JD 7520 hydraulics

[rrperformance]

I"m troubleshooting the hydraulic system on a 7520. It seems to pressurize the return linethat runs from the outlet manifold (@ back of cab) to the rear end. It will actually blow that line apart after running a few minutes. Any ideas are greatly appreciated!

 

[rexhellwig]

Are we talkin' the old full size 4WD 7520 or the less than ten year old 7520 utility type tractor?

Any optional hydraulics the tractor is equipped with ?

A picture or two would be worth a thousand words.

 

[Tx Jim]

(quoted from post at 14:37:17 12/24/11) Are we talkin' the old full size 4WD 7520 or the less than ten year old 7520 utility type tractor?

I would think a 125 pto HP tractor built between '03 & '07 would be classified larger than a utility tractor.

 

[rrperformance]

Sorry.....
This is the old articulated 7520, so the hydraulics control steering, brakes, three remotes, and rockshaft.

 

[rexhellwig]

OK

Tell us then how you would classify a plastic and pot-metal multipurpose tractor.

While you're at it, go ahead and answer the gentleman's question. I'm sure you'll have no problem doing so.

 

[buickanddeere]

That's a low pressure line intended to return oil to either the trans sump. Or to a port between the trans pump outlet and the trans filter. Now certain on those tractors.
The trans pump charge pressure maybe too high?
Is there anything connected to the scv's when the when this blow-out occurs?
Is there any leakage past any of the scv connectors when at the "closed" position ?

 

[Tx Jim]

(quoted from post at 18:17:01 12/24/11) OK

Tell us then how you would classify a plastic and pot-metal multipurpose tractor.

While you're at it, go ahead and answer the gentleman's question. I'm sure you'll have no problem doing so.

JD classified the '03-'07 7520 as a rowcrop not utility tractor.

 

[Tx Jim]

(quoted from post at 15:54:32 12/24/11) Sorry.....
This is the old articulated 7520, so the hydraulics control steering, brakes, three remotes, and rockshaft.

I would recommend checking stand-by pressure which should be around 2250 psi. If it is the line I looked up in the parts catalog I'd think the return port must have a restriction. The line I'm referring to attaches to filter relief valve housing(part # AR52630) on LH side of the trans case. Possible faulty hyd filter relief valve.

 

[7520619]

I am having similar problem with my 7520. I have blown the same hose a couple times but it is usually every 2-300 hours. I know there is an internal leak somewhere because the oil gets exremely hot (have to change the hydraulic every 100 hrs or it wont even steer. The only lines that show hot for testing are the input line and the line that returns to the rear. You can feel the line is flowing at full capacity and im pretty sure it is only supposed to be a small amount. I have asked about 20 different jd mechanics and they all say the same thing...you have an internal leak! Its getting really frustrating as the tractor runs perfectly every other way. Its backflowing so much that I cant even run a hydraulic auger or my airseeder that only requires 10gpm. The SCV lines dont get warm under testing, just after the whole system gets warmed up. If you find out let me know...Im pretty sure we fighting the same battle.

 

[Tx Jim]

7520619
If you want to repair your tractor a flow meter & JD tech manual would be wise investments.

 

[buickanddeere]

Should be zero flow on the HP lines and return lines unless a scv, rockshaft or PS is operated.it's a closed center system.