LA 463 Loader valve surge on L3400HST

  Aug 31, 2009 / LA 463 Loader valve surge on L3400HST

#1  

mike69440

Elite Member

Joined

Jun 2, 2005

Messages

3,303

Location

Central NH (God's Country)

Tractor

2005 L39 Kubota, 2020 Polaris 570 Sportsman, 2006 RTV 900, 2019 RTV1100C, 1997 Komatsu PC75UU2E w/ Thumb & Blade, 2013 Mahindra Max28XL Shuttle plus many attachments

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.

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

#2  

kennyd

Advertiser

Joined

Jul 6, 2003

Messages

13,755

Location

Westminster, MD

Tractor

John Deere 3720 CAB/TLB, JD455

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

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

• Thread Starter

#3  

OP

mike69440

Elite Member

Joined

Jun 2, 2005

Messages

3,303

Location

Central NH (God's Country)

Tractor

2005 L39 Kubota, 2020 Polaris 570 Sportsman, 2006 RTV 900, 2019 RTV1100C, 1997 Komatsu PC75UU2E w/ Thumb & Blade, 2013 Mahindra Max28XL Shuttle plus many attachments

kennyd said:

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

Click to expand...

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.

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

#4  

westbrooklawn

Platinum Member

Joined

Apr 22, 2005

Messages

633

Location

North Carolina

Tractor

kubota L3400HST

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?

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

#5  

Yankee Clipper

Gold Member

Joined

Sep 6, 2007

Messages

292

Location

Western US

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!

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

#6  

wushaw

Elite Member

Joined

Mar 6, 2005

Messages

3,190

Location

Bristol Texas

Tractor

Kubota L2800, 15 hp 372 Mitsubishi

Yea what Yankee Clipper said....

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

#7  

westbrooklawn

Platinum Member

Joined

Apr 22, 2005

Messages

633

Location

North Carolina

Tractor

kubota L3400HST

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

 

  Sep 1, 2009 / LA 463 Loader valve surge on L3400HST

#8  

RadarTech

Elite Member

Joined

Feb 17, 2008

Messages

2,752

Location

North Carolina

Tractor

2007 Kubota L3400, YANMAR YT359C

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

 

  Sep 3, 2009 / LA 463 Loader valve surge on L3400HST

• Thread Starter

#9  

OP

mike69440

Elite Member

Joined

Jun 2, 2005

Messages

3,303

Location

Central NH (God's Country)

Tractor

2005 L39 Kubota, 2020 Polaris 570 Sportsman, 2006 RTV 900, 2019 RTV1100C, 1997 Komatsu PC75UU2E w/ Thumb & Blade, 2013 Mahindra Max28XL Shuttle plus many attachments

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!

 

  Sep 3, 2009 / LA 463 Loader valve surge on L3400HST

#10  

D

DRL

Silver Member

Joined

Sep 15, 2007

Messages

139

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.