# john deere 1520



## petefarms (Oct 17, 2004)

hydraulic problem, i'm told the tractor has to run for approx one hour for the hydraulic loader to raise and lower. was told the hydraulic fluid is ok, plugged filter, pump, not my tractor but am going to try to help repair so it will run and plow snow. it is a gas tractor. thanks.


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## farminghandyman (Mar 4, 2005)

check the pump drive off the front of the engine, 
I have a 4020 but the pump drive splines wore away and was not turning the pump, 
could not feel or hear any thing out of the ordinary, my tractor has about 9600 hrs,

not real familiar with the smaller JD tractors of that era, but 

it appears to be be a closed center hydraulics,
if the filter has not been replaced in a long time replace, and change oil if it has not been changed any time lately, should be changed annually by manual, but if it been over 5 years change,
Did it stop all at once or slowly over time? (fast more than likely failure of some component) slowly check or replace the filter,

Go to http://jdparts.deere.com/ and sign in and you can look up the tractor on parts, 

the charge pump is under the heading of "transmission clutch oil manifold",

and the main pump is under "hydraulic pump" IF i ma remembering correctly,

If you can stop by a dealer and look and copy off the pages of the service manual it may help you out a lot, 

but my experience has been you need a flow meter and some hydraulic diagnostic tools, to use effectively, but understanding the flow diagram is help full,

I did or was able to put a pressure gage on the fitting coming out of the transmission up to the main pump and found out the transmission pump was pumping , it was by passing through the main pump as it was no turning on my tractor and the pressure was low, but did find out it was pumping, 

Did read one other trick if you need to work under the tractor and pulling off lines and checking out any valves or relief valves, and oil leaking out, is to put a shop vacuum on the fill port and turn on and as you take off the lines or fittings it will pull air in the fitting area and keep the oil from running out of the open ports, (no I did not read this trick until I was done trouble shooting my tractor, and thus did not try the idea out but it does make sense to me)

are other hydraulics working before the warm up time, or does it just take the loader that long


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## oneokie (Aug 14, 2009)

Not sure if it applies to the 1520, look on the left side of the rear axle housing in front of the lift arm shaft. If there is a plug with a square recess, there is a screen behind the plug. You will need to drain the fluid before removing the plug and screen. A pair of needle nose pliers are handy in removing the screen. 

If the tractor has power steering, does it operate? How fast do the 3pt. lift arms raise?


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## agmantoo (May 23, 2003)

Not much to go on but here are my thoughts. The pump is working when the tractor is hot. Usually pumps that are worn are just the opposite and work best when cold so I would guess the pump is OK. When the tractor finally heats up, the oil is hot and it flows more readily so I would think that something is restricting the flow. Anytime I have a hydraulic problem, I check for the reservoir being filled correctly and with the correct oil then I look for a something clogged and change the filter. If the filter replacement does not fix the problem, I then look for a screen or a blocked orifice. I do not know what is limiting the amount of oil to the lift but IMO whatever it is, it is not the pump and if it were a bypass/relief valve with a broken spring the lift would not work once the oil heats.


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## Old Vet (Oct 15, 2006)

petefarms said:


> hydraulic problem, i'm told the tractor has to run for approx one hour for the hydraulic loader to raise and lower. was told the hydraulic fluid is ok, plugged filter, pump, not my tractor but am going to try to help repair so it will run and plow snow. it is a gas tractor. thanks.



I think that somebody is pulling your chain. In all John Deers the hydrolic pumps work from the time they start. Check your hudrolic filter and change it. That will usualy solve the problem.


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## T-Bone 369 (Jan 18, 2007)

One many moons ago I had a similar problem with my IH 300 Utility - real slow hyds until the tractor ran for a few minutes. Everything looked good line wise, changed the oil, ect but nothing worked. Turned out that the low pressure hose going to the pump had seperated and the inter lining was obstructing the flow to the pump. After a bit the bulge would get pushed in (heat in the oil or back pressure I never could figure out why). Swapped it out and worked like a champ. Was a real bear to diagnose - had removed it to look at removing the pump and accidently stuck a finger inside and realized it was squishy.


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