B3300SU LA504 front end loader control valve won't curl

[DCReich]

Hi all,

Yes, I know this has been discussed before, I've picked up some great information. I just want a little confirmation I'm on the right track.

Our tractor has been through about 420 hours of good times, the FEL is regularly used for digging rocks out of a field, moving piles of gravel, dirt, rocks, etc, and for snow plowing in the winter.

Yesterday I was moving some dirt when the bucket went into full uncurl, it seemed to have a mind of its own. It slowly responded to the control but soon repeated the action. I took the tractor back to the barn. Fluid was a little low but not bad. The three point hitch was carrying a box blade and behaved just fine, so did the up/down of the FEL, but when I next tried the curl/.uncurl it was jammed in place. I couldn't move the joystick left or right. I inspected the stick and control mechanism on top of the control valve body, cleaned out some bits to dead grass but found nothing stopping the stick from moving. When I next tried the curl/uncurl the bucket went into full curl and now I can not move the stick to the uncurl position.

From reading past posts I'm pretty confident the inner workings of the control valve have come apart and the valve needs to be rebuilt or replaced. I'm fairly handy and could replace old parts with new but am afraid I'll find irreparable damage. I also don't want to repair it with parts that are likely to fail so it seems best to replace the valve with the updated strengthened version.

My questions
- anything else I should check?
- Does my conclusion seem sound?
- is there a good source for a new valve at a "reasonable" price?

Thanks in advance for any and all help help!
Dave

 

[Dave B.]

This just happened to our B3300SU - after tearing a hydraulic hose on FEL. Replaced the hose and lost the bucket curl - all other FEL functions worked well - cracked the oil lines leading to the bucket - no oil on the bucket return cylinder. Press in on the joystick to curl bucket back - audible sound of the pressure relief valve kicking in on the HST pump. Next replaced the hydraulic hose fitting attached to hard lines leaving the spool valve (the barbed fitting that the quick-connect hoses attach to when removing the loader arms)..turns out that when the hydraulic hose was originally torn - it shocked the pressurized side of the hydraulic lines...blew out an o-ring at the spool valve & also damaged the fixed barbed fitting...this was hard to troubleshoot as the spring-loaded center valve was still working. Removed the barbed fitting and looked inside with a bright flashlight the 3 spring-loaded arms that hold the fitting into the inner flange had blown out on all 3 contact points - when attaching the new hose to this barbed fitting - it was still pressurized, press in on the center valve after releasing pressure using the joystick functions - must have turned the 3 spring-loaded arms about 1/4 turn - so that they were once again seated on their inner flange - with 3 obvious blow outs in the flange...the broken flange pieces were jammed into the tip of the barbed fitting - which is why there was restricted (almost none) oil flow. The new barbed fitting only cost $8 at the hose shop - FEL curl function started working immediately without bleeding any additional air from the hydraulic system.

 

[whitetiger]

My questions
- anything else I should check? Does the control lever move back to neutral with the engine shut off?
- Does my conclusion seem sound? Hardly
- is there a good source for a new valve at a "reasonable" price? Perhaps you should diagnose the issue before jumping to very expensive and unwarranted conclusions as a complete valve failure is all but unheard of.

If the control lever will not return to neutral with the engine shut off, the likely failure is the detent assembly on the end of the spool. Replacing the detent assembly is a very simple procedure and wayyyyyyy cheaper than replacing the control valve assembly.
There just are very few pieces to these valves and the issue is almost always the linkage on the lever or the detent assembly.