RNeumann
Elite Member
I would start with the easy one- check all the QDs between the loader and valve.
JD 4300 weak front end loader
- Thread starter arkvet
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Industrial Toys
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- Kubota R510 Wheel Loader + Cab and backhoe, JD 6200 Open Station, Cushman 6150, 4x4, ten foot 56 hp Kubota diesel hydraulic wing mower, Steiner 430 Diesel Max, Kawasaki Diesel Mule, JD 4x2 Electric Gator
That would mean a lot of oil on the gorund. NOT the case here.
RNeumann
Elite Member
The QDs are a choke point for the fluid. Any little debris can get hung up in them. I’d try switching the curl and lift to see if it changes performance. Long shot? Yes! But it’s an easy check. Plus it would be part of a good systematic approach.
A second easy check, if the loader joystick is cable actuated, would be to check cable function and adjustment.
Your next step, IMHO, would be to remove hoses and cap/plug them on the lift or curl (whichever is weak) cylinder. I would do one at a time and see what happens. A bad seal in one of the cylinders will be noticeable with this test. Based on your description this is my guess...
A bad cylinder seal is more likely than the valve.
Thanks! Those do seem like easy checks and it makes sense to swap the lift / curl attachments. Let's hope it's some debris in the lines which is much simpler fix than a lift cylinder with a blown seal. I honestly am not sure if the curl cylinders are weak as well. The testing I did didn't really involve a weighted curl of the bucket. However, I will say that through the struggle to keep the lift cylinders extended I don't recall the curl cylinders trying to leak down and dump the load.
Sounds like some simple testing is in order.
Industrial Toys
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- Kubota R510 Wheel Loader + Cab and backhoe, JD 6200 Open Station, Cushman 6150, 4x4, ten foot 56 hp Kubota diesel hydraulic wing mower, Steiner 430 Diesel Max, Kawasaki Diesel Mule, JD 4x2 Electric Gator
But the cylinders are newer. I would maybe try and swap out the quick disconnects, bucket for main cylinders if possible. That could tell you if the spool has an issue provided your bucket circuit spool might also be worn.
RNeumann
Elite Member
As you can see from the video, if you have a bad seal it can play heck. They use QDs as “caps”. Obviously caps are a cheaper option.
Bypass testing a hydraulic cylinder - YouTube
Bypass testing a hydraulic cylinder - YouTube
Leejohn
Elite Member
After you do the above checks pull the relief valve seems to be stuck open a little to me.
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. Neutral holds the load. Slight pull the load falls. Full pull back and the loader struggles to lift but will lift a few hundred lbs.
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?
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. Neutral holds the load. Slight pull the load falls. Full pull back and the loader struggles to lift but will lift a few hundred lbs.
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?
Leejohn
Elite Member
Sounds like you also have a bad load check in the boom system.