shot) and the pin that is in the Draft control arm (roll pin) which was broken off. I replaced both and now the PTO will stay up even after the tractor is shut off. Before I replaced them the 5ft King Cutter mower would fall in about 2 minutes. The problem I am having now is that when I try to mow, the cutter will not stay in the right height. I also noticed now that the PTO will not go down correctly now. If I try to adjust the height while in gear it I just can't get it to stay. I took everything apart again and found the pin that rides on the cam had a pretty good wear (about a quarter of pin is flat) so I was going to replace that too, but I am not sure that could actually cause that problem. Has anyone else had this problem and what could cause it?

Thanks in advance for any ideas.

souNdguy · Jul 5, 2015

If your pro is staying up, you have huge problems, sell the tractor!

Pro spins, 3pt lift goes up and down

Cam and follower pin effect resolution of lift..

Sounds like you are in draft mode. If in position control, is your cork friction disc so worn and loose it allows the 3pt handle to move?

Did you adjust the linkages under the cover and clean out the sump, and make sure rod from cover to pump is not bent and moves the valve freely during its short stroke and that grit I not limiting or catching it?

khopkins · Jul 5, 2015

I did clean out the sump and replaced the fluid. I also took off the right inspection plate and manually moved the arm and it went down just fine when I pushed it. I believe the problem is in the linkage too. I do have the lever in position control. I have the linkage all apart right now and was thinking about ordering a new spring. The shaft and assembly doesn't seem to have any wear. The PC handle isn't slipping. It just doesn't seem like it responses smoothly when I move the handle up and down. Could it be something in the Pump? I took the valves and springs out and they looked fine. I can move the piece that goes in the pump (what the control arm goes into) and it is very smooth and has no pressure on it. Oh I also replaced the Pressure Safety value just for good measure.

khopkins · Jul 5, 2015

Can you tell how do you adjust the linkage? I haven't found any docs on that procedure.

JMOR · Jul 6, 2015

(quoted from post at 12:52:40 07/05/15) I did clean out the sump and replaced the fluid. I also took off the right inspection plate and manually moved the arm and it went down just fine when I pushed it. I believe the problem is in the linkage too. I do have the lever in position control. I have the linkage all apart right now and was thinking about ordering a new spring. The shaft and assembly doesn't seem to have any wear. The PC handle isn't slipping. It just doesn't seem like it responses smoothly when I move the handle up and down. Could it be something in the Pump? I took the valves and springs out and they looked fine. I can move the piece that goes in the pump (what the control arm goes into) and it is very smooth and has no pressure on it. Oh I also replaced the Pressure Safety value just for good measure.

I can move the piece that goes in the pump (what the control arm goes into) and it is very smooth and has [u:79b0ea8a43]no [/u:79b0ea8a43]pressure on it." THIS is wrong, because the intake control valve has a fairly hefty spring behind it & should take some pressure to push it & the rocker into/up against pump housing & it should pop back out with spring pressure alone.

khopkins · Jul 6, 2015

Shoot. I guess I have to pull the pump then. There isn't any spring pressure at all. It just goes in and out without and will stay in that position. Thanks for the info. I know my next move.

khopkins · Jul 6, 2015

I might have read your comment wrong. I was talking about the yoke in the pump when the control arm and cover are taken out. Is there a spring on the pump side of the yoke that the control arm goes into?

JMOR · Jul 6, 2015

The rocker lever, is attached to exhaust control valve with a pin, such that rocker can push or pull the EX ctrl valve. However, on the other end of the rocker lever, the Intake control valve is NOT attached to the rocker lever. Intake control valve is spring loaded to push out against rocker lever & rocker lever can push valve into pump body, but can NOT pull it out. The spring behind it pushes valve out.

khopkins · Jul 6, 2015

Okay, Sorry for my misunderstanding in all this. I do need to pull the pump to see what is wrong with the rocker arm linkage since it goes in and out completely free of any tension one way or the other. I can pull it out or push the rocker arm in and it stays in that position. Again I apologize for my lack of understanding. This is my first tractor. I used to work on my own car when I had a 1968 Chevelle and you could actually see the engine, but not anymore. 8^) Thanks for your help. I will let you know what I find.

JMOR · Jul 6, 2015

No apology necessary.........we just need the terminology to communicate. Yes, will be interested in you findings.

Ford 8N - Hydraulic System Problem

khopkins

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souNdguy

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JMOR

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