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3-point leaking down

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jnewport2
Join Date: Jul 2011
Posts: 6 Terre Haute, IN
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2011-07-01          179249

I am borrowing a Tractor King JM200 2WD. I was driving it home from my friend's house and just as I pulled in the driveway, the 3-point lost pressure and dropped my box grader to the ground. I raised it back up thinking my hip hit the lever and it leaked back down. It was leaking pretty quickly, about 30-45 seconds from top to bottom. There was a small amount of hydraulic fluid leaking from a little set screw on top of the 3-point casing on the right side. If you were sitting on the seat, it would be right under your right hip. THe oil appeared to be boiling from this set screw (I did not notice a leak from anywhere else - and this one seemed to small to cause this kind of pressure loss). It leaked about 1 or 2 tablespoons of fluid. Since it was boiling, I thought maybe I was low on fluid and it got hot/thin causing me to loose pressure. I let it sit overnight, topped off the hydraulic oil in the 3-point sump, and tried it again. It was still leaking down, but much slower. No fluid leaking out. I used it for about a 1/2 hour and lost the ability to hold up the 3-point up altogether. Now when I raise it up, it lowers almost as fast as it raises. I really don't know how a 3-point works or where to start. Sounds like maybe I've lost a seal or o-ring that is keeping the fluid from holding pressure - but I have no idea where to start or what to look for. I did remove that little set screw on top of the casing, cleaned it, added teflon tape, and replaced it....I knew it was a long shot - and it didn't work. I don't think that leak is the source of my loss of pressure - though I wonder if there is an o-ring inside that has failed and the fluid is making its way to that screw. I just don't know how to find, check, where to start removing....etc. I have been all over the internet looking for schematics of how a 3-point hitch works and can't find much on a Jinma or Tractor King. I don't have an owner's manual. Any help with what my problem is, where to start, and what to do would be much appreciated. Pictures/diagrams would be AWESOME!

One more thing - I found on this site a forum about the pressure control valve and thought "no...it couldn't be that simple" It wasn't. I messed with the needle valve and didn't get any favorable results.

ideas? Thank you for your time and consideration!


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greg_g
Join Date: Jan 2004
Posts: 1816 Western Kentucky
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2011-07-01          179250

There are thumbscrews on the lift lever linkage. My guess is that either they were not set properly, or you forced your way past them when you lifted the boxblade for transport. If/when the rear lift is raised too high, the O-ring and wiper(s) on the lift cylinder are damaged. Permanently.

But to be fair, some folks have had the thumbscrews set correctly - then unknowingly or unwittingly hitting a bump in the road during transport, which in turn raised the implement above the safe lift height. Result is the same, permanent damage to the lift cylinder seals.

By permanent, I mean it will leak permanently unless/until said O-ring and wiper(s) are replaced (some or all of items 15/17/19 on the diagram below)

//greg// ....

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Jinma Farmpro Agracat Nortrac 3-point leaking down
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jnewport2
Join Date: Jul 2011
Posts: 6 Terre Haute, IN
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2011-07-01          179255

That makes total sense. I actually do remember misjudging a bump in the road and hit it pretty hard as I turned onto my road, I heard something - but figured it was just my box bouncing - so I would say this is my culprit! This was less than a minute before my box started dragging. Thank you! So a few questions:

1) Looking at this diagram (thank you for this btw), it looks like I would need to disassemble starting from the front plate. Would I just start with the front plate (14) and work my way in? Does that piston (or whatever you would call 16-19) just slide right out (or is it supposed to)? If so, this doesn't seem all that awful of a job. Is there any advantage to going through the back plate?

2) Where would I purchase the o-rings/rebuild kit and assuming I need to order online, what would I specifically ask for? Would it be as simple as "wipers and o-rings for the lift cylinder of a 3-point of a Tractor King JM200"? I get a little nervous without part numbers to verify with a parts person on the phone what I need - it is more my lack of official terminology. Know of anyplace that specializes in Tractor King parts?

3) Anything else I should know about the disassemble that I should plan for?

Thanks again for your help! ....

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greg_g
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2011-07-02          179256

I've personally never had the need to perform that particular repair. But those who've had reported exactly as you describe; going in through the front. #16 however is the sleeve, I'm not sure that would actually have to come out. The piston is #18. The O-ring on the piston is #15 (metric , the wiper is #19.

What happens when the lift arms are raised too high, is that the piston gets moved partially beyond the lip of the sleeve. That exposes the O-ring and wiper. When the arms are subsequently let back down, the piston is pulled fully back into the sleeve. The O-ring and wiper are damaged as they're forced backwards through the lip. That's why I thought perhaps it might be prudent to have O-ring #17 on hand for the job. That said, the dealer may advise it's not necessary for that kind of mob.

As far as a parts source - any dealer that sells Jinma or any re-badged version of Jinma (FarmPro, NorTrac, etc). But over the years there've been several different lift boxes installed on the 200 Series. Unfortunately, the over-extension problem was never addressed in any of them. Although there was mention of a stop bolt in at least one of them. Anyway. As a result, most dealers will carry what they call a "lift cylinder repair kit". But which kit you need depends upon which box is on your tractor. Some pistons had more than 1 wiper, which is why I used "wiper(s)" earlier. So be prepared to tell the dealer the model year and serial number of your tractor. That info should be on a metal label glued either to the inside of a rear fender or alongside the transmission housing.

//greg// ....

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jnewport2
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2011-07-07          179315

I can't thank you enough for your help. I found a parts dealer online out of TX. They were very friendly on the phone - a smaller operation - which allowed for some real personal service. I asked the parts lady if I could speak to one of their mechanics and he helped walk me through what I would need to do. Between his directions and your picture, I was able to understand what I needed. Below is my experience for future readers:

I ended up taking off the back plate and the front plate. I started with the back to see if I could get to the piston from the back....can't without removing piston rod (27)- but I also wanted to check if I had a stop bolt. The drain plug for the oil located on the back plate and by removing the plate I was able make certain I get all the oil out. I do have a stop bolt - but it was mashed from a few too many hard bumps. It's hard to explain, but basically, the rocker (number 40) that is connected to the piston rod (27? - hard to read) is the part that hits the stop bolt. The connecting point almost straddles the bolt to where the actual contact point is on the outer 1/8" of both sides of the bolt....a few hard jolts and the stop bolt gets mashed out on the edge...allowing for an extra 1/8" of travel for the piston. Which I can attest - is too much.

Moving to the front, I had to remove the top of the gear box (where the shifter is located) in order to remove the front plate. I removed the front plate - it is kind of snug due to the o-ring (The first #15). I ended up using the oil left in the cylinder and pushed down on the 3-point (#30? - hard to read) to help push out the cylinder. It got it most of the way, but still had to work it out by hand a bit. All the oil made a mess....but had to get that oil out anyway. Having the rear plate off turned out to be necessary as I was able to push the piston out of the cylinder(16)with a piece of 1x1 wood. The cylinder is pressed in. Once out the o-ring (15)and neoprene rings (19) were easily replaced.(they were my culprit)

From there I just put it all back together.

The whole thing took less than 3 hours - and that was with my 4-year old "helping".

Pretty painless all-in-all....but next time I need to get the tractor.....I will use the trailer!!! ....

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greg_g
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Posts: 1816 Western Kentucky
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2011-07-07          179317

Great description. Too bad your initiation into the world of Chinese tractors had to be by way of fixing one !! But that's actually one of their attractions; that is, they're basic fix-in-the-field machines.

//greg// ....

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jnewport2
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Posts: 6 Terre Haute, IN
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2011-07-07          179318

You are exactly right. "fix-in-the-field" is what I did and was easy to do. Or at least "fix-in-the-gravel-driveway." Plus the tools necessary are common amateur tinker-er tools. ....

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johna1
Join Date: Aug 2011
Posts: 12 Tasmania,Australia
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2011-08-23          180005

quote
(Moving to the front, I had to remove the top of the gear box (where the shifter is located.)
was there much involved in removing the top of the gear box.Thats where i have to go.
john ....

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greg_g
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2011-08-24          180020

Not at all. Just remove the hex head bolts and lift straight up. But be prepared to cut a new gasket. They usually tear when you lift the cover. And when you get to replacing the cover, just remember to align the lever(s) so that the finger at the bottom fits into the associated sliding fork before you bolt it back down.

//greg// ....

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johna1
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2011-08-24          180031

Thanks for that greg_g.
Buti have found that something elce is wrong with it as i have got the lift working by turning the steering,so the lift must be ok.took it out yesterday and completly lost my steering.This thing is a nightmare. ....

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greg_g
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2011-08-25          180042

Not an unusual problem in the 200 Series. You pretty much described a dirty steering diverter valve. In hydraulic circles it's called the priority valve, or PV. Since the 200 Series usually has only 1 pump, there's only one main hydraulic circuit (loop). The loader is typically slaved off the loop right after the pump. After that, the PV then branches the steering off the loop and into a sub-circuit.

When the PV gets clogged, the hydraulic flow gets "confused". The PV is a Y-shaped cast device, just forward and to the left of your brake pedals. Remove, disassemble, clean, replace

I suspect that when you repaired the rear lift, you left pieces of the damaged seal/wiper behind. That stuff moves with the hydraulic flow, and is likely clogging up various choke points as it circulates. I'd say a thorough hydraulic flush may be in order, or your friend will continue to be plagued with little problems like this.

//greg// ....

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johna1
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2011-08-25          180045

This is my story.
What i have done greg_g ,This is from new i have only had this thing a few weeks direct from china.So i have nobody to complain to.With them i might as well be trying to talk to a monkey.
When i got it i had asked them to attach the FEL and Backhoe before i had it sent.That was my biggest mistake.The fel and the 3pl did not work.When i had it unloaded it had to be draged out of the container.
Now the fel was tee'd into the main output from the pump and had its outlet via a hose to the dipstick hole at the back of the seat So that gave the system two drain points,so if i tryed to use the fel or 3pl all the oil would simply flow via the other return.Fixed that by putting the fel return back into the pv valve.Now the fel works.But still no 3pl.bought a new pv valve because i was thinking it was that, still did not work.found that by turning the steering the 3pl would work.Then the steering packed up.Checked the front steering piston seals and they are ok.The only thing left is the steering box.Now i pulled that apart and i have found a pin and a ball bearing in the inlet of the steering pump just floating around.there is no place for it there,Where they come from i dont know.So my job today is to put the whole thing back together.and try again.I am hoping that it was the ball bearing that has been blocking the inlet hole to the steering pump.I will let you know.
What did suprise me about the steering pump is that the inlet and drain holes are directly coupled with nothing in between them, so the oil for the steering pump is just syphoned off of the hydralic line,i did not expect that.
John ....

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greg_g
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2011-08-27          180066

Ah, I see where I went wrong here. You're not the guy that started this topic. I thought I was still addressing the guy that borrowed a tractor.

So let me regroup here. You mention a steering pump, but most 200 Series have only one pump. That means I have to go back to basics and ask (1) is it in fact a 200 Series Jinma we're talking about here, and (2) is it a one pump or a two pump system? I ask, because I suspect that what you're calling "the steering pump" is actually the steering controller at the bottom of the steering column. A 200 Series single pump system has one engine-driven pump, and uses a PV for steering only. The double pump systems typically have tandem engine-driven pumps, and no PV.

//greg// ....

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johna1
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2011-08-27          180074

Sorry greg_g i seam to have hijacked a thread here.I think i should have started a new one.
steering controller is probably what i meant.I have a europard 304 2 cylinder. it looks like a jimna clone just the same bits.
Only one pump and a pv valve.
Now the latest is the pv valve that i bought was actualy stuck so i freed it up and now that bit works.and i have 3pl working but now i have lost my steering.
If i lift the front wheels off the ground i can turn them but still not easy.There is no power assist to the steering.
when i disconect the pipes to the front steering ram it pumps oil to the right and left sides as it should.took the ram to bits and its all good.its all pointing to the steering controller (pump) now.One other thing if i lift the fel up high and let it down quick it pours out with foam at the back vent.Man this thing is a pain.
john ....

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greg_g
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2011-08-27          180075

Yeah, probably would have been better to start your own. I see now that you've got is a Foton 304. Steering could be the controller, but reported failure rate on that item is pretty low. I'd be more inclined to take a 2nd look at the PV. Because if the steering controller was bad, you wouldn't be getting fluid at the cylinder (ram). When the fronts are off the ground, a good steering controller doesn't even need the engine running to operate the cylinder.

Two things about the loader spewing fluid out the fill/vent; one, don't overfill the sump. Asian dipsticks that are threaded do NOT get threaded back into the hole for a level check. Unscrew, wipe, set back ON hole, remove, check level. And two, always lower the loader (and rear lift) BEFORE you shut off the engine. If you don't, all the cylinder fluid gets pushed by gravity back into the sump. And since the pump's not running, none is taken FROM the sump to fill the other side of the cylinders. Result; sump overflow.

All four of the Chinese tractors I've owned had only a single line on the hydraulic fluid dipstick. I used that line to be the FULL mark. I never added fluid unless/until the stick came out dry.

//greg// ....

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johna1
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2011-08-27          180076

Thanks for that i did not know it was a foton.
The thing with the pv is that if its going its going i only took it off yesterday and it was clear everything is working good.I even replaced it with the old one i had. I found that there was nothing wrong with the old one but did not know untill i checked it against my new one.still the same symptons.
I could not understand how the steering controller actualy works.as i said before in my one there is a direct open conection between the input pipe and the drain pipe.That does not seem right, is that how they are built. it was in this chamber that i found a straight c section cotter pin about 1 and 3/16 inch long and a 5/16 inch ball bearing just floating around and i cound not find anywhere where it came from.
Yes i did that with the dip stick it just seems excessive foaming, after a couple of high lifts i have to refill the hydralics thats how much it spits out.
John ....

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greg_g
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2011-08-28          180078

The technical name for the steering controller is "balance string type hydraulic steering gear", despite the fact that there are no actual gears inside. But there IS a steel check ball in there. Only problem is, I see no way for that ball to "escape" without the controller having been at least partially disassembled at some point. I think you'd be interested in the controller diagram and operating principle, but I have no way to add graphics to this discussion. Given an address however, I could email it to you. The diagram also shows the location of that check ball. Once we start exchanging emails, you could send me a few photos so I can perhaps better understand that "direct open connection" bit.

If you remove the hydraulic vent/fill plug and shine a light inside while the engine is running, can you see bubbles moving? If yes, you've got an air leak on the supply side. If no, it still sounds like the sump is over-full. And again, never drop the loader (or the TPH) when the engine is not running.

//greg// ....

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johna1
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2011-08-28          180080

That would be good then i could understand where the ball goes.I took it to bits again today and put the ball and pin back loose in the chamber where i got it from.Now i have power steering off a sort.The steering wheel only moves about 1 inch from side to side then its a solid stop.If i move it to the right the wheel will power over to the right and same as left but i have hardly any control over it.its very strange but i have definitly narrowed it down to the steering box (pump) the ball bearing must somehow block the drain pipe when i turn the wheel as you can definatly hear the engine load up.my email is jarmson@netspace.net.au
john ....

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greg_g
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2011-08-28          180082

Yeah, when the engine bogs down it's a pretty good indicator that you've got flow restriction and/or a bypass is not working. Email's on the way.

//greg// ....

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jnewport2
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2011-08-28          180086

It is kind of funny...we are both named john. You are in good hands with greg. Man knows his stuff! ....

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johna1
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2011-08-28          180087

Great thanks greg
Now i was on the right track. if you look at the diagram and take the ball out of that chamber you can see that there is a direct open path between the input pipe and output pipe.In the diagram it shows a pin coming out of the end of a bolt.but in mine that pin is just loosly sitting inside the chamber.now i checked all of the bolts hoping to find a hole in the end of one of them that the pin went in but they were all solid. i can drill into the bolt to position the pin but i realy need to know how far the pin protruces.I dont suppose that you have a controler laying around to just pull that one bolt and give me a measure.
Thank you this has been most helpfull.
john
....

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johna1
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2011-08-30          180103

Took the bolt out and drilled 1/4 inch hole in it and installed the pin now its working great, now to work on the air leak.
Thanks greg_g for the drawing and a thanks for tommy at Affordable Tractor Sales for the actual picture of the bolt and measurments.
....

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