Hi folks. The backhoe control jammed today, I was able to free the control but now the control is notchy and fails to return to the middle / neutral setting. A few weeks back, the loader control also jambed up...I was able to disconnect the control arm and lift the plunger in the valve a few times, it then freed up and has been working fine since. I spent a few minutes working the backhoe hoping the notchy / frozen control would go back to normal, it has not. I did a hydraulic fluid flush about 6 weeks back due to the fluid being milky. I used the VP J20a fluid because I was trying to fluch the milky fluid out. Is the fluid the problem? Did I kill the control valve? thx
Look at the mechanical pivots before tearing into it. Stuff can get bent/misaligned and not operate the spool properly.
Thx...Interesting, I noticed on of the spools popped off. I popped it back on but it is still notchy. I’ll pull the plastic cover off tomorrow and look at both of them. They are all original, 5800 hours. I might as well just replace them if they are known to go bad.
I don't know what you're planning to replace, or what is known to go bad, or even what you're calling a spool that popped off. The spool is the round metal rod that goes all the way through the valve body, it has seals at each end, the valve action is all metal on metal, or very small clearances that can be jammed easily with bits of dirt, rubber, even lint. There is a spring at the other end of the spool under a small cap, that spring controls the centering pressure that you feel. If the centering pressure is gone, then remove the cap and examine the spring. Hydraulic valves are generally trouble free, have you changed the hydraulic filter recently? did you inspect it for debris? What is the history of the backhoe?
I know most of the machines history. I’ve only had it for a few months. I’m learning it was not maintained as good as it should have been. I went out and disconnected the control / lever and excercised the valve, turned it, and continued to cycle the valve. It free’d up like the loader valve did a couple of weeks back. two pistons need new seals, I think this needs to be taken care of as I’m nor concerned about debris in the hydraulic system. Water keeps getting into the system, I believe through the piston on the backhoe during a rain event. Im going to replace the ball / knuckle joints as maintenance. I changed the hydraulic filter a few weeks back when I flushed the fluid. I’m going to change the filter again....I cleaned out the hydraulic tank with the flush, it was pretty clean... I guess if the scraper seals are bad on pistons, some dirt can enter the system... I’m new to a backhoe but not to mechanics... thx for everyone’s input.
so I could remove the two screws and retainer plate on top of the valve, and remove the valve to see what’s going on? From what I see in the parts book, this looks to be the case...
You can see the screws and retainer plate in this image...
Yes, you can remove the spool and inspect it. You'd need to remove the cap on the bottom side too. After removing the cap, you can inspect the spring which controls the "return to center" action of the spool. Like Delmer said, the spools are metal on metal with very tight tolerances. Any distortion of the bores can cause it to bind slightly. It doesn't look like yours has been removed from the machine lately. Sounding more like debris or corrosion could be the cause.
If you still have the old oil filter, cut it open and inspect for debris. Check youtube for the method, solvent rinse, or squeeze the oil out of a section of filter paper.