Kubota BX25D - Backhoe return line/quick connect getting hot

[sea2summit]

Have you checked the couplers? If a male coupler is on the tractor side it might not getting opened with the female coupler.

Facepalm.

If it's not open the tractor will not move, to test it just unhook the hose and try to drive. Don't try it often or for long as it is going to cause damage/prematurely wear the relief valve.

 

[ptsg]

Facepalm.

If it's not open the tractor will not move, to test it just unhook the hose and try to drive. Don't try it often or for long as it is going to cause damage/prematurely wear the relief valve.

Why wouldn't it move?

 

[sea2summit]

Why wouldn't it move?

Because when the excess flow of a priority control valve is higher than the controlled flow it shuts the valve returning all fluid to tank via the relief valve.

 

[analog]

If the return gets hot and the feed line doesn’t then I would say you have a restriction in that return fitting. Like what was already mentioned flow is continuous so they should both be the same temp. But they will be hotter than a fitting on the work ports of the loader or backhoe.

Look forward to seeing what the actual temps are. That will tell us a lot.

I would like to know what kind of restriction there would be. Would leaks cause heating up? I could see something being in the line as far as a restriction goes, but I would expect the filter to catch that before it ever circulates back to the backhoe? I suppose I could depress the balls in the line to see if they move properly.

I guess I should see if there is a hydraulic troubleshooting guide out there somewhere.

 

[DB Pilot]

Because when the excess flow of a priority control valve is higher than the controlled flow it shuts the valve returning all fluid to tank via the relief valve.

Sea2summit, I have the Kubota BH77, Last year the the dipper stick would not extend. I had that fixed at a huge cost. After the "repair" the backhoe would creep to the right when sitting still, but the BH was usable. This year, at spring startup, I find that the BH moves very slowly and weakly to the left and can be assisted by hand. It moves very quickly to the right then, I can get it to very slowly center up. I thought your continuous flow explanation would explain the creeping to the strong right side vs the weak left side movement. Everything else boom, dipper stick and bucket seem to be working quickly and strong.

Seems to me you know a little bit more about hydraulics than the mechanics here, as all I get from them is, we will look it over. Feels like I am paying them to learn the system. I did learn about spool valves on youtube, but I might be just throwing money at the BH just hoping thats the problem. Any insights would be appreciated.

 

[sea2summit]

Sea2summit, I have the Kubota BH77, Last year the the dipper stick would not extend. I had that fixed at a huge cost. After the "repair" the backhoe would creep to the right when sitting still, but the BH was usable. This year, at spring startup, I find that the BH moves very slowly and weakly to the left and can be assisted by hand. It moves very quickly to the right then, I can get it to very slowly center up. I thought your continuous flow explanation would explain the creeping to the strong right side vs the weak left side movement. Everything else boom, dipper stick and bucket seem to be working quickly and strong.

Seems to me you know a little bit more about hydraulics than the mechanics here, as all I get from them is, we will look it over. Feels like I am paying them to learn the system. I did learn about spool valves on youtube, but I might be just throwing money at the BH just hoping thats the problem. Any insights would be appreciated.

I am absolutely not a professional! Didn’t even sleep at a holiday inn.
I do enjoy figuring out how to fix things myself which often involves destructive testing

But it sounds to me like you have some bad seals in your control to me. Possibly damaged when the took it apart for the dipper? That’s pure speculation, I’d have to look at the flow chart and see how they are or aren’t related.

 

[DB Pilot]

Sea2summit, Thanks for the possible bad seal Idea. I also like to fix things myself. I must be good at it, as I always have extra parts left over after putting stuff back together.
I took the machine to an off brand dealer who was closer but I will get to the Kubota dealer this time.