Loader Valve Leaking Down

[dieselscout80]

My TC45DA factory loader at time drifts down while I am using it.

Is this an indicator that the loader valve needs new o-rings/seals?

 

[Harry in Ky]

No. There are no O rings in the loader valve that have anything to do with holding up a load when spools are in neutral. Spool clearances and load checks do that. While your valve may play a small part in loader drift down, it's more likely a piston seal in one of the loader lift cylinders.

 

[Dman1981]

Easy check for cylinders loader all the way down do this cold and put down pressure so relief goes off for a minute or two at intervals and then touch cylinder where
Piston is if oil is bypassing will be warm to touch
Also can do same thing pull off hose cap it and see if oil shoots out same idea will need pan for oil though be careful if piston seal is totally blown lots of oil
That way you will know if it is a cylinder or a circuit relief valve.
Not all Loader valves have those though

 

[dieselscout80]

Thanks

 

[dieselscout80]

No. There are no O rings in the loader valve that have anything to do with holding up a load when spools are in neutral. Spool clearances and load checks do that. While your valve may play a small part in loader drift down, it's more likely a piston seal in one of the loader lift cylinders.

Sometimes when I start to move the loader control it drops a bit before it goes up.

That said based Dman1981‘s on post it sounds like I may have a cylinder problem.

 

[4570Man]

No. There are no O rings in the loader valve that have anything to do with holding up a load when spools are in neutral. Spool clearances and load checks do that. While your valve may play a small part in loader drift down, it's more likely a piston seal in one of the loader lift cylinders.

A leaking piston seal will significantly worsen a leaking valve but unless it’s pouring on the ground the fluid has to go back through the valve.

 

[Dman1981]

The other thing loader valves have is a load
Check it keeps the oil from leaking back thru so you don’t get the fall when you first crack it
Takes so much pressure to lift poppet off it seat then the pressure is more on lifting side so bucket or loader does not fall first

 

[rScotty]

Sometimes when I start to move the loader control it drops a bit before it goes up.

That said based Dman1981‘s on post it sounds like I may have a cylinder problem.

I don't see how the problem can be in the cylinder. Think about the loader control valve for a moment. Until you move the levers, the control valve is simply an on/off switch in the OFF position. In that OFF position with the the levers sitting in the neutral center position the control valve blocks all flow to and from the cylinders.

Now picture the cylinders. In order for the loader arms to drift down , the lift cylinders have to become shorter, which they can only do by forcing fluid that should be trapped inside the cylinders to go somewhere else. Without a leakage path through the control valve and back to the sump, the lift cylinders cannot shorten and the loader arms cannot drift down.

It won't hurt to look at the cylinders and do some tests, but I think you should also look at the loader control valve. If it is the type of control valve that has a built-in relief valve then that is where I would look first.

rScotty

 

[4570Man]

I don't see how the problem can be in the cylinder. Think about the loader control valve for a moment. Until you move the levers, the control valve is simply an on/off switch in the OFF position. In that OFF position with the the levers sitting in the neutral center position the control valve blocks all flow to and from the cylinders.

Now picture the cylinders. In order for the loader arms to drift down , the lift cylinders have to become shorter, which they can only do by forcing fluid that should be trapped inside the cylinders to go somewhere else. Without a leakage path through the control valve and back to the sump, the lift cylinders cannot shorten and the loader arms cannot drift down.

It won't hurt to look at the cylinders and do some tests, but I think you should also look at the loader control valve. If it is the type of control valve that has a built-in relief valve then that is where I would look first.

rScotty

Like you said the fluid has to leak back through the valve but a leaking cylinder seal will make the problem drastically worse. Instead of having to push a whole barrel full of fluid it just has to push the rods volume of fluid since most of it was allowed to bypass. It would also make the psi in the cylinder considerably higher since the same load is resting on less area.

 

[mikester]

My TC45DA factory loader at time drifts down while I am using it.

Is this an indicator that the loader valve needs new o-rings/seals?

No enough information. There is an acceptable leak down RATE. Are you talking about the loader dropping 4 feet in 1 minute or 4 inches in 1 hour? There is a difference. Quantify please. All hydraulics leak down.