Backhoe KUBOTA BACKHOE HELP,PLEASE!!

[COMPRESSOR]

I purchased a new B7800 kubota and shortly after had a bh75 backhoe attachment install.
My problem is the first time I dug with it I noticed that it had very little power.
The tractor hyd are so weak,if you put the stabilizers down the front bucket will not lift the tractor off the ground.
I took the tractor back to the dealer and they told me the tractor was ok.
I have put up with this now for almost 2 years.Well,yesterday my neighbor came over and ask me if I would dig a 30 foot long trench about 1 foot deep.
Being the nice guy I am,I jumped at the chance.Not only to be the good guy of the neighborhood,but to be able to use my play toy.
Can you say,almost WORTHLESS!
My question is. Could there be anyone out there in kubota world that could tell me where the relief valve is located? I have adjusted the ones one the attachment several times,that's not my problem.I need to set up the relief valve at the pump,but can't seen to find it.I did put a gauge on one of the cylinders on the hoe. 1500 lbs.
Please don't respond and tell me not to set it up because you'll ruin something.
Trust me, I'll take the chance.
CERTAINLY, THERE MUST BE A GUY OUT THERE,MAYBE A KUBOTA TECH OR MAYBE ONE OF THOSE OLD GUY'S THAT WELL, THEY SEEM TO KNOW EVERYTHING.
THANKS IN ADVANCE COMPRESSOR

 

[KennyV]

Someone else posted this a while back it should get you in the area. Your valve should be around this same place. Good luck. KennyV.

 

[COMPRESSOR]

KENNYV,
Thank you so much for taking the time to post those pictures.The only problem is mine is a B7800.The pictures you posted were for another size of tractor.Mine does not look like the one that was posted.
Any ideas???????????? Thanks again: COMPRESSOR

 

[Wayne_Freeman]

Go here and download the B7800 parts manual. Index of Kubotabooks/Tractor/ Your valve is on page 127 and the shims are item 090. I assume they work the same as what you saw in the above post. Adding shim will increase pressure. It looks like you have a gauge so be sure and use it to see how much change you have made. For shims you can remove what is already there to get an idea of size then go to a good hardware store and get some similar washers the same size. I tweaked mine up on my L3400 because I think from the factory they are on the low side. Let us know how you make out.

 

[LBrown59]

yesterday my neighbor came over and ask me if I would dig a 30 foot long trench about 1 foot deep.
Being the nice guy I am,I jumped at the chance.Not only to be the good guy of the neighborhood,but to be able to use my play toy.

Do you have insurance that covers everything when you are off your own property with the tractor?
Also don't forget to call (CALL BEFORE YOU DIG) before you dig.
A 1 foot deep 30 foot long ditch is a piece of cake for my bx23

 

[savageactor7]

Compressor the only thing I can think of is that you make sure when you use the backhoe that the tractors rpm's are in the pto range. If you're doing that already my apologies. But one of my neighbor's complained of the same thing...when he raised the rpm's...no problem.

 

[COMPRESSOR]

Wayne,
Thanks for the response,I went to page 127 as you said ,but cannot locate it on my tractor. Thanks anyway COMPRESSOR

 

[Wayne_Freeman]

Page 125 item 010 will put you on it relative to the entire assembly.

 

[COMPRESSOR]

Wayne,
is that accessible under the tractor ,or do i have to take the top of the housing off ?That lookes like quite a job.It is hard to tell by the picture.
THANKS AGAIN FOR YOUR TROUBLE !!!! compressor

 

[bandit67]

I know this isn't pointing you in the right direction as far as the relief valve is concerned, but my B3030 with 9.1 gpm flow (your B7800 is 9.5 gpm) with the BH75 digs just fine from 1700 rpms on up. I've been digging in some extremely rocky ground, and had a chance to dig in non-rocky ground last week, and couldn't believe how easy that was.

I've used quite a few bigger hoes, and am extremely impressed with the power of the BH75, so it appears that something is definitely wrong with your setup. Good luck in finding a fix.

 

[Wayne_Freeman]

My guess is it is under your seat but not having a machine like yours and being a very average shade tree mechanic I can't be of much help. Maybe one of our 7800 owners or a mechanic can give you a heads up.

 

[irwin]

Wayne,
is that accessible under the tractor ,or do i have to take the top of the housing off ?That lookes like quite a job.It is hard to tell by the picture.
THANKS AGAIN FOR YOUR TROUBLE !!!! compressor

Although I don't have this tractor and can't be one hundred percent sure...
I'll jump in here. According to B7800 parts info... no, not under tractor....yes you have to take the top off, it's more than a couple bolts, but it appears that it's still just bolts, nuts, studs etc. Depending on your abilities (if you're not afraid to replace head gaskets on a car ) go for it, or (if changing oil and filter sums up your mechanical experience) get help.

However from your description of the dismal hydraulic pressure, I have one question: Does your loader have all the power needed when the backhoe is off the tractor? well... 2 questions: what's the pressure without the backhoe on?

You may have some other problem with the hydraulics..(suction line leak) or a problem with the backhoe hydraulics.. Have a pro look at this, get a diagnosis then you can do a fix. JMHO

 

[N1ST]

Sorry, this isn't going to help you debug your problem, but for what it's worth, a middle buster plow (about $100 bucks at TSC depending on the brand) would dig the trench your neighbor wants in less than 5 minutes.

 

[COMPRESSOR]

IRWIN,
Thanks for the input.
As far a the loader performance, it is marginal as best.I do however have the larger bucket,but still you would think that a load of gravel or ETC would not be a problem.With the bucket loaded it struggles. I remember my old faithful b8200,that loader would almost pickup the back of a truck.Maybe I am just exspecting to much for my 20.000.00 or so investment.
THANKS AGAIN IRWIN FOR TAKING THE TIME FOR YOUR INPUT.
COMPRESSOR

 

[bandit67]

I rented a B7800 last fall when I was between tractors to move 30 tons of stone, and I was very impressed with the power of the loader. It was very responsive, and helped lead me to my current machine.

Something must have been wrong now with your machine for the last couple of years. I was impressed with the overall capabilities of that little machine after using a larger L35 TLB and a full size TLB around the same time on the same property.

Sounds like you may need to find another dealer service department to do some troubleshooting because something doesn't sound right at all.

 

[alchemysa]

IRWIN,
Thanks for the input.
As far a the loader performance, it is marginal as best.I do however have the larger bucket,but still you would think that a load of gravel or ETC would not be a problem.With the bucket loaded it struggles. I remember my old faithful b8200,that loader would almost pickup the back of a truck.Maybe I am just exspecting to much for my 20.000.00 or so investment.
THANKS AGAIN IRWIN FOR TAKING THE TIME FOR YOUR INPUT.
COMPRESSOR

There's clearly something wrong here, and its probably something very simple. Your loader and backhoe should be able to eat my little 1550 for breakfast. Get some advice from someone who knows what they are talking about. Check the position of the 3 point hitch lever. I think I recall something about it having to be in a full up position or the loader will be 'weak'.

 

[Farmerford]

From the parts diagram, it appears that the relief valve you are seeking is at the TPH, which is the end of the system (the last device in the hydraulic circuit). If your FEL and remote/backhoe hookup are typical, they both connect into the system at the manifold block in the line from the pump to the TPH, usually below the right foot rest. When connected, the flow is diverted from the TPH to first the FEL, then the remotes/BH, then back to the manifold block and on to the TPH.

If that is true, the relief in the TPH does not affect upstream pressure because it is taken out of the circuit when an upstream spool is shifted to send fluid to a valve. That also means that there is no system relief that protects the entire system (unless the only device is the TPH). I suspect there is a relief in the FEL valve because it can not rely on the one at the TPH. Since the BH is probably downstream of the FEL, the FEL relief also controls pressure at the BH. So increasing the pressure in the BH relief (which you apparently have done) will not increase actual pressure at the BH if there is an upstream relief (FEL valve) that is set at 1500psi.

You mentioned that the FEL seems weak, even when the BH is not connected. Perhaps the FEL relief is set at 1500psi, which controls maximum pressure at both the FEL, the BH, and TPH (since all three are downstream of the relief). If that is the case, and you increase pressure at the FEL relief, that will increase pressure for both the FEL and BH. It will not affect the TPH because the end-of-the-line relief in the TPH will always limit the pressure at the TPH.

I am not sure I have seen what the pressure at the BH or FEL is supposed to be? Is it 1500psi?

 

[Surshot]

"Check the position of the 3 point hitch lever. I think I recall something about it having to be in a full up position or the loader will be 'weak'."

This could very well be the problem. With my L4400 if the 3-point lever is in the max position, up or down, the FEL will barely work. Move the lever off the max setting and the FEL works like Roscoe. Have no idea why but, it does this and the engine sound or pump sound changes quite a bit just moving the lever off max by one number. At max it sounds like it is in a strain.
Best,
Ed

 

[COMPRESSOR]

FARMERFORD,
I think your right,The BH is only going to be as strong as the relief valve setting on the loader.They do, the BH and the FEL feed off the same manifold,right.
That would be consistent to the weak loader.
I have to admit,I had to read your post three time to pound it though my head.
Farmerford,I can't wait to find the valve in the loader.Should however be alittle easier than the other one wherever it is?
THANKS ALOT FOR TAKING THE TIME TO RESPOND TO THIS POST.
THANKS TO ALL. COMPRESSOR!!!!!!!!!!!!!!!

.

 

[LBrown59]

"Check the position of the 3 point hitch lever. I think I recall something about it having to be in a full up position or the loader will be 'weak'."

This could very well be the problem. With my L4400 if the 3-point lever is in the max position, up or down, the FEL will barely work. Move the lever off the max setting and the FEL works like Roscoe. Have no idea why but, it does this and the engine sound or pump sound changes quite a bit just moving the lever off max by one number. At max it sounds like it is in a strain.
Best,
Ed

IF the 3 point lift lever on my BX23 is pulled fully back to the rear the FEL will not raise.

IF the 3 point lift lever on my BX1500 is pulled fully back to the rear The front blade will not raise.

The reason for this is the lever switches the hydraulic fluid flow back and forth between the 3 point hitch and any front mounted implement such as FEL Front blade Snow blower broom etc.

The Fel don't work because you shut off the supply of Hydraulic fluid to it by putting the lever in the wrong position.