3 point issue, jumpy while inactive.

[Wild and Free]

Have noticed that the three point arms settle quite fast when shut off, they will be settled all the way down after just a few hours after being shut down and when running and it is in a set position anywhere other than all the way down they sit and jump a little bit. Watching it seems it settles about 1/4+- inch every 5 seconds or so and it is just trying to compensate for the settling.
I have seen this happen on tractors with draft control but this tractor doesn't have a draft control just basic 3 point, I have adjusted the drop speed control and it makes no difference in this.
Has anyone else seen this issue and what would the fix be? Since I have had no luck finding any service manual or link to one on this site for a CT450 or a Kioti DK50SE I am hoping someone here has some experience with this issue.

 

[ovrszd]

One of two things are occurring.

1. The control valve is leaking.
2. The 3pt lift cylinder is leaking.

I'm betting on #2. The cylinder is bypassing internally and dumping the fluid back into the reservoir. As the 3pt "settles" the position control system recognizes this and activates the control valve to bring it back up to the desired position. Then it seeps off again. Then this repeats. It probably gets worse the longer the tractor is ran and the hotter the fluid becomes.

Rebuilding the cylinder is pretty straight forward. Biggest issue is that it's internal.

Under or just behind the seat is the top cover of the rear axle assembly. The two lift shafts extend out the sides of this cover. The 3pt lift linkage hooks to these shafts. Under this cover, internally is the cylinder, control valve and necessary linkage. Removing this cover becomes a bit complex. First it's surprisingly heavy. Second there may be assemblies attached to it that are cumbersome and extend beyond the hole size in the housing. This might require manipulating, turning, tilting the cover to get it free. This job is best done with a lift of some type. Most common used is a Cherry Picker or engine hoist. If you don't have one you can rig up an overhead beam on legs straddling the tractor and then use a common cable winch. I highly suggest using a lift of some kind rather than trying to manhandle it out of there.

Once it's removed you'll see the cylinder and again, it's pretty simple to rebuild.

Parts, if all it needs is new rings/seals are relatively cheap. Doubt the cylinder barrel needs replaced. But it will need honed. This can be done with a hone powered by a drill. Get all the parts necessary before disassembly to trim downtime.

Good luck with this and post any questions you might have. Lot's of knowledgeable members here that have experienced this rebuild.

 

[Wild and Free]

Yeah I have resealed a few in full sized ag tractors over the years, I used to be a diesel tech at a CaseIH dealership about 20 years ago. Mine has a cab so it gets even more interesting. I am suspecting the internal cylinder leaking down as well but just wanted to know if there was something else I needed to check on the new to me Bobcat before tearing into it too deep right away.
I have been a heavy diesel tech my entire career so its nothing big or complex to tackle but I am very **** about my work and a freak about properly troubleshooting things before ripping and tearing right away that's what drives me nuts about not being able to read through a service manual first lol.
I would like to see the hydraulic schematic to see what and if i could isolate in the system to see for sure if it is a valve or cylinder issue.
Mine is actually a bit odd, I know usually they would get worse as the oil warms up but mine actually gets better as the tractor and oil warms up i have noticed that after about a half an hour of operating the issue lessens to almost totally quits the flinching issue, go figure.

 

[ovrszd]

With your experience you are way ahead of me. Only other thing that could cause this would be a bad O-ring or gasket in the valve assembly, which you already know, also requires removing the top cover. Good luck.

 

[Wild and Free]

Yeah, I have replaced several hard and leaking o-rings already since buying this tractor which surprises me at only having 1400 hours. o-rings on Most equipment I work on daily they usually last about twice as long or longer on average before getting hard like this. Wouldn't surprise me that is an issue inside as well but I will have to put up with it until next spring / summer. can't tear into it now with winter about to bare down on us.

 

[SSdoxie]

The is a sensitivity adjustment for the 3 point MLS (positioning valve). The adjustment is set screw with a jam nut on it located next to the shaft the speed adjusting rod connects to on the front of the valve. Adjustment procedure is attach weight to the 3 pt. equal to 1/2 or more of the lift capacity. Raise until the lift arms are level. Leave engine running while adjusting the screw. I'm not absolutely sure but I think screwing in reduces jump. Once the jumps quits turn screw another 1/4 turn.

 

[ovrszd]

The is a sensitivity adjustment for the 3 point MLS (positioning valve). The adjustment is set screw with a jam nut on it located next to the shaft the speed adjusting rod connects to on the front of the valve. Adjustment procedure is attach weight to the 3 pt. equal to 1/2 or more of the lift capacity. Raise until the lift arms are level. Leave engine running while adjusting the screw. I'm not absolutely sure but I think screwing in reduces jump. Once the jumps quits turn screw another 1/4 turn.

Good stuff right there!!!! I did not know that!!! Hopefully that fixes the issue. Would be awesome if it did.

 

[Wild and Free]

Thanks SSdoxie, will definitely check this out in the next few days. Do you have a service / maintenance manual by chance or a link to one for this machine? I am coming up blank for the CT450 only stuff for the smaller rigs is to be found although I would imagine this adjustment would be no different no matter the tractor size.

 

[winston1]

Bobcat CT44, CT445, CT45 Tractor Service Repair Manual | Bobcat Manual Vault

 

[Wild and Free]

Ha Ha thanks for that one winston1 but i was hoping someone had a link to the actual manual pdf file not a site that sells them lol. Might have to break down and buy one since this one seems to be super ellusive.