LA 463 Loader valve surge on L3400HST

[mike69440]

Surging, pulsing and chatter with LA463 loader on a Kubota L3400HST.

This problem just recently developed.

I believe fluid levels are where they are supposed to be. I'm not sure where to check fluid level on the L3400HST This is my neighbor痴 tractor. I am a mechanical engineer and was asked to help.

When curling back or lifting the bucket, loaded or not, the loader valve and loader movement surges, pulses and chatters.

The loader will lift a few inches smoothly, then pulse and chatter like the pump is suction starved, then lift normally a few more inches, then chatter.

This occurs at any cylinder position. I can feel and hear the loader valve pulse.

When lowering the loader arms or dumping the bucket, the hydraulic flow appears normal. Then the loader is fully curled or arms lifted to relief, the relief valve does not chatter and appears to function normally.

Any help is appreciated.

 

[kennyd]

Is the fluid foamy by chance? When was the last service done including replacing the filter and cleaning the suction screen?

 

[mike69440]

Is the fluid foamy by chance? When was the last service done including replacing the filter and cleaning the suction screen?

Supposedly the Local dealer in Tilton, NH did a $600 service at fifty hours, the tractor has 208 hours, I did an engine oil change @ 200 hrs for my neighbor as she is stuck alone now running the farm.

Where is the dip stick to check the hydraulic oil level on an L3400HST? Where is the hydraulic oil pump suction screen located?

The HST seems to be operating fine. Would not a problem with restriction in the filter or screen also cause the HST to act up? I was recently backblading with her tractor.

 

[westbrooklawn]

I'm not sure how to copy a link to another thread into a reply so I would suggest you search under my user name for a thread regarding "L3400 hydraulic leak". That thread contains a lot of the information you are looking for, and it might outline the cause of your problem.

For future use, can anyone explain how to include a link to a previous thread?

 

[Yankee Clipper]

Mike,

Take a look at the elbow hose close to the pump suction port - the rubber in these was of questionable quality and it is the prime source of air ingestion on L2800/3400 tractors.

I hope you find this to be the case.

Good luck!

 

[wushaw]

Yea what Yankee Clipper said....

 

[westbrooklawn]

Try this link to get to the thread I was referring to earlier

http://www.tractorbynet.com/forums/kubota-owning-operating/122787-l3400-hydraulic-leak.html

 

[RadarTech]

Hey guy...
There is not a dipstick for the HST fluid on the 3400..
There is a sight glass on the left side under the "transmission hump"
The fluid should be mid glass or higher...

now-- I wonder---
A few months ago when I had a leak I remember someone cautioning me on the use of teflon tape..
I wonder if someone used Teflon tape and got sloppy?

But do check out that link on leaks.

Later,
J

 

[mike69440]

Thanks all

It was a defective suction return hose. The dealer sells replacements like hotcakes.

Kubota has many parts that have been superceded with replacement parts, that have been changed, most likely to improve the durability or correct a defect. Turns out the suction return hose is one of those.

Another superceded part was the joystick control handle and switch housing on the front remote installed on my L39.

I realize legally Kubota has no obligation to support product that the have found to be of dubious design, but would it not be nice that the updated replacement parts be sold at cost to build customer loyalty?

PS
Nice place to hide that sight-glass!

 

[DRL]

Thanks for the update. I have a fairly new L3400 and will keep the info in the back of my mind. Exactly what hose was it.