Lost hydraulics in JD 7520

spaghetti

New User
Forgive me for lacking knowledge on this however my dad has asked me to try research information on lost hydraulics in his 70's JD 7520. I decided to try here since I can't find much directly online. This is what Im told him or know: since he got the machine hydraulic pressure wasn't always present upon startup......often times he would start the tractor and wait up to a minute for hydraulic pressure.to show....in fact at times the whole machine would jolt and the steering wheel and machine would pivot/move significantly when pressure appeared. Fast forward to a couple weeks ago......he was cultivating when all pressure was lost. No steering, no clutch, nothing to the rear hoses/couldn't lift the cultivator. He's asked mechanics locally but most don't know this machine specifically so now we are in search of an OEM service manual to try find if there is troubleshooting tips or pics of hydraulic system or secondary hydraulic pump info.... anything that could help lead to a solution. Any advice out there?
 
Welcome to the forums.

Go to the John Deere Ag & Turf Bookstore and use the Equipment Publication button. On that page do a model search for 7520. You will get a list of the choices for that model. You may need the serial number as well to pick the right one. There are several Technical Manuals. For troubleshooting you will need the diagnostic one (some times they call them Operation and test). The repair manuals cover the repair wrenching. You should have both. Here is a link to the bookstore.

John Deere Ag & Turf Bookstore
 
Assuming I navigated correctly......and found the preview button for the diagnostic one......am I in the right place when it's saying I can either order booklet.....or CD......or a download.....for a mere $1100-$1300? Not sure that will work for my dad but good to know it's available. Might try find a shop service manual and see if it talks hydraulics
 
TM 1053 is the manual you need. Looks like Jensales has them for about $84

(for some reason I can't get the link to work)
 
Forgive me for lacking knowledge on this however my dad has asked me to try research information on lost hydraulics in his 70's JD 7520. I decided to try here since I can't find much directly online. This is what Im told him or know: since he got the machine hydraulic pressure wasn't always present upon startup......often times he would start the tractor and wait up to a minute for hydraulic pressure.to show....in fact at times the whole machine would jolt and the steering wheel and machine would pivot/move significantly when pressure appeared. Fast forward to a couple weeks ago......he was cultivating when all pressure was lost. No steering, no clutch, nothing to the rear hoses/couldn't lift the cultivator. He's asked mechanics locally but most don't know this machine specifically so now we are in search of an OEM service manual to try find if there is troubleshooting tips or pics of hydraulic system or secondary hydraulic pump info.... anything that could help lead to a solution. Any advice out there?
Your '70's 7520 doesn't have a hydraulic clutch or "two speed" so hydraulic failure won't stop it from moving/driving.

With the engine running, is the upper shaft in the hinge area turning? IF not something a has failed in the engine clutch area.

And without the upper shaft turning the transmission pump is not operating and supplying oil to the main hydraulic pump up front, so there will be NO steering or brakes or flow to the remote valves.

GUESS these othe fellows aren't familiar with your CLASSIC green tractor?
 
Thank you all for input. Much appreciated. Will take a look at that upper shaft. My understanding is he can't get the clutch to engage and has lost steering etc......his assumption has been clutch failure but we weren't sure if hydraulic failure is causing all the issues. Will see about that upper shaft. Also will check out that TM 1053 manual. I saw that today on a couple different searches.
 
I reached out to my dad and he recalls the last time they tried anything a few days ago the upper shaft was turning and he said they could hear the hydraulic pump making some noise. He did say the day everything failed there was a very loud howl noise and the machine stopped so he immediately tried to hit the clutch but it was solid so he had to jam the tractor out of gear. The loud howl noise was still happening so he shut it down. Next day they got the cultivator disconnected and when they started the tractor the noise was gone but the clutch was still solid.....won't move. And with tractor running..... there was no steering or hydraulic to the rear and no way to get clutch pushed in. He did say one old timer from a shop sold that tractor has a wet clutch........but then said another mechanic said it's a dry clutch. So we don't know for sure. Gonna try get a service manual for some answers.
 
Assuming I navigated correctly......and found the preview button for the diagnostic one......am I in the right place when it's saying I can either order booklet.....or CD......or a download.....for a mere $1100-$1300? Not sure that will work for my dad but good to know it's available. Might try find a shop service manual and see if it talks hydraulics
That is the right place. Technical Manual is the name John Deere uses for their "shop/service" manuals now.

TM1053 appears to be the right manual for the 70's articulated 7520. It is about $60 from John Deere. The Diagnostic manuals are for the newer non-articulated 7520s. And yes, many of the new manuals are expensive, that's why one needs to be sure they are ordering the right ones.
 
Your '70's 7520 doesn't have a hydraulic clutch or "two speed" so hydraulic failure won't stop it from moving/driving.

With the engine running, is the upper shaft in the hinge area turning? IF not something a has failed in the engine clutch area.

And without the upper shaft turning the transmission pump is not operating and supplying oil to the main hydraulic pump up front, so there will be NO steering or brakes or flow to the remote valves.

GUESS these othe fellows aren't familiar with your CLASSIC green tractor?
I admit I am not familiar with his CLASSIC green tractor. I did not research models changes over the years or serial numbers. I only tried to give him info on finding the correct OEM manuals for the 7520s.
 
TM 1053 is the manual you need. Looks like Jensales has them for about $84

(for some reason I can't get the link to work)
Your link is likely blocked by the site software as Jensales is a competitor to PartsASAP/YT. Direct links to those seen as competitors were often blocked by the old software and still seem to be with the new software.
 
I agree with wore out in that it sounds as if input shaft of transmission has lost it's power supply which also stops trans pump from supplying oil to front hyd pump.
 
So if the shaft is spinning and some sound is present at the hydraulic pump what causes there to be no steering or rear hydraulics at all?...plugged system? And on top of that if it's a dry is the clutch a whole separate issue and went out completely on its own since it's solid? I wouldn't think the clutch going out would cause a hydraulic problem. Or does something with that shaft assist the clutch somehow....and the loud howling noise was the initial evidence that something was going out that is detrimental to both clutch and hydraulics Beside the rear transmission pump.....and hydraulic pump up front.......is there another assisting pump somewhere that could've gone out and made that sound? They're changing hydraulic filter today to see if something could be blocking hydraulic pump since it sounds like it's trying to work. Dad's old school and wants a book to look at so gonna try get a tm manual soon.
Thanks again for all the input. Much appreciated
 

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