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  1. #1

    Default jinma hydraulics

    I have a jinma 284. I replaced the diverter valve and the hydraulic pump because something was killing the engine when I tried to use the front loader. I tried to use the front end loader after replacing both the diverter valve and the pump and the housing of the new pump cracked wide open. I have no idea where to start to diagnos the problem. Any help would be greatly appreciated. Doug

  2. #2
    Super Member ronjhall's Avatar
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    Default Re: jinma hydraulics

    I'm not familiar with a Jinma 284. But I would suspect that the relief valve in the Loader valve or the tractor is set to high.

  3. #3
    Epic Contributor Soundguy's Avatar
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    Default Re: jinma hydraulics

    Lets look at physics here for a few minutes, instead of just swapping parts only to see them die a few seconds later. Action and reaction ... the pump died as a reaction. ( to it's action ).. to make a reference to an old joke.. pump went 'umph!'.. blockage went 'umph!' pump housing went 'pop!'...

    Your pump is pumping.. it is a positive displacement setup. if the output is blocked, the oil has to go somewhere.. and the case and seals are the weak links. Ideally there would be a relief in the system, right after the pump. before any other taps.. etc.. but the chinese didn't do it that way. My guess is they are making a decent living on selling tractors with qd's after the pump and no relief before the qd..e tc.

    Anyway.. from looking back at the vast number of 'my loader deosn't work and my pump is dead and my tractor stalls' posts.. they are mostly having problems with quick disconnects that are not really connected.. thus not passing oil.. thus creating back pressure at the pump.. thus cracking the pump.. etc.

    good luck.. and do a few diagnostics before you change those parts... will save you some $$ next time.

    Soundguy

  4. #4
    Elite Member RonMar's Avatar
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    Jinma 284 delivered 06/28/05

    Default Re: jinma hydraulics

    Well if it was running fine untill you try to use the loader by moveing one of the loader valve controls, I would say that there could be something wrong with the loader valve. If the loader valve is operating properly, it should have a safety that will allow fluid from the pump to bypass an overloaded condition. This bypass is usually right at the input port on the valve. At any rate, a properly functioning valve would remove an overload or blocked condition as soon as the handle was returned to the neutral position. This sounds like two problems with a single component. Not impossible but highly unlikly.

    What could be happening is that the changing of the flow through the system when you work a loader control is causing one of the quick connect fittings to "lock up" and stop the flow through the system completely. This could really be a possibility with missmatched quick connectors such as mateing the jinma connectors to connectors made by someone else. You can remove the quick connects from the system entirely and hard plumb the loader valve into the system, or you can unscrew the quick connects off the hoses and from the back side remove the snap ring, spring plate, spring and ball from all 4 of the quick connect components(2 male, 2 female fittings) then re-attach them to their lines and connect them up. This still allows you to easilly remove the loader(engine turned off of course), you will just leak a little oil from the open QC's each time you need to do so. If I recall correctly there was just recently a problem like this on this forum and the person elected to remove the balls and springs from the quick connects and all was fine after that.

  5. #5
    Super Star Member Egon's Avatar
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    Default Re: jinma hydraulics


    Are the hydrauilic lines hooked up properly. [ right lines to the right ports]

    Egon

  6. #6
    Gold Member Harrygoodwrench's Avatar
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    Default Re: jinma hydraulics

    Ronmar, I agree with you and think you are right on track. there have been a few that had this problem. This was discussed just recently here and I gave the reason but I'll do it again as its important.
    The China QD's are pin type. they work fine when coupled with another pin type. Problem is, many FEL couplers use ball type. I know this for fact as when I bought my tractor (Jinma 224) and later bought my Koyker FEL thats what they had. Sometimes mating together unlike QD's restrict or block flow and there goes pump.
    I went out and bought two ball type Pioneer QD's and replaced the China pin type QD's. Now there is no possible restriction unless I do something stupid like disconnect FEL and not reconnect the tractor lines. I still use the zip tie insurance.
    You could just remove one existing China QD from one line and replace it with a ball type, do same to other line, and all should be good as they will be same type mating UNLESS you decide to disconnect FEL. Then you would have same possible problem.
    For the exra 20 bucks for the same type QD's I think thats the way to go.

    Warning. NEVER run engine with QD's unhooked.

  7. #7
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    Default Re: jinma hydraulics

    SoundGuy,

    It would be nice to have presure relief just after the pump. I agree, I seen way to many sad storys like this. How much does a pump cost? vs some relief?

    Patrick

  8. #8
    Epic Contributor Soundguy's Avatar
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    Default Re: jinma hydraulics

    Heck.. even if the pump cost more than the relief setup.. it would be worth it in my book as insurance for that one time you are out int he field and the pump goes south due to a forgetfull moment or bad downstream component.. that is.. it saves you the downtime of getting and installing the new pump. Even if you kept a new pump on hand.. depending on where you are.. it could kill a days work doing the swap.. vs having the extra 1-time expense of installing a relief valve right at the pump.. etc.. that and a return line.. etc..

    Soundguy

  9. #9
    Veteran Member bluechip's Avatar
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    Default Re: jinma hydraulics

    Ouch,
    Open center system so the oil must flow freely from tank to pump to tank, only has pressure when under load. Originally designed to flow from pump back to lift box (which contains pressure releif valve) Then most likely an early importer suggested some quick connects between the pump and lift box for easy loader installation. This works fine PROVIDED none of the quick connects are loose or become loose during operation (tie wrap them to prevent accidental release) they have check valves in them that will stop the flow, (the intent that your oil does not run out and the cylinders collapse when you unhook). These check valves will block the flow of oil ahead of teh pressure relief valve in the lift valve. SO the most likely culprit is a bad or loose quick connect as has already been posted. The best thing it to check the quick connects, remove them from the hoses and look for trash on the back side of the valve, etc.

    So I am taking up a lot of space to add that you can eliminate the loader and see if if it is the loader valve by taking the quick connect off the pump and attaching it directly to the one on the steering priority vavle which you have already replaced. If the 3 point works and the engine does not stall or blow up your pump than you have a loader valve problem and you can repair/replace. Always do this testing at low idle as the engine will usually stall before cracking a pump. (you may blow the seal anyway which is why I say take the connectors off and check carefully).

    Has your tractor worked OK in the past or are you just getting it together? It is always best to test run the tractor/lift box before adding a loader so you add variables one at a time. Fortunately the pumps are relatively inexpensive, around $100.

  10. #10
    Platinum Member
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    Default Re: jinma hydraulics

    SoundGuy,

    I'm voting for the protection of a relief valve. Have you seen this as an add on?

    Patrick

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