John Deere 4000 Hydraulic Issue

paJD4000 · Jul 18, 2017

Was using my 4000 to mow hay last weekend and when I went to pick the haybine up at the end
of the field, I had no hydraulics. I still had good steering and good brakes. I took the
tractor to my shop. Pulled the transmission screen it was clean. Replaced the hydraulic
filter still no change. Checked the pressure adjustment spring in the main hydraulic pump
and no issues there. I put a pressure gauge on the rear remote. I was told it should read
anywhere from 2100-2250. I got 1500psi. When i revved the tractors the pressure would
bounce between 1400-1600psi. Does this sound like the main hydraulic pump is bad or could
it be something different?

tim s · Jul 18, 2017

It could be a sticky stroke control valve , but a lot of times the spring that puts tension on the stroke valve gets a bit weak from use in the hot oil, this will let the pressure drop over time and you won't really notice it till it drops below the 1700psi thresh hold, at that point the priority valve shuts off the oil going to the hitch and SCV's,and still gives enough to make the steering and brakes work, it's a safety feature. Try to screw the stroke valve adjusting screw "in" and see if the pressure raises.

buickanddeere · Jul 18, 2017

I am trying to remember something about an unusual case one time where the priority valve was sticking , worn or something and limited flow or pressure to the SCV ? Of course it was on a Dubuque/Mannheim.

ET · Jul 18, 2017

You have a piece of junk not letting your stroke control valve seat properly. Get a manual de-stroking screw from your dealer and install it in the pump. De-stroke the pump with the tractor running and it should push the particle of junk out of the valve. Back off the de-stroking screw and you are good to go.

John Deere 4000 Hydraulic Issue

paJD4000

New User

tim s

Well-known Member

buickanddeere

Well-known Member

ET

Well-known Member

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