# JD 850 hydraulic questions



## solargh (Apr 28, 2017)

As the new owner of a seemingly well maintained JD 850 2WD (79) I'm hoping there are a few owners that might answer a question or two. My son bought it for me in Phoenix and brought it to me on the mountain so didn't get to speak with the PO.
The tractor has a front bucket and of course a three point set up. On starting the hydraulics won't move anything for at least 5 minutes and at best at a sloth's pace when asking it to lift either. Down is no issue once it finally warms up though.
The previous owner had a service done last September (date on the oil filter) and the hydraulic fluid is correct and clean on the dip stick. the hydraulic spin on is clean but can't tell if the screen was cleaned.
I see that JD uses a "low viscosity" fluid. Is there an issue when using other than JD brand ?
Any other suggestions would be appreciated.
Thanks


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## Fedup (Feb 25, 2014)

Fluid brand should not be an issue. Viscosity shouldn't be much of a factor either, unless you have a partially(or more) restricted suction screen or filter, or your ambient temperature is much below freezing. 
The hydraulic piping on the 850 varies somewhat based on tractor serial number, but every one I've seen has a screen in the bottom of the tractor through which oil must pass before reaching the pump. At this point I would suggest you drain your fluid, remove and clean that screen, and see what that gains you. A bit messy, yes, but it doesn't cost much and then you have a starting point for future troubleshooting.


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## solargh (Apr 28, 2017)

*Thanks*

That's on my list to do as soon as I get a clean container to store the fluid in. All hoses are recently replaced by the previous owner so may be interesting to see what the screen caught. Still around freezing in the morning but I don't play with the tractor till midday. We have a JD guru close by with at least 20 restored tractors and I would like to hear his experienced views as well when I can get hold of him.


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## solargh (Apr 28, 2017)

*viscosity*

Had a chance to drain the fluid Wednesday and check the screen which was clean. As an experiment I replaced 2 gallons of older fluid with new low viscosity and then filled with remaining fluid to correct mark on the stick. It improved the quickness somewhat but not great and still took a few minutes to start working the next morning at about 45 degrees. I didn't get a chance to try today until later but at 80 degrees this afternoon I did start it up. It performed well immediately with no time lag for warm up needed but has a slight hiccup as it lifts.
I ordered a new spin on today and as soon as it arrives I will replace the fluid with 10 or 15 weight fluid . Maybe there is a reason JD sells low viscosity hydraulic fluid?


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## solargh (Apr 28, 2017)

*viscosity*

I changed the hydraulic oil and filter and put in 10 weight fluid from NAPA. 19 quarts must be for basic tranny and hydraulic fluid needs and had to add more because of the FEL needs. The hydraulics now work perfectly and as rapid as I think they should.
Either the spin on was partially plugged and/or the fluid was too thick for the screen to handle.


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