Kubota M4500DT 3 point won't raise

[Deep Tillage]

I recently picked up a M4500DT. The 3-pt lift arms do not go up. The auxiliary hydraulics have pressure though so I suspect the hydraulic pump works. When I dropped the hydraulic filter, I did find this piece looking like a gear tooth in the bottom (see attached). I put a glow plug in the pictures for scale.


I worked on a Ford 8N recently with same lift arm issue. Those have a common problem that the lift cylinder gets sticky if not used for a while. The fix for this on the Ford is simple- just open inspection plate and reach inside with a long pry bar. Is there a common issue with this M4500DT like this or do you suspect it's a broken linkage or gear inside causing the issue? I do not hear the relief valve when I move the control level to UP position.

 

[Motion]

I agree it looks like a broken gear tooth. It might not be the only one the one in the picture happened to make it to the filter, another one could jamming the lift arm. I wouldn't keep trying to operate the lift so as not to cause anymore problems. before pulling did you drain the oil, was there any metal flakes, pieces, etc.? View the parts breakdown and try to determine the broken part. I could be wrong but if the filter is on the discharge side of the pump it's possible that the tooth came from the pump itself and you may have two problems. Good luck

 

[DustyRusty]

Check all the hydraulic quick connect fittings. I had that same problem (less the broken gear tooth) on my BX tractor, and it was one of the couplings had come apart, interupting the fluid circuit. Easy and quick thing to check before tearing the tractor apart. The other thing that I learned about is the "O" ring seal in the lift piston can go bad, and also cause the same symptoms, that is if your tractor uses an internal lift cylinder. I have no knowledge of your series tractor, so I am only sharing my knowledge of how the BX works, and it may or may not apply to your tractor.

 

[Deep Tillage]

So when I originally tried the auxiliary hydraulics, there was some pressure there as when I bumped the lever, a stream squirted out of the faulty coupler. Since then, I drained all the hyd/tran oil and replaced with Kubota Super UDT2. I installed a brand new hyd filter screen and cleaned off the magnets in the filter housing. The filter is on the return flow right before going back to the pump. No flakes or other particles were seen which I drained the oil and cleaned the filter housing.

I removed the hyd pump/power streering pump assembly. I inspected the gear teeth while rotating and all looked fine, including the drive gear on the engine block side and driven input gear on the hyd pump. I checked the relief valve on the auxiliary hyd valve and was clean and free to move. Then I installed a gauge on one auxiliary hyd quick disconnect and 0 pressure and no relief valve noise.

Do I have to prime this hyd pump if I drained all the fluid out of it? It sits higher than the hyd oil supply so it has to suck the oil into it.

I may remove the seat and top cover on the lift mechanism next.

 

[Deep Tillage]

Check all the hydraulic quick connect fittings. I had that same problem (less the broken gear tooth) on my BX tractor, and it was one of the couplings had come apart, interupting the fluid circuit. Easy and quick thing to check before tearing the tractor apart. The other thing that I learned about is the "O" ring seal in the lift piston can go bad, and also cause the same symptoms, that is if your tractor uses an internal lift cylinder. I have no knowledge of your series tractor, so I am only sharing my knowledge of how the BX works, and it may or may not apply to your tractor.

Where was your fluid circuit interrupted?

 

[DustyRusty]

Where was your fluid circuit interrupted?

It was one of the quick disconnects on the BX22 loader valve, but I can't tell you exactly which one. When I checked them, one had disconnected, and I just pushed it back together. This has been a problem with the disconnects since the tractor was new, and a couple of them were replaced by the dealer, and nothing changed.