Kubota KX161 / KX121 info help

[reinhs]

Hi All,
I'm looking for some model year guidance on a Kubota KX161-3SS or maybe KX121-3SS excavator. I have a 161-3SS and the manual to go along with it. The problem I'm having is the thumb will not stay in the retracted position. It drifts slowly back down towards the bucket. I've read that can be caused by the one-way / two-way valve being in the wrong position. I don't seem to have one on mine best I can tell. Are all SuperSeries supposed to have that valve and the third hose return for the aux port?

Also, all the descriptions for this model talk about being able to adjust the flow for the aux/service port using the digital panel. My manual doesn't mention anywhere about flow adjustment and I can't seem to figure out a way to do it using the panel. If I push the aux port button it comes on. If I push it again it shuts off. I've pushed every button I can think of in every combo and can't find any way to adjust flow rate for the aux port.

My machine is around SN 31,000. I think SuperSeries 161 production started at 30k so it's one of the first 1000 machines. Did earlier KX161-3SS (Super Series) not have the one way / two way aux/service valve for thumbs or breakers? Are earlier digital panels less capable than newer models even though they look identical?

Is it even possible to adjust my Aux port flow rate to the thumb? Anyone know how to fix the thumb drifting from the "stowed" position? It's solid in the clamp position. Fixing the thumb is my real end goal of course, but it's confusing that I can't find a single description of a 121 or 161 Super Series that doesn't have the one-way / two-way valve or an inability to adjust the flow rate.

Anyone have any experience with this? Many thanks!
Senter

 

[Tags]

I have a late model 161-3, not an an S version, so it has no digital panel in it but it does have auto idle. I run a hammer on mine and do not need to turn any valves to allow fee flow back to the tank, because it has no such valve on it that i have ever found anyway. Try pressing and holding the Aux port button to adjust the flow. If your machine doesn't have a lever or valve to switch to free return on one of the auxilliary line then you may have fluid bypassing the packings in the thumb cylinder. I had this happen years ago on a machine with a thumb. Remove the cylinder and bring it to any reputable hydraulic shop and they should be able to install new packings in it and you should be all set.

 

[reinhs]

Greetings Tags, thanks for the input! It's good to hear from another user on how their machine works. I'd tried holding down each of the buttons and in combination, but no go. Tried it with the machine off but switch to run position also. It would be interesting to hear from someone who's able to adjust the flow on a newer machine and see what they are doing. I think the manual I have is the most recent manual for the Super Series and it doesn't mention how to change the flow either though they seem really proud of the feature on their website.

As far as the cylinder packing, that sounds like a good possibility. The only strange thing is that the thumb is solid on clamp. Will hold position all day. On retract though, as soon as I let go of the control the weight of the thumb instantly starts to bring it out of retract. I can walk up to it and pull on the thumb and easily move it towards the bucket. There's resistance of course but it doesn't take much effort. It's done this since I bought it. It's like a check valve it totally shot, the mystery one-way/two-way that seems missing isn't in the right position, or like you said, there is a massive leak in the packings.

Thanks for any additional thoughts and I'd love to hear from anyone else driving one of these machines. Thanks again,
Senter