Kubota B7300 Hydraulics Issue

[Keystone B7300]

So I searched for an answer to my problem but I couldn't find it. The tractor in question is a B7300 HST around 750 Hours. I hope someone knowledgeable can help me with this. I recently changed all of the fluids, filters, and cleaned the screen on the banjo bolt and the 3 point hitch functioned properly for ~1 use. After letting the tractor sit for a few weeks I started it up this weekend and the 3 point hitch would not lift (always drop it down and then put it in the "Neutral" Position).
After doing some troubleshooting the hydraulic pump isn't getting fluid from the reservoir at the back of the tractor. Attached is a diagram to show the parts I am talking about. I pulled the rubber hose (#70) off of the supply pipe (#40) and fluid barely trickled out. I've tried cracking the high pressure side (#160) to see if any air pocket can pass and no luck. I read somewhere that you might have to overfill the reservoir in order to "Prime" the pump, but no luck. I couldn't find any sort of air bleed on the pump.
I finally decided to crack the banjo bolt and once freed from the housing fluid flowed very well not out of the end of the pipe but where the banjo bolt goes. It almost seemed like the screen on the banjo bolt is too fine to let the fluid run through it quickly. I double checked and the screen was clean.
I used Traveller Universal Tractor Trans/Hydraulic Fluid from tractor supply.

My questions:
Should fluid freely flow out of the end of P/N 40 if I removed it from the rubber hose (#70)? or would the pump cause a vacuum and suck the fluid towards it?
Should the pump self prime?
Is there a way to Prime the line?

I don't think the pump is bad and I only ran the pump for short intervals to not damage it. It almost seemed like I lost prime when the tractor sat or when I previously changed the fluids.


Appreciate the help in advance.

 

[Dave_eng]

Using non Kubota fluids especially when you have a HST is not wise.

Your fluid may be too viscous for the suction screen.

With the proper fluid and with the O rings (#50 )changed , the rubber pipe in excellent condition the pump should self prime.

Do not run it with the pump not moving fluid or you can destroy the pump.

With the engine stopped, remove the high pressure pipe and pour some fluid into the pump body.

Crank the engine with the high pressure pipe removed to see if the oil will start to flow.

Even if this gets it working, seriously consider getting the proper hydraulic oil.

Dave

 

[Keystone B7300]

Using non Kubota fluids especially when you have a HST is not wise.

Your fluid may be too viscous for the suction screen.

With the proper fluid and with the O rings (#50 )changed , the rubber pipe in excellent condition the pump should self prime.

Do not run it with the pump not moving fluid or you can destroy the pump.

With the engine stopped, remove the high pressure pipe and pour some fluid into the pump body.

Crank the engine with the high pressure pipe removed to see if the oil will start to flow.

Even if this gets it working, seriously consider getting the proper hydraulic oil.

Dave

Dave thanks for the reply. I will fully drain the remainder tomorrow. I only ran it short bursts while trying to troubleshoot. It does seem like maybe the fluid might be too viscous. Can you recommend a good UDT fluid (Valvoline?), or just Kubotas own brand? I'll try to get some fluid into the high pressure side once I pickup some better fluid. I believe all hoses are in good shape.
That's what I get for trying to save some money.

 

[Dave_eng]

Dave thanks for the reply. I will fully drain the remainder tomorrow. I only ran it short bursts while trying to troubleshoot. It does seem like maybe the fluid might be too viscous. Can you recommend a good UDT fluid (Valvoline?), or just Kubotas own brand? I'll try to get some fluid into the high pressure side once I pickup some better fluid. I believe all hoses are in good shape.
That's what I get for trying to save some money.

Often on this forum, owners with sophisticated hydraulic systems come to grief in the quest for cheaper alternative fluids and filters.

I am not talking about gear transmission tractors like a L 175 but HST tractors.

Stick with Kubota. Then if you have a problem you know it is not the fluid.

Dave

 

[Keystone B7300]

Often on this forum, owners with sophisticated hydraulic systems come to grief in the quest for cheaper alternative fluids and filters.

I am not talking about gear transmission tractors like a L 175 but HST tractors.

Stick with Kubota. Then if you have a problem you know it is not the fluid.

Dave

Thanks I understand. Should have gone with the right stuff from the beginning. Picking up the o-rings, Kubota UDT and a new screen just in case tomorrow. I'll have it put back together this weekend.

 

[Keystone B7300]

Well put the UDT in it, replaced o rings, double checked the screen, took the hose (#70) off and inspected it. I took the rubber hose off the pump (#70) and used some small tubing and a syringe to put some fluid in the pump to "prime" it. It seems that the pump is bad. I just don't get that it randomly failed completely. Is there a rebuild kit or something available?

 

[Keystone B7300]

Or is there any other troubleshooting ideas? I can't get fluid to follow well though #40. Even though the screen is clean

 

[Keystone B7300]

I got it to finally work. Just hoping this helps someone out. Just basically kept trying. I took the rubber hose off the pump but left it connected to the pipe and by doing this let the air escape in the line. I then syringed fluid into the actual pump and quickly closed it back up and started it. It took a few seconds but could hear the pump trying. Eventually it purged the line.