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Based on that, I would say you have a problem in the control valve. I would bet there are no seals on the spool and it works only by close tolerance fit. These valves are not know for high quality tolerances in the first place and yours is likely worn some.
This is based on the concept that there are two ports into the cylinder. One from the control valve for pressure feed to lift and the other for the fluid to escape for lower. The second would take the path through the speed adjust knob (needle valve?) back to the control valve. This is also under the belief that the control valve has the pressure relief valve and the return path to the tank.
IF the speed knob is working properly and can close off the return path then the only way for the fluid to escape the cylinder is to leak past the piston or backward through the control valve. Since the position of the control valve affects how fast it leaks that would indicate the control valve is the culprit.
Of course the piston seal could be leaking too….
That’s a bummer. If you compare your parts diagrams to the one for the Jinma 254 do they look the same?
With the flow control valve screwed in all the way to the stop position and the control lever put in the down position does the lift lower at the same rate as it does with the lever in the hold position?
You’re probably fine with the AW-46. I don’t see that changing to even 100 would do much for the leak-down except to maybe make it take 15 minutes instead of 5.
Unfortunately I don’t see any option other than dis-assembly and inspection. It looks like just O-rings and gaskets. The O-ring sizes are listed in my parts book. If they are in listed in your parts book you can search online for them. Circle-G has a good online parts book. The gaskets can be made by hand if needed so lack of availability shouldn’t be a concern.
Even if the spool or bore are damaged and replacements are not available you should be able to reassemble what you have. Same goes for the piston and cylinder itself.
Looking at the parts diagram for the control valve it would appear that you have to take it all apart to inspect the spool and bore.
Yeah, something is definitely leaking.
I would be inclined to take the block that holds the flow control knob off and have a look inside. It may be one of the o-rings and you may get a better idea of how it works.
You might also be able to pull the cylinder and piston from there. If not, it is quite a pain to take the whole assembly off of the differential and flip it over to get the cover off.
I think you can get the spool valve out of the control without taking it off the tractor.
Don’t forget to drain the fluid. 🙂
Speaking of which, how heavy of a fluid are you using in the summer? I run pretty thin stuff because it is so slow to warm up in the winters of ND (which is most of the time I use it)
Hi Jeff,
This thread is 3 years old, I had to go back and review it to even remember what it was about. If I remember correctly I was able to fix mine by spraying some brake clean and then some lubrication onto the balls that sit between the steel discs. Once they started moving freely all I had to do was adjust free play and all was well.
Do you have disc brakes or drum brakes?
What kind of work are you doing to the brakes?
Most 3 point systems will eventually settle to the bottom.
I’ve never seen a hydraulic schematic for these tractors but if I understand it right, the fluid flows in one port (from the master valve) and out though another port (past the speed control knob/valve.
Based on the quality of machining on these valves, I would bet it it is leaking back past the master valve. About the only other place for leakage would be the piston/cylinder seals.
There are seals between the piston and the cylinder as well as between the cylinder and the “head” (where the flow control knob is). These seals appear to be just O-rings and both are the same size. There is also an O-ring at the open end of the cylinder, but I am not sure what it would be sealing against.
Having never had my system apart I have no specific advice other than to take it apart and inspect for damage to surfaces.
How quickly does yours leak down with a moderate load on the lift? Over night or in only a few minutes?
Not likely to be the voltage regulator. What relay did you order?
Have you traced the power from the battery cable from point to point starting at the battery? Either a 12v test light or a volt meter or multi-meter will do the job.
Fuse blocks on these tractors are notorious for bad connections. even though the fuse is good, the wiring connector may not be.
Another known weak spot is the key switch. Have you tried the run position to the left instead of the one on the right?
Do you have a wiring schematic to follow?
Did this symptom just start or is there a history of electrical issues?
Personally I would start at the power feed to the fuse block. IF that is dead, work my way back towards the battery until I found power. If there is power at the fuse block I would test at the ampmeter and the key switch then follow outward until I found the fault.
The positive battery cable runs from the battery to the starter, all the rest of the electrical system flows out from the starter and that is an easy place to access.
An old axiom of electrical system troubleshooting is “check the grounds, check the grounds, check the grounds”. All power flows back to the battery through the ground wire that is attached to the frame. If that connection is bad nothing works. Take the bolt out of the frame and sandpaper the frame and cable lug to make them shiny then re-assemble.
Let us know what you find and we can go from there.
There is most likely one or more adjustments for your clutch depending on what make and model of tractor and what options came with it. The most common is a Jinma or derivative with a two stage clutch for a live PTO. There would be 3 different adjustments on that style of clutch.
The symptom you describe does not usually indicate an out of adjustment condition. The first and easiest thing to check is the roll pin that connects the bell-crank to the shaft that goes through the bell housing. This is a known weak point on Jinma tractors. The roll pin can shear off internally and it is hard to detect from the outside.
With no pressure on the clutch pedal, make a witness mark across the end of the shaft and the bell-crank. Use a marking pin, some paint or just scribe a line. Then have a helper push the clutch pedal all the way in while carefully watching the witness mark. Any movement between the shaft and the bell-crank indicates a problem with the roll pin.
If that all looks OK, you are going to need to take the inspection plate (or the front end loader bracket) off and have a look inside to see what is going on. You need this access to make the internal adjustments anyway.
Do you have the operators and/or parts manuals for your tractor?
As I understand it, yes, a 3 point lift piston can come out of the cylinder (inside under the seat) and get cocked at an angle and won’t go back in.
Do you have a parts book that shows the parts for the 3 point? If not, go to one of the dealers such as Circle G or Affordable and look up the 3 point piston. That will show you how things go together.
If you drain the fluid and take the back cover off, you may be able to see what is going on inside. You might get lucky and just have to lift up on the arms enough to get things back in place.
That sensor is for the tachometer. It detects the teeth of the flywheel going by so that it can calculate engine RPM.
I see that you have a mechanical oil pressure gauge. I am betting that is not factory.
Here are some pictures of the glow plugs. They sit between the injectors and the valve cover.
Also there is a good one and one that came apart during removal. That was a long story in itself.
