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JD 3520 eHydro 4x4 hydraulis problems

bdblount723 Join Date: Mar 2009 Posts: 8 Louisiana

2009-03-02          160722

I am having problems with the hydraulics on my 3520. The 300CX loader operates very jumpy and makes a lot of hissing sounds when raising and lowering. In addition, the 3 point lift will jump when an attachment is completely raised up. It will start to slowly lower a couple inches then suddenly you can hear hydraulic fluid rush to it and it will bump back up. It usually makes a hissing sound when this happens. Can anyone suggest anything to check? All filters and hydrulic fluid was changed recently with JD parts and lo vis oil.

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JD 3520 eHydro 4x4 hydraulis problems

kwschumm Join Date: Feb 2003 Posts: 5764 NW Oregon   Pics

2009-03-02          160723

Fluid low or sucking air somewhere? ....

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JD 3520 eHydro 4x4 hydraulis problems

bdblount723 Join Date: Mar 2009 Posts: 8 Louisiana

2009-03-02          160731

The fluid level is in the top 2/3 of dipstick when cold and all attachments lowered. Could it be an inline filter anywhere in system that is clogged? ....

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JD 3520 eHydro 4x4 hydraulis problems

kwschumm Join Date: Feb 2003 Posts: 5764 NW Oregon   Pics

2009-03-02          160732

Did this problem start happening right after the fluid was changed? Sometimes if you get air in the system it just has to work it's way out through use.
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JD 3520 eHydro 4x4 hydraulis problems

bdblount723 Join Date: Mar 2009 Posts: 8 Louisiana

2009-03-02          160733

The problem was the same before I changed the oil and filter. I can't help but think the hydraulic pump is going out. At times the tractor performs well with lots of power. It gradually worsens as the machine heats up under load. I used to have a JD 4200 with FEL and it did the same darn thing. That was pretty much the only reason I sold it and got the 3520. ....

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JD 3520 eHydro 4x4 hydraulis problems

kwschumm Join Date: Feb 2003 Posts: 5764 NW Oregon   Pics

2009-03-02          160734

I'm no expert in this regard, but if it were my tractor I'd start out this way. First, relieve all pressure in the hydraulic system and then disconnect all four hoses going to the loader at the quick disconnects. Then start the tractor and operate the 3ph a few times. Does it still jump around? If no, then the problem is somewhere in the loader circuit.
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JD 3520 eHydro 4x4 hydraulis problems

Murf Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada   Pics

2009-03-02          160735

There is only two things that I've seen cause symptoms like that were a) cavitation caused by air trapped in the system, or b) a problem with the relief valve.

The first one, cavitation, is IMHO most likely and luckily the easiest to cure.

The relief valve is easy to diagnose, just temporarily install a pressure gauge in the system, call for pressure and watch the gauge, but usually hard (and spendy) to replace.

Best of luck. ....

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JD 3520 eHydro 4x4 hydraulis problems

earthwrks Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan   Pics

2009-03-02          160736

I'm leaning torwad a bad pump too since the problem gets worse when the oil gets hotter--the pump is expanding on an already marginal pump allowing fluid to slip past the pump gears.

To test this theory, the next time it is acting up, get the oil really warm then run cold water from a hose over the pump and the oil cooler for about 10 minutes and see if it gets better.

Yup this one got away from me before I spellchecked it---actually Kenny typed it :) ....

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JD 3520 eHydro 4x4 hydraulis problems

Murf Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada   Pics

2009-03-02          160738

Quote: Originally Posted by bdblount723 | view 160733

[QUOTE=bdblount723;160733] The problem was the same before I changed the oil and filter.

At times the tractor performs well with lots of power. [/QUOTE]

Those two sentences lead me away from the bad pump idea.

First off, bad pumps usually perform worse under pressure, pardon the pun, than not, cold oil is thicker, creating better pressure, as the oil warms it thins, making the pump work easier.

Secondly, if the pump was going out, there would be LOTS of debris in the oil when it was changed. The OP makes no comment about the oil being anything but changed. I would think if it was really bad he would have said so.

Either way, a $20 gauge on a QD fitting will tell volumes about the problem.

Best of luck. ....

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JD 3520 eHydro 4x4 hydraulis problems

earthwrks Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan   Pics

2009-03-02          160743

Murf maybe I read the the whole thread wrong--- but it sounds like because he had the problem, to remedy it he changed the oil to no avail. ....

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JD 3520 eHydro 4x4 hydraulis problems

Murf Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada   Pics

2009-03-03          160749

Quote: Originally Posted by earthwrks | view 160743 Murf maybe I read the the whole thread wrong--- but it sounds like because he had the problem, to remedy it he changed the oil to no avail.

I completely agree, but if the oil didn't look right I'm sure the OP would have said so.

I've never seen a pump go out and the oil stayed clean. There is always a bunch of crud in it by then. It usually smells bad too, like burnt transmission fluid does.

Best of luck. ....

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JD 3520 eHydro 4x4 hydraulis problems

hardwood Join Date: Dec 2002 Posts: 3583 iowa

2009-03-03          160754

The part about the three point lowering then suddenly going back up makes me think of a control valve problem. I don't know what valve but perhaps a relief valve sticking then snapping shut??? ....

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JD 3520 eHydro 4x4 hydraulis problems

bdblount723 Join Date: Mar 2009 Posts: 8 Louisiana

2009-03-03          160760

I'm just catching up on the thread because I haven't had access to computer today until now. The oil was relatively clean when it was changed (no metal filings). I think it has to be the relief valve or vanes or gears in the hydraulic pump. Do any of you know where the relief valve is located? ....

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JD 3520 eHydro 4x4 hydraulis problems

Murf Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada   Pics

2009-03-03          160761

Quote: Originally Posted by bdblount723 | view 160760 The oil was relatively clean when it was changed (no metal filings). I think it has to be the relief valve or vanes or gears in the hydraulic pump.

Again, IMHO, if it was the pump you would have found debris when you changed the oil. When things like that break they tend to get really chewed up leaving lots of little bits, they don't just break in half.

I don't know much about JD machines, but I'm sure one of the folks here who does will chime in soon.

Best of luck. ....

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JD 3520 eHydro 4x4 hydraulis problems

earthwrks Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan   Pics

2009-03-03          160768

Murf in all the equipment I have had pumps fail, which was usually due to running low on fluid, there was not any hot-smelling oil, or such. There was however glittery particles in the oil from the pressure plates wearing on the pump gears.

I'd be surprised if you had a vane pump. ....

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