Kubota B6100 with slow hydraulics

SilverLakeFab · Dec 15, 2013

Hi All,

I have been posting info and pictures about a Kubota B6100 that I mounted a Kubota LA302 FEL on. I also rebuilt the engine on this one, but that really doesn't matter here. My problem is that the auxiliary hydraulics I plumbed in for the loader, and rear set of hydraulic couplers, are super slow acting. After all the work that went into this little beast, I've only recently been able to start it. I had read that the hydraulics system on this machine would be slow, but I can only get the loader arms to raise if the engine is revving fairly quickly. I have a couple ideas how to remedy this and I'd love to get some feedback. The ideas I have are as follows.

Rebuild the hydraulic pump. Perhaps it's worn out.
Replace the tiny 1/4" hydraulic lines that came on the loader with larger ones for increased flow.
Replace the UDT with super UDT as it's darn cold in NH right now and that fluid has a lower viscosity rating.
Install a 12V booster pump for the hydraulic system.

The fluid is all new, but it has been hovering around 20 degrees F here the past couple weeks. Would anyone be kind enough to offer recommendations on this one? Perhaps there is also a different hydraulic pump that would bolt to the motor (I don't care if the lines don't match up to the ports, I can take care of that) and offer a higher flow. Any help would be much appreciated.

For those would like to see pics of the build, here's a link to that thread:
http://www.tractorbynet.com/forums/build-yourself/292031-kubota-la302-being-mounted-kubota.html

J_J · Dec 15, 2013

A hyd gage would be good to have and use to monitor and troubleshoot the hyd system.

Have you replaced the hyd filter and screen.

Look at this PDF and see if your tractor has a filter screen, and if so, clean or replace.

This PDF is for a B6100 HST.

If you can't get things to work, I can offer you a solution to your hyd problem.

Last illustration. #4

66611-36120 004 FILTER,OIL

SilverLakeFab · Dec 15, 2013

I wonder if the way I have the two valves plumbed in is causing the problem. I have attached a diagram to show how everything is plumbed. As a note, I had the rear auxiliary hydraulic ports installed before I installed and plumbed in the loader. Before all these changes, the rear ports worked fine, but that was about a year ago now. What do you think?

As a note, I also loosened the two loader arm lift cylinder connections to see if I would get air bubbles that came out, but I only got a slight drip from either connection when I tried to direct fluid to them with the loader valve. I installed the bucket and the loader arms will not lift at all, even with the revs up on the tractor. I'm leaning toward my pump not working.

J_J · Dec 15, 2013

You have paralleled your valves. Not good. Your flow is going to tank

All valves in a open center hyd system should be in series.

In your case, the pump flow should go first to the loader valve IN port, and the PB port from the loader valve should go to the remote valve IN port and then the 3pt.

SilverLakeFab · Dec 15, 2013

Your posting makes perfect sense! Of course the valves would not work in parallel. I just ran out to the shop, dug through my bucket of fittings, and welded up the fitting I needed to connect the loader valve outlet to the valve inlet line for the rear auxiliary hydraulics. I also plugged off the two ports that were empty on the distribution block, and it worked great! I've been scratching my head for two weeks on this one. You my friend, I owe a beer! Thank you so much for taking the time to give me advice.

Also, the loader works much quicker than I expected. I can't wait to put this machine to work again! Below are some picture of it working. Also, I have attached a new diagram showing how the hydraulic system now works for anyone who happens to have the same problem and finds this thread.

View attachment 350482 View attachment 350483 View attachment 350484