Ford 640 hydraulic failure

Hello!

I just picked up this 1954 Ford 640 with loader last week. The hydraulic manifold was replaced prior to sale. It always starts on the first bump and appeared ready to work.


The most significant issue on delivery was a minor hydraulic leak from one of the rams and a less minor leak from the other. I fully extended the rams, polished off much of the corrosion, and gave each of the packing nuts a little less than a quarter of a turn to snug the seal up. This appears to have done the trick, one leak is gone and the other is drastically slowed.

I then topped up the fluid to the dipstick with the loader rams extended, and started the tractor up.

Everything worked fine for 20 minutes or so but three times, all the hydraulics would just quit. Moving the selectrol switch and the control valve both don't do anything to the loader or 3 point. Turning the tractor off and back on actually brought the hydraulics back a few times, but now they are dead and I can't get anything out of them, had to drag the bucket across the lawn to get it back in the shed.

The selectrol lever feels a little sticky so I'm wondering if I've torn an o-ring or something in there. I don't think it's the pump as the hydraulics seemed reasonably quick and strong when working. I think it's a little suspicious that it started immediately after servicing, could I have overtightened packing nuts or something?

Tomorrow I will try to verify the pump pressure at the outlet port on the pump, what other sort of things should I be looking for to narrow this down?

Thanks!

For the selectrol valve to work the 3 point
lift handle must be in the up position.
Sometimes if the friction washer on the
lift handle is loose the handle will drop
on its own.
If no pressure at the pump I would try
bleeding it.
If you do have pressure at the pump I would
hook the guage up at the output of the
selectrol valve. That might tell you which
of the two valves isn't working.