|
HUNDRED SERIES HYDRAULIC TROUBLE SHOOTING First you must determine if the pump is pumping correctly. Most of these round later pumps have two plugs in the pump The one closest to the front of the tractor and in the head of the pump is the one you use to bleed the air out of the pump after air has entered the pump. Air can enter the pump from a bad pump shaft seal and or bearings and it can also enter the pump through a leaky intake O ring or a small hole in the intake pipe. If the hole is above the oil level it will not leak when standing. Usually if it is below the level of the oil the oil will leak out slowly and make a puddle under the tractor according to how big the leak is. If the pressure side leaks it will not make air go into the pump but will cause a loss of oil. If it does have the two plugs then one toward the rear of the pump is for priming only. Pour in some oil. Take the front plug out and start the tractor and run until the oil that is escaping the bleed hole is free of air bubbles. Then shut down and replace the plug and the pump should be operable. There is the chance that the gear that is the pump driven gear has stripped out it's spline in the center of the gear where it fits onto the pump shaft. This does happen but now often. I suspect that cold oil and a leaky pump shaft seal may be the problem. It is hard to fix the pump shaft seal if it is in fact leaking. A special tool is needed to pull the roller bearing race cup and the old seal if you save the old race. You can get that race out by welding a bead all the way around the face of the race and let it cool and then it will come out easy as it is shrunk. Then you can drive out the old seal and the old needle bearing. Dirty job but it can be done/ If it is determined that the pump is operating right and supplying enough volume of oil under pressure to the hydraulic system then you may have a sticking unloading valve in the lift ram cylinder housing. 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. 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 N 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.
Zane
| 
