L3400 Jerky 3 Point

[Paulwestski]

I ordered a L3400 two weeks ago and then this week I'm reading about the three point on most LXX00 series are not smooth to operate as they should be.
I read somewhere that if the three point control valve is swapped with a Grand control valve it would be smooth as silk.
Does anyone know if this would work??? How much would just the parts cost?

 

[eserv]

Some of the early L3400's developed "jerky" tph's because of a failure of a suction hose to the Hydraulic pump allowing air into the oil. This is not a problem on new ones. I have to ask though, why order a L3400 when a new L3800 can be had for very little more money?

 

[Paulwestski]

Some of the early L3400's developed "jerky" tph's because of a failure of a suction hose to the Hydraulic pump allowing air into the oil. This is not a problem on new ones. I have to ask though, why order a L3400 when a new L3800 can be had for very little more money?

That's the first I've heard of a suction issue on the hydro circuit. Everything I've read leans toward TPH valve quality on the LXX00.

I should rephrase "ordered" it was the last one on the lot and I got a pretty sweet deal on it. The dealer had to order some of the attachments and install the FEL and BH.

That very little more money based on Kubota's window sticker was enough to put the package over my budget or forgo an attachment. since I got a sweet deal on the L3400 the L3800 was considerably more money.

Cruise control and draw bar are optional on the L3800 but included on the L3400.

 

[eserv]

You are right, there were some pretty sweet deals on the last of the L3400s.
The cruise control is optional on the L3200-3800, drawbar is standard. The L3700 doesn't have either a drawbar or cruise control standard.

 

[eserv]

See this thread
http://www.orangetractortalks.com/forums/showthread.php?t=2561&highlight=suction+hose

 

[Paulwestski]

See this thread
http://www.orangetractortalks.com/forums/showthread.php?t=2561&highlight=suction+hose

Thanks
I've been searching the forums for discussion and haven't seen this one.

 

[J252]

I am in the middle of tackling this problem on my own recently acquired used L3400. Be sure you try the machine out in the yard (with an implement) and see how it is before you take delivery.

For those not familiar with this problem, it is well covered in other tractor forums. The OP is referring to the jerky Position Control Valve used on the L2800/L3400 models that did not have the optional draft control. (The units with draft control got a better position control valve.)

http://www.youtube.com/watch?v=Y4F_IjO1YFw&feature=related

http://www.youtube.com/watch?v=AS5VN8McI2Y

The problem appears to be a combination of too high a rate of hydraulic fluid flow into the 3PH lift cylinder, poor CV proportional response (more like all or nothing), and a large hysteresis in the control valve itself causing the 3PH to jump up in discrete steps of 1" (and overshoot its set point via momentum and then bounce back). With a heavy implement on the back it can get quite scary and violent bouncing the whole tractor.

As per the parts book, Kubota used 4 different control valves on that tractor throughout the model run. They vary quite a bit in smoothness, and I'm not sure how good the latest ones are. Mine is an older L3400 with the original control valve.
Try your tractor out first and see how it is. If it is problematic, you can find out using the parts book and serial number which control valve you have.

To upgrade, you will to swap out the control valve for part# 31351-39604 which costs about $450.
The end result is a smoother operation (though still twitchy), with the 3PH response being small jumps of about 1/4". It still won't be quite as smooth as most other tractors, but good enough.

http://www.youtube.com/watch?v=KsUFc5KesF8

 

[J252]

__________

 

[eserv]

I wonder how many $450 valves are being replaced because a suction hose has a small leak? I have corrected every complaint about jerky loaders, power steering and TPH's by replacing that hose!
Ed

 

[J252]

I wonder how many $450 valves are being replaced because a suction hose has a small leak? I have corrected every complaint about jerky loaders, power steering and TPH's by replacing that hose!
Ed

I definitely agree with the philosophy of proper diagnosis, and not replacing items willy nilly. I also know that these tractors do have a problem with the rubber section of the pump suction hose leaking. However, on the units affected by control valve woes, the jerky operation problem happens from day 1, doesn't vary over time (ie: get worse), and doesn't involve the loader. If the suction hose is leaking, both the 3PH and the FEL will operate erratically.