Slow and Weak Loader on Montana R4944HST

[riderpriderking]

Hi Everyone, long time lurker, first time poster. Thanks for all the great advice that you guys put on here, it's been super helpful. I bought a Montana R4944HST (LS R4020H or McCormick CT 47) from an auction a month ago with roughly 1000hrs. I've identified or fixed a number of issues already and I'll post those in the owning/operating form with their solutions another day. For today though I have a problem and I'd like to run it by some great minds before I go out and buy parts just in case my logic is flawed.

My problem is that the loader is slow and weak. It takes about 20 seconds to fully raise (should take 4) and it would hardly lift a couple hundred pounds at the pins (Specs say >2000). It also got progressively worse as it warmed up. After doing some research on here I went out and bought a pressure gauge and some fittings. In the rear remotes the pressure gauge shot up to about 2500 psi and I heard the relief valve whine so that was all good. When I put it in the loader quick disconnects I got about 600 psi in the raise/lower ports and about 650 in the tilt ports. I also did my best to test the cylinders on the loader but since they were only getting 600 psi I figured that they aren't the issue.

The pressure from the pump goes into a distributing block and then into the loaders directional control valve. I looked in the block and saw nothing that would cause any pressure loss.

As an aside I'll describe the block too. One port comes from the pump. The next is pressure out to the loader valve. Beside that are 2 ports that return from the loader control valve's Tank 1 and Tank 2 lines. These ports are labeled R and T on the block. Not sure what R stands for, regen maybe? On the front side is the pressure relief valve. On the last side is a line to the tank and a line to the PTO which continues onto the rear remotes.

Since I had good pressure at the rear remotes and the HST works fine I don't think it's the pump. I can't see how the block can be bad, and the loader cylinders seem fine, therefore I feel like it must be the valve.

The valve is an older version of a Nimco CV112. It doesn't have a relief valve, it just has a plug, which I checked and the o ring was still on it. I checked the cables from the joystick, they seem fine. The spools move in and out ok. I took the spools out, they didn't show any obvious problems. The springs seemed good. The O rings on each end of the spool were there and intact. No external leakage.

So I feel like the valve is the problem but I couldn't find anything obvious. I'm thinking about replacing the valve with a 2 spool MD 30 valve from Princess Auto (ie Harbour Freight in Canada) which has all the same features and schematics, if the mounting screws were the same I'd just have to take off the joysticks, screw in my joystick cables and get some adapters for the ports. But before I spend $300 I thought I would ask you guys since I'm a little stumped on the exact cause.

Thoughts and second opinions are greatly appreciated! Thanks

 

[100 td]

Slow down on buying a new valve till it's diagnosed. If you have one cylinder badly leaking it could do what you describe. Does it have any quick connect fittings, these are another area for faults from valves not opening properly. If you have QC's, swap bucket and boom and see what happens. When the bucket is flat on the ground, can you dump it and raise the tractor off the ground, or does it lift the boom? Does the bucket curl and dump to spec? I expect the valve also has a relief built in to it?
Take some photos, helps everybody get a handle on it.

 

[riderpriderking]

Thanks for the reply. I'm definitely not into spending money if I don't have to.

I do have QC's but I put the gauge in all 4 of them and they all read roughly the same, around the 600 psi mark. I did try the raise/lower hooked up into the dump/curl ports and got the same slow and weak results.

One positive note is that I was able to lay the bucket flat on the ground and dump it to raise the front wheels off the ground. But I'm not sure how much strength that takes. If I dump the bucket then put it down and try to raise the machine with the raise/lower circuits it can't lift it off the ground. The dump/curl circuits seemed a bit weak when I was moving stuff around, if the loader couldn't raise it, the curl couldn't either.

I should also mention that the tractor was serviced after I got it and has all new fluids and filters so I don't think its a pump strainer or anything like that.

Lastly, I tried putting the bucket down, taking off the hoses running to the lift sides of the cylinders, and then pushing the bucket down to check if any fluid was bypassing the cylinders. There was none coming from the cylinders but I did have some discharging out the lift circuit line from the valve. Not a lot of pressure but a continuous flow. I'm not sure if that's normal or not, it looks like it could be part of a regen circuit but I don't totally understand that.

I attached the photos that I had on my phone for putting it back together, they mostly show how everything is connected.

My theory right now is that either the plug that is in place of the relief valve was leaking pressure or the spools themselves are leaking pressure. Neither of those seem likely or common though.

 

[100 td]

2500 at rear and relief operating is good. 600 up front is not. ~600 on both circuits says something wrong with relief or a shot valve/crack internally I expect, or someone has played. Can you hear the valve relieving when you curl the bucket and hold on curl? Could try a small adjustment of relief and look for a change, could remove tank return line and see if oil is flow to tank when it shouldn't be.

 

[riderpriderking]

Well after taking a couple weeks off to build a shed I'm back at it. I replaced the loader valve assuming that it had to be the problem. It seemed better but still not what it should be. I still can't get the pressure on the loader valves past 1000 psi, which is no where close to the relief valve setting. The rear remotes still hit the relief setting.

Would it be possible that a different valve is leaking pressure and causing the loader valve not to be able to build up pressure? Besides going forward to the loader valve, it also goes back to a pto solenoid and then onto the rear remote valve. The PTO solenoid is sticking, sometimes you have to tap it with a screw driver to get it to turn off. Maybe that's a sign that something else in that block isn't quite right. I'm also wondering if something is just plumbed in wrong. Anyway I'll think about it over the weekend and do some more investigating next week.

I've attached the hydraulic schematic for reference if anyone is interested.

View attachment LS R4020 Hydraulic Schematic.pdf

 

[oldnslo]

The schematic shows this having a gear pump which means the flow must go from one component to the next in series or have some form of priority flow system. Does the loader valve have two lines that connect to the distribution block? One going the pressure port on the loader valve and the other would connect to the power beyond port of the loader valve.

Does the distribution block have to be reconfigured for adding the loader Vs no loader?

 

[riderpriderking]

I think your on to something oldnslo. I pulled the plug above the pressure release in the hydraulic block and it was item number 3 on the front outlet valve diagram. So when there was no front loader, that plug was put into the front side which basically allowed oil to flow from the pump then turn the corner and head to the back of the machine. When they put the loader on that plug blocks the aforementioned path forcing it to go out and through the front loader valve. The plug looks like it's supposed to have a o ring on it. I'm working on ordering a new washer or plug.

It would make sense though, basically it's allowing medium/high pressure by it which is then going into the back side of the loader valve, decreasing the pressure differential. That's also why the rear remotes get full pressure, because it doesn't matter if that particular plug is bypassing or not.

Does that seem to make sense? I'll let you guys know how the new plug works.

Has anyone ever returned a hydraulic valve? Thinking about trying to return the new one and just go back to the original.

 

[oldnslo]

I agree with that plug missing an O-ring. Yes from your description of its location it would cause the symptoms you are experiencing.

 

[ptsg]

That plug should definitely have an O-ring and also a backup ring. My Branson has a similar block and I had to swap that plug to the other position where it allows to add a valve in series with the circuit. And I've noticed not only the O-ring but also a backup ring.

Here is a picture from the manual:

 

[riderpriderking]

The problem has been solved. I installed a new plug from New Holland and we are up and running. It's somewhat frustrating that I spent a lot of time and money for a $20 problem that took 30 seconds to fix but such is life. I guess its the price I have to pay for experience. I've attached some pictures of the old and new plugs. It's exactly as ptsg described. The o ring was just missing.

Thanks everyone for your help, I really appreciate it. I've fixed a few other problems on this tractor too but I'll post those in the Montana form once I get some time.