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I have a 2005 lenar (dong feng) LE204A I have never had the lift control or cylinder apart, being a 2005 I am concerned about pulling it apart and finding that the parts are NLA. If there is anyone who has a tractor similar to mine could you please chime in if you have any experience with the lift system. It does not have a draft control. basically a up, down and hold position . I have looked at the parts book and I see several possibilities. really the only thing I have verified is that when the fluid control knob is turned in (off) the lift arms still creep down slowly. But since I do not know the hydro circuits path I do not know if that means anything. Thanks
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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?
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I would say with a 5 ft. finish mower from fully up to on the ground less than 5 min., it was something I thought I would address before it got bad. When I run a tiller sometimes I do not want it to run at the full depth on the first pass so having the arms not sink is good. most when the wife is running it, if you know what I am sayin.
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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)
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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.
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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?
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sorry it took this long to respond but as you asked I rose the lift arms all the way up closed the flow valve and lowered the lift control and I guess they fell at three to four times faster than the speed if I let them fall in the hold position. curious , I emailed DFAM in China and asked who here was a seller of their parts and have not heard anything yet. not holding my breath.
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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….
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