ghidley
New member
I have a 2007 354 Jinma (4 cylindar engine) with a 3PH problem that just started (after 8 years of working just fine). My Jinma has the single lift lever with the draft feedback mechanism using a rod to affect the lift control valve within what Jinma calls the distributor. The hand lever and rod feedback work together to control the lift control valve.
My problem is that from one day to the next, my rear lift would no longer stay at the level I set it with the lift lever. The lift arms rise with the lift (hand) lever, but at any raised level, the lift arms then cycle down from that position about 6 inches and back up again, seemingly triggered by draft control ... cycling does not stop until lift lever is fully lowered (and lift arms go back down). All other hydraulics work just fine (loader, steering, and top and tilt -- using a hydraulic remote kit from Ranch Hand Supply). Lift has worked fine for the last 7 years but just last month stopped working. I lift a 72 inch box blade, post hole digger and Jinma chipper. No mowing or plowing.
After making sure this wasn't a fluid level or loose hose fitting problem, and noting the adjusting valve (in front of lift housing), when closed, stopped all flows to lift (no raising), but if lift was already raised and then the adjusting valve was closed, lift arms would still go creep down (with box blade attached), I ordered a lift piston rebuild kit and did the following:
I flushed all hydraulic fluid, replaced mesh filter with a new one and replaced cannister filter with a new one. I removed the lift piston, lightly cleaned it with fine emory cloth (lapping it gently around the piston, not along its length), cleaned it, then replaced the rubber O-ring and plastic scraper ring, lightly honed the bore with a fine bore tool cleaned everything and reassembled, refilled with hydraulic fluid (AW32). Cycled fluid through all hydraulic systems (loader, steering and top and tilt) keeping fluid level filled. Then tested 3PH lift, and the above problem is still present. Old fluid did not look dirty. Old mesh filter had some gunk in it but did not seem blocked.
As the next attempt at figuring out the problem, I checked draft control settings (rod length).
Shortening the rod - the lift arms rise with hand lever, but at any raised level (controlled by lever) lift then cycles down from that position about 6 inches and back up again, seemingly triggered by draft control ... cycling does not stop until lift lever is lowered (and lift arms go back down).
Lengthening rod - same behavior as above, but "top" level seems to be lower (e.g. lift arms do not go as high, but still cycle down and up)
With draft control disconnected (took the rod out), any small lifting of lift handle results in a full raising of lift arms to the top ... and they stay there. If I move lift handle further toward the top, engine bogs down as if hydraulics are pumping against immovable load. Only by lowering the lift handle all the way down do the lift arms lower.
I took off the draft and lever control cover from the distributor case, noted draft control shaft was very hard to turn (not frozen but took a lot of leverage to turn it). Repeated turning of that arm/shaft with its housing on a bench in a vise using a larger adjustable wrench to rotate the lever did seems to loosen the shaft up a bit. Small draft control shaft outside lever itself seemed to be bent a bit inward (toward the housing). The mechanical linkage driven by the lift arm and draft rode linkage appears function (nothing broken or loose inside the housing). I also removed the distributer and looked at the two pressure relief spring/valve assemblies on the top - unscrewed them and springs, shims and needle valves at end all look clean and functional. Have not yet removed other valve assemblies from front of distributor.
All the above was done with adjusting valve slightly open (one and one half turns counter clockwise from the closed position).
Any feedback or advice would be appreciated. Am not sure what to do next other than to continue to take apart the distributor assembly.
thanks
greg
My problem is that from one day to the next, my rear lift would no longer stay at the level I set it with the lift lever. The lift arms rise with the lift (hand) lever, but at any raised level, the lift arms then cycle down from that position about 6 inches and back up again, seemingly triggered by draft control ... cycling does not stop until lift lever is fully lowered (and lift arms go back down). All other hydraulics work just fine (loader, steering, and top and tilt -- using a hydraulic remote kit from Ranch Hand Supply). Lift has worked fine for the last 7 years but just last month stopped working. I lift a 72 inch box blade, post hole digger and Jinma chipper. No mowing or plowing.
After making sure this wasn't a fluid level or loose hose fitting problem, and noting the adjusting valve (in front of lift housing), when closed, stopped all flows to lift (no raising), but if lift was already raised and then the adjusting valve was closed, lift arms would still go creep down (with box blade attached), I ordered a lift piston rebuild kit and did the following:
I flushed all hydraulic fluid, replaced mesh filter with a new one and replaced cannister filter with a new one. I removed the lift piston, lightly cleaned it with fine emory cloth (lapping it gently around the piston, not along its length), cleaned it, then replaced the rubber O-ring and plastic scraper ring, lightly honed the bore with a fine bore tool cleaned everything and reassembled, refilled with hydraulic fluid (AW32). Cycled fluid through all hydraulic systems (loader, steering and top and tilt) keeping fluid level filled. Then tested 3PH lift, and the above problem is still present. Old fluid did not look dirty. Old mesh filter had some gunk in it but did not seem blocked.
As the next attempt at figuring out the problem, I checked draft control settings (rod length).
Shortening the rod - the lift arms rise with hand lever, but at any raised level (controlled by lever) lift then cycles down from that position about 6 inches and back up again, seemingly triggered by draft control ... cycling does not stop until lift lever is lowered (and lift arms go back down).
Lengthening rod - same behavior as above, but "top" level seems to be lower (e.g. lift arms do not go as high, but still cycle down and up)
With draft control disconnected (took the rod out), any small lifting of lift handle results in a full raising of lift arms to the top ... and they stay there. If I move lift handle further toward the top, engine bogs down as if hydraulics are pumping against immovable load. Only by lowering the lift handle all the way down do the lift arms lower.
I took off the draft and lever control cover from the distributor case, noted draft control shaft was very hard to turn (not frozen but took a lot of leverage to turn it). Repeated turning of that arm/shaft with its housing on a bench in a vise using a larger adjustable wrench to rotate the lever did seems to loosen the shaft up a bit. Small draft control shaft outside lever itself seemed to be bent a bit inward (toward the housing). The mechanical linkage driven by the lift arm and draft rode linkage appears function (nothing broken or loose inside the housing). I also removed the distributer and looked at the two pressure relief spring/valve assemblies on the top - unscrewed them and springs, shims and needle valves at end all look clean and functional. Have not yet removed other valve assemblies from front of distributor.
All the above was done with adjusting valve slightly open (one and one half turns counter clockwise from the closed position).
Any feedback or advice would be appreciated. Am not sure what to do next other than to continue to take apart the distributor assembly.
thanks
greg
...