640 3 Point Won't Go Down

Montana55 · Feb 10, 2016

After my 1955 Ford 640 sat for 3 months, it took 5 minutes of running to get the 3 point back blade up. Now that I got it up, it won't go down. It has been sitting there shut down for 3 hours and it's still up with the lever all the way forward. I tried working the lever several times but no response. Last summer it worked great and I changed the transmission oil (it originally had heavy gear oil in it) and replaced it with the special NH oil, then worked it several hours afterwards.
Any ideas?

JMOR · Feb 10, 2016

(quoted from post at 18:35:14 02/10/16) After my 1955 Ford 640 sat for 3 months, it took 5 minutes of running to get the 3 point back blade up. Now that I got it up, it won't go down. It has been sitting there shut down for 3 hours and it's still up with the lever all the way forward. I tried working the lever several times but no response. Last summer it worked great and I changed the transmission oil (it originally had heavy gear oil in it) and replaced it with the special NH oil, then worked it several hours afterwards.
Any ideas?

elow freezing? Warm it up.

old · Feb 10, 2016

Stuck control valve and or depending on how cold it is you may have some water in the system that right now is ice and has things locked up due to the ice. Can you heta it up over freezing then open the drain plug just enough to get a dip if it has water in it??

Montana55 · Feb 10, 2016

It's in the fourties. I think it's had plenty of time to thaw. Where is this control valve that might be stuck? The manual control valve seems fine.

I just pulled it in the shop to tear down the engine to restore compression. It looks like the hydraulic pump tube is in the way of getting the oil pan off so I may have to drain all that NH hytran oil out anyway.

souNdguy · Feb 10, 2016

Hmm.. Lots of issues.

1, hyd pump and plumbing don't have to move to drop oil pan.

2, gear oil in the trans is normal. Trans and Hyds see different sumps!

3, is the 3pt up by pressure or friction. Rusty dirty pin and bushings can keep a empty 3pt up.

If Hyds are keeping it up, crack the plug on the cover under the seat to exhaust oil.

If pump makes flow at startup, but no 3pt, and it sticks up, expect stuck unloaded.

That brings up your trans oil change. If you realm only changed the trans oil, the stuff in the Hyds may be ancient or wet or..

ctfordman · Feb 11, 2016

I would say unload valve is stuck. Fairly common if tractor has been sitting.

JMOR · Feb 11, 2016

(quoted from post at 11:23:48 02/11/16) I would say unload valve is stuck. Fairly common if tractor has been sitting.

ee, you would be saying wrong, because the unloader valve is not at all involved with the flow path used in dumping the lift ram cylinder.

Montana55 · Feb 11, 2016

(quoted from post at 19:41:59 02/10/16) Hmm.. Lots of issues.

1, hyd pump and plumbing don't have to move to drop oil pan.

2, gear oil in the trans is normal. Trans and Hyds see different sumps!

3, is the 3pt up by pressure or friction. Rusty dirty pin and bushings can keep a empty 3pt up.

If Hyds are keeping it up, crack the plug on the cover under the seat to exhaust oil.

If pump makes flow at startup, but no 3pt, and it sticks up, expect stuck unloaded.

That brings up your trans oil change. If you realm only changed the trans oil, the stuff in the Hyds may be ancient or wet or..

had to take a look to refresh my feeble old memory. It was the middle section under the seat with the dipstick that I changed the oil on. I found the plug under the seat and removed it. Oil shot out of there and washed my face, the back blade slammed down like a guillotine. What next?
I have the engine dissassembled now and as you stated, the pan came off without removing the hydraulic pick up tube.

Sean in PA · Feb 12, 2016

What next?

Can't do much in the way of troubleshooting while the engines taken apart, so you either wait until the engine's running again or you do a full R&R on the hydraulic top cover in parallel with the engine work.

JMOR · Feb 12, 2016

(quoted from post at 09:12:20 02/12/16)

What next?

Click to expand...

Can't do much in the way of troubleshooting while the engines taken apart, so you either wait until the engine's running again or you do a full R&R on the hydraulic top cover in parallel with the engine work.

ean hit the nail squarely on the head, with no running, but before it leaves my mind or thread is lost, I will say the with the dump path being so simple, there are only two things I can imaging to impede it. The linkage isn't pulling the control valve (photo, ignore yellow arrow) out far enough for spool to uncover/connect dump ports or debris is blocking path.

640 3 Point Won't Go Down

Montana55

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JMOR

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old

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Montana55

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souNdguy

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ctfordman

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JMOR

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Montana55

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JMOR

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