John Deere 2720 - Zero Hydraulics, Zero 3-Point Hitch, Zero Answers...

[smashedtoe]

Hello all.

First, my apologies if I am posting this in the incorrect location.

I have a John Deere 2720 with 419 hours. Approximately 3 months ago i noticed the hydraulics (loader, snow blower) and 3-point hitch were moving much slower than usual so I did what every other newbie would do, spend $270 on JD filter and Hy-guard oil, changed the filter, cleaned the suction screen (which was very clean to begin with) and......nothing. No difference.

Last week, out of desperation, I tossed another $270 away and did the same thing, thinking that maybe the tractor fairy was asleep the first time and changed oil, the filter and checked the suction screen - all good in the hood. Just like that presto! Everything was working like new. I did a little dance, squealed like a teen asked to prom and away I went. Wind was blowing through my hair as I was mowing the lawn, everything was working super and I was happy. I set my son up to pull fence posts out with the 3-point hitch attachment and promised him $5 for every post he removed. Hey, if food will get him off the video games, maybe an incentive for money would too. He pulled about 20 posts and then informed me the tractor doesnt want to lift them any more.

When I return home for the weekend from work, I started up the 2720 and noticed the hydraulics were moving very slow again with no lifting power. I figured I would take my chances once again, change the filter, the oil and check the screen (seemed to work last time and apparently I love to waste money). This time, to my amazement, I had NOTHING! Zero hydraulic function and the 3-point hitch hung lower than my head.

I have zero pressure at any of the quick couplers, no indication of effort when raising the rockshaft lever and the hydraulic oil level does not lower from the site glass when the tractor is running, regardless of engine speed.

If anyone can offer any suggestion, help, guidance or at this point in time some old fashion ridiculing as I am desperate.

Helpless in Manitoba

 

[Storm56]

You need to start looking at the hydraulic pump which should be attached to the engine. I have never had one apart so no help there. Pull it and look for something obvious like a broken shaft etc. They can be rebuilt if it is an internal problem. Good luck in your delema.

 

[KennyG]

Unless you have a lot of tools and experience, this is probably an issue for the dealer and it will be expensive. My first guess would be a failure of the pressure relief valve in the hydraulic system, because a broken pump wouldn't come and go.

 

[Storm56]

Kenny you are likely correct that this is a job for a professional. On the bypass thing, had that issue once. You would hear a whining sound while it was in bypass and it heated the fluid up pretty fast.

 

[Roadworthy]

At the risk of questioning the obvious, you don't have the three point lever hard against the "up" do you? Something that simple can cause your symptoms. I won't go into the definition of insanity.

 

[smashedtoe]

Thanks to all for responding. All hydraulics (less the hydrostatic drive) have quit working all together and I do not seem to have any pressure in the system whatsoever. Is there anything I can test/check to see if the pump itself is working? I loosened off a couple lines with the tractor running and no sign of oil at any of the joints. Any help would be appreciated.

 

[oldnslo]

Do you still have power steering or did it stop also? Looking at JD parts diagram I think the power steering is separate pump from implements.

Which lines did you loosen? Line from pump to valve stack is the pressure line. This should leak with tractor running. I would suggest opening this line with tractor off and then turn engine over and watch for oil if tractor starts it should pump a good stream at idle so do not run it very long.

It would be rare for hydraulic pump to work, quit, work , quit but possible. Again looking at parts breakdown I think the implement pump feeds the directional control valve loader valve) assembly and then that powers the 3 point.
Relief valve is most likely located in this valve but I could not find any exploded views of the valve assembly.

Do you have capability of installing pressure gauge?

Can be as simple as plugged into one of the loader quick disconnects.

 

[Zebrafive]

Do you still have power steering or did it stop also? Looking at JD parts diagram I think the power steering is separate pump from implements.

Which lines did you loosen? Line from pump to valve stack is the pressure line. This should leak with tractor running. I would suggest opening this line with tractor off and then turn engine over and watch for oil if tractor starts it should pump a good stream at idle so do not run it very long.

It would be rare for hydraulic pump to work, quit, work , quit but possible. Again looking at parts breakdown I think the implement pump feeds the directional control valve loader valve) assembly and then that powers the 3 point.
Relief valve is most likely located in this valve but I could not find any exploded views of the valve assembly.

Do you have capability of installing pressure gauge?

Can be as simple as plugged into one of the loader quick disconnects.

I think you are correct, two pumps, one for PS and one for implements.

Drawings are Implement pump, both pumps, lines to implement pump.
Check the elbow, highlighted in yellow, for collapsing.
Steel line from implement pump is one that will be output.

 

[smashedtoe]

Well folks I finally found the problem! There is a seal inside the hydraulic pump (back side) which was blown.
It is the one which wraps around the two shaft ends (if that makes any sense) and prevents the hydraulic oil from diverting from the inlet/outlet portion of the pump.

 

[DK35vince]

Thanks for the update.
Might help someone out if they have a similar issue some day.
Glad you found the problem.