JD 990 Hydraulics

   / JD 990 Hydraulics #1  

TXFord8n

Member
Joined
Jun 26, 2011
Messages
28
Tractor
Ford 8n
My JD 990 hydraulics have started to lower much slower than it did when we first bought the machine. It has never had a hydraulic fluid or filter change. Is a plugged filter causing this issue? It raises fine, but lowers slowly with a 600# shredder is on it.
 
   / JD 990 Hydraulics #2  
Since it sounds like it's the 3PH lowering slowly (based upon your comment about the shredder), It's probably the "Rate of Drop" knob turned in a bit.
This knob is located on the panel directly behind your shins (when you're setting in the operator's seat).
Try adjusting that knob first...
Personally, I prefer the 3PH to drop a bit slow...say 2-3 seconds.

If that doesn't help...the next step is to replace your hydraulic fluid, filter and clean out the suction screen. This process will be in the Operator's Manual that came with your 990.
 
   / JD 990 Hydraulics #3  
Like Roy said check the knob first, but by now the tractor should have atleast had a hydraulic filter change. If I remember right judging from the numbering system change, a 990 is at least a couple years old and probably should have had it changed regardless of the hours. Just my 2 cents.
 
   / JD 990 Hydraulics
  • Thread Starter
#4  
It is a six year old tractor, so if that helps recommend a hydraulic change. It is not at the magic hour line yet, but it is close enough. Admittedly, this is a back up tractor as I normally use the 8n for work so I haven't had much use with the adjustment knob. I will give it a go and see what I need to do next.
 

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