John Deere 200C weird issue with bucket curl

[joelmatt89]

When I hold the joystick in to curl the bucket with the machine at idle as soon as the bucket reaches the lowest point in its rotation the cylinder stops extending for a 3-5 seconds and then abruptly continues extending again at a normal speed. It doesn't matter what position the stick is in when the bucket is at the lowest point relative to the ground it does this. It's like it moves fine under the force of gravity pulling the bucket down as the cylinder extends but when the extending cylinder has to lift the bucket as it passes the low point it has to build pressure. It only does this with the bucket on and it doesn't do it when digging or at higher engine rpms or when I move really slow. In the last couple months I rebuilt the curl cylinder, installed a hydraulic thumb and rebuilt the quick coupler cylinder and I jist now noticed this issue bit I really haven't used the machine much at all lately. Today I rerouted the auxilary hydraulics to get rid of a mess of hoses which was the first time I noticed it doing this. I'm pretty carefully with open hoses etc, I really don't think it's due to contamination and I moved the cylinder quite a bit to try to work any air out. This is the only function on the machine that has any issues. Any thoughts?

 

[mg2361]

Does it go away at higher rpm's?

Your bucket regeneration circuit may not be working. There are 2 anti-cav features to that circuit. One is a circuit that is built into the bottom of the bucket spool. The second is the circuit relief for that function. It also has anti-cavitation. Try swapping the circuit reliefs to see if the problem goes away. If not, then you may have to go into the spool.

 

[joelmatt89]

Yes, it goes away at higher rpms. I'll give that a shot. So if I swap them and it doesn't go away what do you mean by going into to the spool, pull the spool? What would I be looking for? I apologize for my ignorance all my experience with hydraulic systems is just wrenching on my own stuff so my understanding is pretty limited. Thanks for your help, it is much appreciated.

 

[mg2361]

Yes, the spool. The spool gets pulled out of the top of the control valve. There is a plug on the bottom of the spool itself. It has a regeneration valve under that plug that helps regenerate oil from one side of the cylinder to the other side to help prevent cylinder cavitation. Also, if you bring the arm from all the way out to all the way in at idle, does the arm stop for a few seconds when straight down?

Why are you running at idle? If you run the engine rpm's fast enough to prevent cavitation, you can just run your machine without spending time and money. On a machine that old, the parts may be difficult to get.

 

[joelmatt89]

Thanks for the diagram and info, that's really helpful. I do not have any issues with the arm, I tried it to see when I noticed this. This machine is pretty much just used by myself for personal use, it stays on a property we're going to be building a home at and just gets used on the weekends right now My priority was mostly to make sure this wasn't an indication of a problem that could harm something if it wasn't addressed.

I was checking something related clearances on the thumb that I recently installed when I noticed this. Does it harm the machine to run it at idle under no or light load as long as your not lugging the engine? Or why do you ask?

Again I apologize for my ignorance I am by no means an operator or mechanic, I'm a mechanical engineer who enjoys getting his hands dirty but is stuck behind a desk most the time!

 

[mg2361]

Does it harm the machine to run it at idle under no or light load as long as your not lugging the engine?

So long as you are not lugging the engine, it should be fine.

why do you ask?

Those machines are not really designed to run at idle. Since it is only going to be used for "around the property", then I would just make sure you run it fast enough to prevent cavitation. Cavitation is not good for the machine. If you run it fast enough that the bucket does not hesitate, then you should be fine and have no issues.

 

[joelmatt89]

Makes sense, thanks for the info!