Finally back to work on my 4000 - Hyd Issue

Well after a busy spring, summer and fall I'm back to work on my baby.
1964 Ford 4000 Ind. SOS.

3pt lift arms will not pick up.
Hyd Pump will not self prime, and when I apply 5lbs of air to dipstick I get flow, but no pressure.

Proofmeter works fine, so I know the gear is spinning.

System worked well before the rebuild, but I would have to purge air from the pump from time to time.

Question is, has my pump finally gave out/stuck? What else to check before I take it off and see about having it rebuilt?

What was rebuilt?

I'd be interested !! Where are you at ??

Sean it was last winters project. Basically, my crank was worn to the point we just replaced it, and during the split we fixed all of the things that had been neglected over the years.

Here is my original thread. http://forums.yesterdaystractors.co...&postdays=0&postorder=asc&start=0

The pictures aren't showing up.

Here are some before and after pics. http://forums.yesterdaystractors.com/viewtopic.php?t=1209946&highlight=

Had to split it a 2nd time to replace the front seal on the trans. And had to replace a hyd manifold due to overtorque and breaking an ear off the original.

With air applied to the reservoir I get flow through the pump, but as soon as I take the air hose off i get nothing out the pump. And even with the air applied, all I am seeing is the pressure from the air hose, no pump pressure/volume. I have a 3/8 nipple and valve screwed into the top of the pump so that I can dump to a bucket to figure out the problem, this is what I was using to bleed the air off of the system prior to the split/repair.

The lift seemed to work when we first put it back together, but now it does not, and no fluid through the pump. I was worried about a line being plugged until I put air through the line and got nothing but clean fluid out.

I was just asking because in the first post you talked about the symptoms with the hydraulics, then said something about said "after the rebuild" and then asked if we thought the pump needs to be rebuilt.

Since you say that you replaced the hydraulic manifold, my first suspicion would be there. Did you replace it with a used one? Did you check it for a true flat surface where it meets the front of he transmission? Might just be sucking air around the suction tube.

Yes it was a used Cast Aluminum manifold, with new o-rings, and I don't have any drips from that area when the tractor is off. I didn't have any drips when pressure was applied either.

The lift worked briefly after re-assembly, prior to me hanging the lower lift arms back on the tractor and hooking them up.

Prior to any work we did, we had issues with the pump losing prime from time to time and having to be bled off, just wondering if the dry time during the rebuild (in the barn on the shelf for 3 months) and then reassembly might have had some failure or stuck part in the pump itself now.

Don't know enough about the pumps themselves to know if there is something else to check or try before I take it off and send it to the shop to be rebuilt.

Like I said, I can open the plug on top of the pump, start the tractor and I get nothing, the proofmeter works, so I know the gear is spinning, but unless I add air pressure to the reservoir I get no fluid out the pump, and then its just at the pressure I apply, not from the pump actually displacing it under pressure. As soon as I shut the air off, the fluid stops.

Before I would have to start the tractor and crack the valve for a second and get a shot of air, then fluid and when I closed the valve I would have hyd pressure to the lift.

So I guess the question is, is there a valve inside the pump that could be stuck open, and can it be fixed without rebuilding the pump itself, or have I possibly damaged the pump by letting the tractor run with the pump dry.

I probably don't have much over an hour of total run time on it since putting it back together, chasing down other small issues and life getting in the way for the most part of the summer/fall so far.

There are 6 pistons inside the pump that get actuated as the wobble shaft spins, and each piston has a one-way valve consisting of a ball and a spring pressing the ball into a seat. It is possible that all 6 valves have gotten stuck while the pump sat dry for that amount of time, or that the springs were weak to begin with and they rusted while sitting dry and then they broke when you started it up after putting it back together. But unless you intentionally did something to get all of the oil out of the pump when you removed it from the tractor, I don't think that it really was "dry" inside.

It won't hurt to get the pump rebuilt, just don't want to see you spend money if you don't have to.

Another trick to try is to park the tractor facing down a hill with the hydraulic reservoir topped off to the full mark on the dipstick, so that the pump is lower than the level of the fluid in the sump, and then run the engine for a few minutes like that. If it is going to prime and work, that will usually do it.

Thanks Sean, once it stops raining someday..... I will give that a shot, have a couple of spots in the yard that I should be able to get the propper grade to try that.