Loader - LA271 - Deadzone at full lift

[ben1272]

Hello, my barely used (150hr) LA271 has a new phenomenon when I try to use the controller to lift the bucket. As I move joystick down to lift bucket, it lifts, but at full joystick deflection, lift stops. I have heard this can be related to 3 point hitch pressure relief valve? Its a B7300 tractor, and a backhoe is fitted. I cant tell if my 3pt is full up to the point of triggering relief valve, but I have tried raising and lowering it while trying to raise and lower FEL and have not noticed any observable impact. I may take off backhoe to see if problem goes away.

Otherwise, I have removed quick disconnects, cleaned/lubed, checked for blockages, etc. Seem to be OK. I have not tried swapping lift with tilt to see if problem follows hoses to the other function....I assume it would, but I have not tried.

Any ideas out there? It is frustrating trying to use it this way.

 

[TheOldHokie]

Hello, my barely used (150hr) LA271 has a new phenomenon when I try to use the controller to lift the bucket. As I move joystick down to lift bucket, it lifts, but at full joystick deflection, lift stops. I have heard this can be related to 3 point hitch pressure relief valve? Its a B7300 tractor, and a backhoe is fitted. I cant tell if my 3pt is full up to the point of triggering relief valve, but I have tried raising and lowering it while trying to raise and lower FEL and have not noticed any observable impact. I may take off backhoe to see if problem goes away.

Otherwise, I have removed quick disconnects, cleaned/lubed, checked for blockages, etc. Seem to be OK. I have not tried swapping lift with tilt to see if problem follows hoses to the other function....I assume it would, but I have not tried.

Any ideas out there? It is frustrating trying to use it this way.

If it raises initially the circuit is not blocked. Sounds more like the spool is over extending and closing off the lift work port. Maybe something in the valve broke or perhaps an adjustment in the joystick linkage.

Dan

 

[ben1272]

If it raises initially the circuit is not blocked. Sounds more like the spool is over extending and closing off the lift work port. Maybe something in the valve broke or perhaps an adjustment in the joystick linkage.

Dan

Is there anything about these valve assemblies that makes them difficult to re-assemble once they get pulled apart? I know there are small balls/spring at one end that look like they would be a challenge to get back together, but I am unfamiliar with the internals and dont want to take something apart that I will never get back together. I can get the valve assembly off the tractor easy enough.....all the springs/balls/orings/unknowns make me nervous that I'll never get it back together!

EDIT: Answer to this question is...YES, there are the detente balls (4 of them, smaller) and the one larger actuator ball, and the spring that goes with it all. Watch it as it comes apart. I am lucky mone didnt launch itself across the garage. It tried once or twice, eventually my son helped compress things while I slid on the keeper. The LA271 workshop manual did not get into valve service much, but has some nice cross-sections.

 

[TheOldHokie]

Is there anything about these valve assemblies that makes them difficult to re-assemble once they get pulled apart? I know there are small balls/spring at one end that look like they would be a challenge to get back together, but I am unfamiliar with the internals and dont want to take something apart that I will never get back together. I can get the valve assembly off the tractor easy enough.....all the springs/balls/orings/unknowns make me nervous that I'll never get it back together!

Sounds like uou are not real experienced. I would suggest you look at the external linkage before trying to disassemble a valve with only 150 hours on it.

Dan

 

[ben1272]

Yeah, not super experienced with hydraulics, but learning every time I dig into the kubota. I've had it since new, almost 25 years. I found a good video that shows a control valve coming apart, looks like should not present any particular problem, other than the detente balls/spring re-assembly. An oak tree did fall on the poor tractor (snapped an axle, crushed roll bard) also just caught and bent FEL joystick. I think that is when it started mis-behaving. I am going to remove backhoe first to make sure it is not related to its installation, and then I will dig into controller valve.

While the linkages have a little slop in them, they seem OK (thats where I started). There is not enough adjustment in the threaded clevis to limit the overtravel, I tried that too, I think it is time to disassemble the valve and learn something new.

 

[TheOldHokie]

Yeah, not super experienced with hydraulics, but learning every time I dig into the kubota. I've had it since new, almost 25 years. I found a good video that shows a control valve coming apart, looks like should not present any particular problem, other than the detente balls/spring re-assembly. An oak tree did fall on the poor tractor (snapped an axle, crushed roll bard) also just caught and bent FEL joystick. I think that is when it started mis-behaving. I am going to remove backhoe first to make sure it is not related to its installation, and then I will dig into controller valve.

While the linkages have a little slop in them, they seem OK (thats where I started). There is not enough adjustment in the threaded clevis to limit the overtravel, I tried that too, I think it is time to disassemble the valve and learn something new.

Just remove the end cover on the boom spool and inspect that mechanism. No need to tear the entire valve apart or remove the spool.

Dan

 

[jyoutz]

Yeah, not super experienced with hydraulics, but learning every time I dig into the kubota. I've had it since new, almost 25 years. I found a good video that shows a control valve coming apart, looks like should not present any particular problem, other than the detente balls/spring re-assembly. An oak tree did fall on the poor tractor (snapped an axle, crushed roll bard) also just caught and bent FEL joystick. I think that is when it started mis-behaving. I am going to remove backhoe first to make sure it is not related to its installation, and then I will dig into controller valve.

While the linkages have a little slop in them, they seem OK (thats where I started). There is not enough adjustment in the threaded clevis to limit the overtravel, I tried that too, I think it is time to disassemble the valve and learn something new.

The most likely cause is the bent joystick incident. I would look there first.

 

[TheOldHokie]

The most likely cause is the bent joystick incident. I would look there first.

I agree but he says he has already checked that out

Dan

 

[ben1272]

Ok, I'm back and I think successful. I disassembled the lift valve and wire brushed a bit of corrosion that had overtaken the spring. The balls all looked good. Tricky to get it back together, but with a helper it was not too bad. The LA271 Workshop Manual has good cross-sections in it that helped me get everything right.

When I tried the lift after this cleanout it seemed to be only out of adjustment a bit. I checked how much threaded clevis I had left and was able to make an adjustment, in conjunction with the joystick shaft dead stopping against the opening in the protective cover, and I was able to get it back into proper operation! I think the tree knocked things out of adjustment and in conjunction with the common corrosion going on inside the spring/detente assembly on the lift valve, it conspired against me.

The whole exercise gave me a great excuse to disconnect all of the hydraulic quick-disconnects and clean them out.....most of them were corroding in ways that were not good. I also like to re-assembly things with a touch of antiseize on them.....future self thanks me in advance. I'm glad it is working right again. It was real annoying to use this way.

Thanks to those who took the time to weigh in.

 

[ben1272]

Just remove the end cover on the boom spool and inspect that mechanism. No need to tear the entire valve apart or remove the spool.

Dan

This is what I did. I left everything on the tractor. A bit of tight quarters, but it was doable.