John Deere Hydraulic problems.

T. Quinlan

New User
Hope someone can help with this problem,I have a 540B John Deere log skidder thats lost all hydraulics. It has a powershift trans,the machine set for 2 years before I bought it and rebuilt the engine,it moves ahead and back with no problem,if it sits overnight the hydraulics will work in the morning for about a minute or 2,then quits.I changed the hyd. filters,trans filter and cleaned the sump screen which wasn't dirty.I checked the supply oil to the main hyd. pump from the trans,I get a gallon or 2 and then it stops with just a slight trickle occasionally after that.Checked trans pump pressure,I got over 175 psi at 2200 rpm. I don't know what else to try,anyone got any ideas?
 
Sounds like the pump might be sucking air. The pump fills with oil overnight but when it runs out of oil it looses its prime. Maybe RW
 
its possible that one of the hoses has colapsed internally. it could have some pieces of it that flop down when fluid starts trying to run through the hose and acts like a dam. take one hose a off at a time or lossen them one at a time until you find which one stops the flow. first remove a line on the out bound side of the pump as close to it as you can get and go from there.
 
Check the filter bypass valve if it is bad it will dump charge oil back to sump. you should have a min. of 5 psi charge pressure at the pump. I am not sure about the spec but you should have about 5 gal a minute of oil all the time suppling the pump. that 175 psi you got is the powershift trans oil pressure. If you can't find the filter bypass valve let me know I will look it up.
Good Luck Ed
abcrepairparts
 
I took the filter by-pass valve out and the only thing I can see wrong is that the spring is a little shorter than the tec manual says it should be,what should I do next?
 
Hey I just looked at the book and the oil cooler relief valve dumps to sump as well as the filter by pass. I don't think you have a pump problem you have a leak somewhere.
good Luck Ed
 

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