Loader slow, and underpowered

[KingCord]

I have a 1996 M4700DT with an LA1001 loader on it. Lately the loader has been operating much slower than it used to and it does not have the power it once had. Hyd pump was rebuilt and I changed fluid and filters. Made no difference, pressure check was good as well, so leads me to believe its either a flow issue, or something in the loader valve is acting up. Is there any adjustment in the loader control valve? Like a relief valve, or by-pass, anything of that nature that could be stuck?
Thanks for any help, and info.

 

[Dave_eng]

Any new equipment or feature added such as a grapple or any hoses changed? Have you reseated all quick disconnects

Who rebuilt pump and was this done just in hope that it would solve the issues you have with slow performance?

Tell us about the pressure check you did and how you did it.

Usually when pumps fail or get worn out the pressure they can deliver drops off. Your comment about "the power it once had," seems out of sync with the hydraulic pressures being OK.

I don't know your tractor and loader. Do you have a joystick and cables going to the real hydraulic valve?

Something getting loose in the cable system can reduce the movement of the valve spools and slow down the flow.

This is from the WSM of a larger tractor.

Dave M7040

 

[imnukensc]

Read the comments after the video. Insure your 3 pt hitch lever is not pulled past the top.

https://www.youtube.com/watch?v=aqtDqeqbJQw

 

[KingCord]

Rebuild kit was purchased from local Kubota dealer and local hyd shop did the pump rebuild. There are no new accessories such as a grapple or anything of that nature. Pressure test was performed just as described in the service manual. There are no cable linkages in the control system for the loader, and no excess slop in the joystick linkages. Quik connects were all disconnected and cleaned. It's not a pressure issue, it's a flow issue. Just can't figure out where blockage can be. 3 point works fine and is not slow which leads me to believe it's in the loader control valve assembly. Is there a bypass or relief valve of some kind in the loader valve assembly that could be stuck open? I don't have a service manual for the loader so was hoping someone here would know.

 

[Dave_eng]

Can you post a couple of pictures showing your loader valve.

If your pressures are good according to the spec's, then some flow must be going elsewhere.

Again I don't know your model of tractor and loader. Larger tractors send the hydraulic flow to the FEL and then, using a power beyond port, to the 3 pt and rear remotes so, although it is often not clear, there are likely two relief valves.

If the FEL is first in the circuit just as an example, and its relief valve is set too low, then the pressure going to the 3pt and rear remotes, although they have their own relief valve, will be limited by the FEL relief valve.

Sometimes the steering will also be powered by the same hydraulic circuit and have a priority flow control to ensure that steering always has top priority.

Is the joystick mounted directly onto the FEL valve? I was not clear from your reply.

Sorry I am not able to help more. Dealers have WSM's for FEL's and tractors in digital pdf forum. The FEL will have its own WSM.

My dealer gave me all the WSM's for free. Going to see a local dealer armed with a USB stick and a willingness to pay a fee may get you what you need. The electronic pdf from Kubota is much better than a paper pdf as you can blow up images of components to see inside which you cannot do with a paper WSM

Dave M7040

 

[100 td]

Additionally to Dave's post....
First thing, ensure 3pt is down on the ground in float mode or similar so that there is no chance the 3pt is using or relieving any fluid.
Test the function of the boom lift now. If there is an improvement then it's likely the 3pt is going too high and relieving when it's up. (adjustment required)
Is the curl function slow as well?
One of the most common faults for slow loader operation is a faulty quick connect valve. Ensure no residual pressure exists in any line before inspection.
While you have cleaned them, make sure you operate each valve (male & female valves) individually and ensure they are fully seated when you replace them. You may be able to temporarily swap boom and curl functions to see if the problem changes to the other cylinders.
You may have some debris in the quick connects themselves, you can generally unscrew them and check them.
Sometimes when a loader is fitted it is tapped off a control valve which directs the oil to the 3pt, so now it flows out a different port to the loader before returning to the 3pt circuit. This valve could also be faulty, or have the valve rotated the wrong way.
Do you have remotes fitted? Where is the loader tapped from? Is it tapped from the remote valve?
If you have remotes ensure they are properly centered.
Some loader spool valves have a relief valve built in, also your spool could also be bypassing internally, if you are going to pull the spool valve I would buy a full oring/seal kit for it and replace everything while you have it apart.
No idea if this site is a scam or any good, I haven't checked it.

Mod Edit: Scam ad removed.

www.ebay.com/itm/350713022411

 

[scdeerslayer]

Check the pressure at the quick connects.