Hydraulics on 601

Trying to troubleshoot what is wrong. Not my tractor. The owner said the hydraulic pump was rebuilt about five years ago. I was told they had to prime the pump every few days by blowing air in the dipstick hole. They parked soon after till last month.

I got it running and blead the pump. The 3pts arms go up but are very slow and vibrant a lot.

I swapped the pump with the one off my 4000. The 601 acted the same with my pump.

I'm thinking the 601 has a valve sticking under the top cover?

If the pump is loosing it's prime when sitting it is either a leaky O ring in the intake side of the manifold or the pump shaft seal is leaking allowing air to be sucked into the pump when the oil drains back to the sump. Replace the pump seal is likely going to be needed.

On the 53 and up Ford tractors there is a gadget named the unloading valve. It is hydraulically shifted by the movement of the control valve. The control valve does not actually move oil to the ram cylinder. The oil is directed to the ram cylinder by the position of the unloading valve.
If and when the unloading valve stops moving then the lift won't lift until the problem that is causing this condition is fixed.
A faulty back pressure valve can cause the unloading valve to stick.
The unloading valve can stick on it's own.
The unloading valve has an O ring that can become worn until it will not allow the valve to move.
The pump could have lost it's prime too. The piston pump must be bled by opening the front head plug in the pump and running the engine slowly until all air bubbles are gone from the escaping oil. Stop the engine, replace the plug and start the engine again to see if that fixes the problem. It can!


I would first try bleeding the pump by removing the front pipe plug with the allen head hole in it. Start the tractor and let it idle as slow as possible and when all the bubbles are gone stop the tractor and put the plug back in. You will loose about a half cup usually so put something under the pump to catch the oil.
If it won't work then you must go into the lift and take out the unloading valve and clean it up and replace the O ring with the Ford O ring made specifically for the unloading valve. The old part # was NCA 836B. Don't use a substitute or you will be sorry.
The unloading valve is covered by a plate at the front of the control valve housing just above the control valve. Their is a plug over the valve that must be pulled by inserting a bolt with fine threads into the plug and prying it out with two bars or an impact puller tool can be used to snatch it out. The valve can then be pushed out with a punch of the appropriate size. Don't strike it with a hammer. The O ring will be on the unloading valve that needs to be replaced.
If you will look around on the other reference pages of the Yesterday?s Tractor?s Ford forum board etc you can probably find some good views of the lift to give you some idea of what you will be looking at.
When taking the lift control housing off the tractor remove only the bolts that are around the ;outside edge of the housing and do not remove any of the bolt that are inside this circle of bolts. If you encounter a bolt that has fine threads on it put it back where you took it out. The fine bolts hold the cylinder to the cover housing.
Good luck.