Farmall M Hydraulic system problem

One Shot

New User
I have a 1947 Farmall M equipped with a hydraulically operated front bucket loader. When I raise the bucket up, it will slowly decend on its own and will not hold in place. Hydraulic fluid also comes out of a hole in the center of the plug on top of the hydraulic fluid reservoir when operating the hydraulic system. Is there suppose to be a hole in the plug? If not, is this why the hydraulic system will not hold the bucket up in place? If so, why won't the hydraulics hold the bucket in place?
 
The probable reason the loader drops is beacause the cylinders that do the lifting have bad seals on their pistons. They are rebuildable. To check the seals put a jack under the bucket so that the jack is extended at least 8 inches.
Lower the bucket to remove all pressure from hoses. Remove the pressure hose from the Liftall and (avoiding loss of fluid) cap it. If the hoses run from both sides, cap both hoses.
Now lower the jack. If the loader drops as before, it is the seals in the cylinder. Local hydraulic shops fix them routinely. If it stays up, the Liftall controll is leaking. (much less likely) The return hoses are probably routed to a T at the fill pipe. If routed to the drain with a close nopple and T they will not squrit. Jim
 
If the cylinders are single action, the leak should be extrenal if they are leaking. Some single actions have a drain hose off the rod end and if that's the case and the cylinder is leaking, oil should comeout that drain hose. If they are double action, capping both sides and doing like jan... says, they are leaking past the piston. As for the hole in the cap, that's a breather for the reservoir. Hole will be cross drilled through the wrench flats and the inside will be drilled to intersect that cross drill. There [u:f0b9941794]should[/u:f0b9941794] be a porous bronze insert inside the cap to keep dirt out.
 
The belly pump reservoir is supposed to be vented when used with one-way cylinders. The hole in the cap is normal.

When one way cylinders extend, they suck oil from the reservoir, and air has to get in. As they retract, the oil gets pushed back into the reservoir and the air has to get back out.

If oil's squirting out, it's because you have too much oil in the reservoir. Only fill the reservoir with the loader completely lowered, to avoid overfilling.

Your hydraulic control has three positions, raise, hold, and lower. Being a 60-70 year old tractor, the hydraulic control valve is probably VERY worn, and you may not be getting it 100% in the hold position. It may also be leaking internally. This may be why the loader leaks down over time.
 
Your problem is how it is plumbed when you move the bucket its taking hy fluid away from the cycls that are holding it up thus letting them down because the fluid holding the loader up goes to the valve running the bucket i had to redo one once that did the same as yours.
 
Dear Janicholson,
When you say "Cap it", am I correct in assuming that you mean to cap it so the cylinders are air tight?
 
Dear Janicholson,
I neglected to state that the hydraulic bucket has 2 cylinders that lift the bucket and 1 cylinder that tilts the bucket. In addition to the bucket lowering on its own, the bucket also tilts slowly on its own. That being said, wouldn't the fact that if all cylinders are not holding indicate that the chances of all cylinders leaking by would be highly unlikely?
 
Yes. The valving you are using may be the real issue. If you test the cylinders successfully the valves may be the source. Farmall belly pumps rarely leak down, valve systems used with them can and do. Jim,
 

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