Fel stopped working

[piper184]

Now enter the FEL and it's control valve. There are two spools, one for lift and one for bucket curl. When both spools are in neutral the fluid entering the valve is blocked from the cylinders and must go somewhere. It dumps back to "tank" through the out port. I think this is called an open center system. When either spools is moved in either direction, the tank port is blocked from the incoming port and fluid must pass through the cylinders. The side of the cylinder that is collapsing is open to tank so that the fluid leaving the cylinder has some place to go.

But in this system, there has to be a relief valve so that when a cylinder is at the end of travel the pump does not deadhead. Remember the in port is blocked from the tank port. The relief valve takes care of this by dumping excess pressure back to the out (tank) port. This is the valve that limits the pressure available to the FEL cylinders. It works just like the relief valve in the 3 point controller. Too much pressure lifts the valve off the seat and the excess fluid dumps out the back side. I don't remember if the OEM valve is set by shims or an adjustable screw.

In any case, all fluid from the pump must either go to a cylinder or be dumped back out the "tank" port of the FEL valve. Either by the spool or the relief.

Once it exits the FEL valve it goes back to the tractor and into the priority valve as if the FEL didn't exist. So, as set up by the factory, the FEL can steal pressure/flow from the rest of the tractor, because it is first in line. While lifting the loader the large end of the cylinder is filling while the small (capacity) end is emptying. This means that the loader is consuming more fluid than it is returning and you can short change the steering system for a small amount of time. Once the cylinder motion is stopped by the valve or hits the end and the relief opens, then all flow again is available to the rest of the tractor.

I have occasionally experienced this while lifting and trying to turn at the same time. You will feel the feedback in the steering wheel.

I upgraded my OEM valve with one from Ranch Hand Supply years ago. Best thing I ever did for the loader. The OEM valve is not made very well and it has lots of issues. Looking just now at the manual, it does not show the relief valve. I am pretty sure that I still have the old valve somewhere int he shop. I will try to find it tomorrow and see if I can get some more info for you about the relief valve.

If none of the FEL functions work, it is likely something to do with the relief valve. That is the common denominator.

Since the rest of the tractor hydraulics seems to be working, the pump and tractor relief valve is probalby just fine as well as the suction filter. Although it never hurts to replace a filter, just to be sure.

Until tomorrow...

 

[Jimmy254]

Thks. Thats gunna take me a while to digest. In the meantime i confirmed flow thru the quick connect from pump to loader. As reputation the QC has indeed failed. I spent an hour trying to separate the male and female ends to no avail so its stuffed but i believe the flow was going through as i could blow air thru it. I think im just guessing now so ill look at replacing those QD's and buying a pressure gauge and tee fitting to see whats going on before and after the controller. Please keep any advice coming as i have a nightmare run with this tractor but i will get there.

 

[Jimmy254]

good post. Makes sense.

How can i 100% confirm its the controller? Can it be done using a pressure gauge? What readings are to be expected.

could a flush out be worth a try?

Could i borrow the backhoe control to troubleshoot somehow?

Should i remove and try and clean the loader controller. Has anyone done this?

Should i just bite the bullet and buy a new one and just hope.

 

[piper184]

Sorry for the delayed response. I was able to find the old OEM loader valve but didn't have time to take it apart. Here is a picture of the bottom end.

I think the hex cap is actually the relief valve adjuster. There is a jam nut just under it. The whole assembly is held onto the main body with 4 cap screws. The other two dome shapes are covers for the spool valves.

If it were mine, I would start by backing off the jam nut several turns and then turn the hex cap. Put a mark on it and count the turns. I would try one or two full turns and test. Never having had one apart, I can only imagine that there is a spring inside that holds a pop-off type valve against a seat. adding spring pressure will increase pressure available to the loader cylinders.

If a couple of turns does noting, then I would back the cap all the way off and see what comes out. Do this carefully as it is likely to fly apart under spring pressure. Also lay out the parts in order so that you know how to put it back together.

The first things that come to mind are a broken spring or dirt under the seat of the valve. Next to check would the the valve face and seat are worn and leaking. Spray some brake cleaner or even WD-40 up into the seat to make sure it is clean. Re-assemble and test again.

Since both sets of cylinders are working, it is unlikely that the problem is in the spool valves, but not totally impossible.

You asked about using a pressure gauge. Putting one in the system at either quick connect will only show you the pressure of the system that is controlled by the relief in the 3 point control. To test the pressure to the loader cylinders you would have to tee into the lines that go to the cylinders. Jinma has used different style fittings over the years and you can't tell which one it is until you take them apart. Finding adapters might be pretty difficult.

Remember, the fluid only passes through the open center on it's way back to the tractor unless the loader valve sends it to the loader. The loader relief sets the working pressure for the loader cylinders (up to the limit set by the 3 point relief) and acts as a safety relief for when a cylinder bottoms out,

 

[Jimmy254]

Thanks for your response. I will try a couple of turns of that hex nut first and then clean it if I have to. I managed to buy a tee and a gauge and fittings so I can test at the rear remote or between the pump to loader valve or between the loader valve to priority valve but not the loader cylinders. If I were to tee in at the Quick connect between loader valve and the priority valve should that pressure reading change when the loader is operated or is pressure always constant as set by the 3point relief valve?

 

[piper184]

Most likely you will see a drop in pressure as the cylinders move Then return to the previous setting when it bottoms out or the lever is moved back to neutral.

I've never done this test so can't say for sure what it will show.

 

[Jimmy254]

I put a new hydraulic filter on with new fluid. I tightened the pressure relief valve on the loader controller two turns. I put a tee fitting with a gauge on the line from the pump to the loader controller. I ran the tractor. No change. Gauge was reading around only 200psi. When the steering wheel was turned to the left or right the pressure gauge showed up to about 1000- 1400psi. Holding the pressure at around 1000psi meant I could lift the loader gradually. Could not curl it however. I stopped the tractor. Topped up the fluid. It was low due probably to air pockets which had since gone. Tried it all again. The bucket curl was all the way down. As I was trying to curl it up while moving the steering to and fro it suddenly started working. I backed off the pressure relief two turns. It all tests ok. Looks like pressure is 200psi until either steering or loader is used.

 

[Jimmy254]

I'm none the wiser what caused the issue but my money is on a dirty relief valve at the loader just as suggested. Thks for your help.

 

[piper184]

Now you have me scratching my head...

Does it still only show 200 PSI after it started working?

IF it is is plumbed the way I believe it is, then the problem was most likely at the 3 point relief valve, otherwise you should be seeing full pressure at the pump when nothing is moving. Lower of course if the RPM is down, but definitely more than 200 psi.

In any case, as long as it is working properly, the rest is just not all that important. Until it happens again.

weird indeed.

 

[Jimmy254]

I was confused too. I thought the pump was dead but everything is working. My theory is that while the hydraulic fluid is not being diverted to any function (power steering,FEL or 3pt) the pressure is low and the flow is high. Bit like a 1inch water hose seems to have less pressure than a half inch hose but it takes less time to fill a bucket. As soon as a function is used the pressure in the entire system jumps due to the restriction being applied. Where the restriction is applied is like putting your finger over the end of the garden hose to squirt someone. It increases pressure all along the hose but where it comes out is usable pressure. I don't know if the pump increases flow if engine revs increase. I could be wrong of course.