Jimna 354 3 Pt Hitch Hydraulics Problem

[JD600D]

My new (to me) 2003 JM-354 has a problem with the hydraulic lift mechanism for the 3 pt hitch. It goes up just fine, but takes all night to come back down. The valve on the front of the reservoir, (between your feet) is wide open and it is full of fresh clean hydraulic fluid. On this one the control valving is inside the reservoir, not bolted to the side.

This tractor sat for 3 years empty of hydraulic oil, in a bone dry garage. The loader works perfectly and moves at a pretty good clip, so I do do not suspect a pump or pressure problem. Anybody ever heard of this?

 

[quicksandfarmer]

It's not a pump, pressure or fluid problem. The cylinder is single-acting, fluid gets pumped in but it flows out under pressure from the load on the piston. If the lift isn't dropping it's because the fluid isn't flowing out. Either the valve isn't opening fully or something is restricting the flow. The regulator knob controls the flow in as well as the flow out, so if it's lifting fine but not dropping I'd presume the regulator is open, which is what you've concluded as well.

My suspicion is the valve isn't opening. Depending on whether you have the lift box with one lever or two the operation is a little different, but basically the lift handle doesn't directly control the valve. There is a linkage rod between the lift arms and the valve, the mechanism compares the position of the handle to the lift arms and operates the valve accordingly. On my 354 this linkage got quite out of adjustment after a few years. In my case the lift hardly went up, adjusting it got it working properly again.

The linkage is adjusted with a turnbuckle. With the tractor running and the handle in a middle position you can turn the turnbuckle and see which way makes the lift go up and which way down. I would check two things. First, whether you can make the lift go down by adjusting the turnbuckle. Second, when you adjust the turnbuckle you should be able to see how it moves the valve. I'd make sure there are no broken or sloppy pieces in the connection and that the valve is moving as it should. If the valve is moving, and fluid isn't flowing, I would conclude that the valve is clogged or malfunctioning.

 

[JD600D]

Clearly your 354 is unlike mine. Your 354 is of later design, since the control valving is external on yours and inside the reservoir on mine. Nothing outside but a long thing casting with the control levers on the end. It is also clear that this is not a pressure problem since the FEL works as it should and the hydraulic lift mechanism is power up/gravity down so no pressure is needed to drop the 3 point hitch.
Your 354 is of later design, since the control valving is external on yours and inside the reservoir on mine. Nothing outside but a long thing casting with the control levers on the end and a top cover plate under the seat, unlike the newer models.
I think Affordable has the correct manual for me in old stock. It should be here in a few days. I do not need the 3 pt hitch for a week or so, but I would like to make sure that I do not need to order any parts as soon as possible. I may just go in blind and drain the reservoir and pop the cover plate so that I can see if anything is clearly amiss.

 

[quicksandfarmer]

I would say go for it. I've taken mine apart and while it can be challenging sometimes to figure out how things come apart, it's really pretty simple, and if you understand how it works it's not hard to figure out.

One other thing to look at, especially since you said the tractor had sat empty for years. In order for the lift to drop the piston has to move smoothly in the cylinder. If either piece has any rust or deposits it may not be moving freely. That would account for the slowness you describe. On mine there is a 6mm hole in the face of the piston, to take it out you put a 6mm bolt in the hole and use it to pull the piston out. I put the bolt through a piece of plumber's strap and pulled it out with vice grips. If it is rusty it may take some work to get it out.

 

[bjr]

I have the internal valve on my JM354 as well. I had it out this summer. It took two days one to take it apart and one to put it together and it was over 100 deg. days. The sump case is heavy and I used a com-a-long rigged from the ROPS cross bar. Pay attention to the two springs in the bottom as to how they're connected as they're a pain to put back in. The piston oring is available from the local Hydrualics shop the size can be converted from Metric to SAE just fine, measure and look online and you can get the SAE number. The Jinma parts book gives you Metric size on most all of the machine orings just make sure which oring your lookin' at in the book. My particular problem was the lift would not raise fully when hot. Even with new orings I still had the same probem. I finally tried a Lucas Hydraulic Oil supplement and that did the trick. My Walmart UTF oil was just getting too thin when hot. All I can suggest is try to take some high resolution pictures when you get the lid off and the oil out and have a helper for taking the sump off and re-installing. Oh yeah, I just used a the silicone rubber/gasket maker sealant when I went back together the sump and the lid. bjr

 

[JD600D]

Why did you need to remove the sump?

 

[quicksandfarmer]

Why did you need to remove the sump?

Some liftboxes the access to the cylinder is through the bottom, you have to take the box off the tractor to get at it. On mine the access is through the front (ie toward the front of the tractor). There is a plate that comes off that gives access to the cylinder. You do have to remove the gearshift lever to have enough clearance to pull the piston out.

 

[bjr]

Exactly, there are nuts on the bottom side of the sump box you have to remove to get the valve body out and there are o-ring underneath between valve and sump casting that have to go back on when reassembling. bjr

 

[JD600D]

It turned out to be a sticky piston on one of the 2 externally controlled valves. I pulled the cover and syphoned the hydraulic oil out of the sump into a clean can. When I broke the banjo fitting for the pipe heading aft toward the 3 pt hitch dropped to the ground. Upon inspection, both the fluid to the rear cut off valve and the valve controlling the 3 pt drop speed where stuck in their bores. I freed them up and all is well.

On another note, does anyone have a source for CNW (Chinese National Weird) hydraulic fittings? I have a Power Track backhoe going on this tractor and it has a broken female hydraulic hose fitting on the bucket cylinder. It is a flat O ring connection. It has an 18mm x 1.5 thread but it is not a standard ISO thread. My local hose guy had nothing like it. He had a very similar style but it would not thread onto the cylinder. The cylinder fittings are all welded into the cylinders, so changing to some more standard fitting is not an option. I am relatively sure that the chicom dealers can't/won't sell just a fitting.
I was able remachine the barb and sealing surface and braze the 2 pieces back together, so I am good for now. I would to have a couple replacement ends for next time this happens. Any ideas?

 

[quicksandfarmer]

Glad to hear you fixed it. I would start another thread about the fitting. I know there has been a lot of discussion here but I don't remember the outcome. You could also search the archives.