JD 4300 weak front end loader

   / JD 4300 weak front end loader
  • Thread Starter
#21  
Still trying to trouble shoot this issue. I removed, inspected, cleaned and reinstalled the pressure relief valve. It looked perfect. No change in behavior.

I知 not sure if the behavior and / or 都ound is telling me what the problem is but I took a quick video and will describe the behavior and see if that helps.

When I barely pull back the stick there is a 塗issing sound that is coming from under the seat. It doesn稚 sound like it痴 coming from the FEL control but rather more towards the middle left side of the seat. Hard to pinpoint. The hissing obviously sounds like fluid passing a narrow place. As I pull back more the hissing will eventually stop about the time the loader will start to raise. Letting back off of the stick produces the same results in reverse.

Here is a link to the video that I posted.

September 10, 2019 - YouTube

This may not help at all but I thought it might be worth a shot.

When the tractor is turned off with the loader raised it will hold up pretty well. No fast leak at all. Several minutes to leak down which is the ways it痴 always done.
 
   / JD 4300 weak front end loader #22  
Sure looks like a cylinder.......much like the video I posted above.
 
   / JD 4300 weak front end loader #23  
Did you check the load checks???
 
   / JD 4300 weak front end loader #24  
Thanks so much for all the suggestions. I haven't yet had time to trouble shoot the issue but I have lots of good direction and it's much appreciated. I did have a brief moment to jump on the tractor yesterday to better assess the specific behavior. Here is something I noticed that *might* help to point towards the culprit. Hopefully I can explain it ok.

After startup (no weight on the bucket) The tractor will lift the FEL pretty normally but when the stick is released it will fall a little and then "settle in" and not leak down very much at all. At a high RPM the Loader will almost hold steady with no leak at all. With the slightest pull back on the loader control (to lift) the bucket will fall pretty quick, but when released back to the neutral position it will hold pretty well again. High RPM and full pull back of control will lift the bucket even with a medium load, but it will only hold that load if the control is back to the neutral position. The absolute worst position for the control to be in (to hold a load) is just a slight pull back.

I don't know the system extremely well but my gut says if a cylinder seal was blown that it wouldn't want to hold in the lifted position at all without constant pressure being applied (stick in back position). This behavior sounds more like a pressure relief valve?

thoughts?

A leaking piston seal can cause the drifting down when trying to raise slowly. The bad piston seal allows oil to flow from the cap end of the cylinder to the rod end. When trying to raise the rod end is connected to tank in the control valve.

A bad piston seal will not necessarily cause the lower to drift down with the valve in the neutral or center position. The valve blocks the flow from the cylinder when centered.

Like others have stated I suspect a bad piston seal or if this was a very sudden change one of the pistons could have come loose from the rod.
 
   / JD 4300 weak front end loader #25  
one of the pistons could have come loose from the rod.
X2 or broken piston
Have a good look at the FEL going up and see if it is square, i.e., is one side lagging, you may notice it at the top of the stroke.
 

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