B7200HST hydraulic issue

[Driver57]

Two part question.

I have an ‘84 B7200HST.

First part-

I have around 450 of ballast on the 3 point. When I set the 3 point about a foot off the ground, the loader will start to lift when I push the loader control valve to the float position. Obviously the loader and 3 point are operated with two different levers, so what would cause this and what would the remedy be?

Next part-

When I bought it 6 years ago I had to replace the loader control valve as the original one had failed Ang vise grips were used to control the roll.
The Kubota OEM valve was a bit too pricey so I purchased a prince 8gpm two spool valve. I’ve never been happy with its performance, as it is very jerky compared to the original valve. Is the less than smooth operation attributed to an inexpensive valve? If so, can anyone recommend a valve that’s smoother but not as pricey as the Kubota?

Thanks in advance,
Mike

 

[DustyRusty]

There is a reason that Kubota OEM parts are expensive. This is because they are specifically designed for a specific tractor. You spent money to purchase a substitute valve, and now you are willing to spend more money on another substitute valve. If you add the two dollar amounts you most likely will be close to what an original valve costs. In life we all make choices, and we all have to live with our choices in life. If I were buying a can of peaches, I might try the less expensive store brand vs. the more expensive nationally known brand. When I buy tires I always buy a nationally known brand rather than a lesser-known brand that is less money. In the end, the more expensive national brand of tires will last longer and will cost less over the life of the tires.
I would bet that you purchased a Kubota because of its reputation of quality rather than another band of tractors that is the same color but doesn't enjoy the same reputation. What I find most confusing is why people will look for the least expensive replacement part when it comes time for service. I often wonder if these very same people choose their health care the same way. Need surgery, go to Mexico when the surgery costs less, but is the outcome the same? I don't know the answer, but I will bet that the outcome would be better in the USA than it would be in Mexico for the average person.

 

[Driver57]

So what you’re saying is I’ve been victimized by my own frugality. Fair enough. Will look into purchasing a Kubota valve. Just didn’t know that having a load on the 3 point would affect loader operation.
Thank you for your response and opinion.

 

[DustyRusty]

So what you’re saying is I’ve been victimized by my own frugality. Fair enough. Will look into purchasing a Kubota valve. Just didn’t know that having a load on the 3 point would affect loader operation.
Thank you for your response and opinion.

I don't know if that is specifically the problem. I do know that I had a Kubota rear remote valve that had failed effected my 3-point hitch to the point that it wouldn't lift. I don't remember if it also affected my loader valve because that was about 5 years ago. I am certain that one of the more knowledgeable people will chime in with additional information. I was only pointing out the obvious when you said that you were unhappy with the replacement loader valve compared to the original Kubota valve. Do you still have the original valve? Might it be repairable by someone who knows how to repair a valve? My valve wasn't repairable since Kubota had run out of service parts and said parts were no longer available.

 

[North Idaho Wolfman]

How many hoses come off the Loader valve?

And does the tractor whine like the it's still trying to lift the three point?

Try it with the three point at max height.

 

[Driver57]

How many hoses come off the Loader valve?

And does the tractor whine like the it's still trying to lift the three point?

Try it with the three point at max height.

How many hoses come off the Loader valve?

And does the tractor whine like the it's still trying to lift the three point?

Try it with the three point at max height.

There are four lines coming off the loader valve. Two coming in from the hydraulic pump.
I will try putting the three point at max height and see if that makes any difference. However I also noticed when I move the three point under load I get a bit of movement in the loader.

 

[Driver57]

How many hoses come off the Loader valve?

And does the tractor whine like the it's still trying to lift the three point?

Try it with the three point at max height.

I don't know if that is specifically the problem. I do know that I had a Kubota rear remote valve that had failed effected my 3-point hitch to the point that it wouldn't lift. I don't remember if it also affected my loader valve because that was about 5 years ago. I am certain that one of the more knowledgeable people will chime in with additional information. I was only pointing out the obvious when you said that you were unhappy with the replacement loader valve compared to the original Kubota valve. Do you still have the original valve? Might it be repairable by someone who knows how to repair a valve? My valve wasn't repairable since Kubota had run out of service parts and said parts were no longer available.

The original valve was not repairable due to where the it failed. I’m pretty sure I threw it away as there Was no reason to keep it.

 

[Driver57]

Original valve.

 

[North Idaho Wolfman]

There are four lines coming off the loader valve. Two coming in from the hydraulic pump.
I will try putting the three point at max height and see if that makes any difference. However I also noticed when I move the three point under load I get a bit of movement in the loader.

Not having a tank line (third line) is part of the reason you're dealing with a jerky and unpredictable loader and three point control.
New valves need Power in, Power beyond, and Tank to work properly.

You can't buy an OEM valve they are long obsolete and most newer valves are better.

One other reason that loader controls can be jerky is if the valves are over sized, you want a valve as close to 5 GPM as you can get.
If you use a 13 GPM valve you loose finer control, as you do with a cheap valve too.

 

[Driver57]

I’ve looked everywhere I know for new or used Kubota valves. Also it’s a Woods loader.
Any recommendations for a better quality valve? The 7200 total hydraulic flow is only 4 gpm.

 

[TheOldHokie]

I’ve looked everywhere I know for new or used Kubota valves. Also it’s a Woods loader.
Any recommendations for a better quality valve? The 7200 total hydraulic flow is only 4 gpm.

Your Prince valve is fine. The problem is improper plumbing of the loader valve. You need to convert that valve to power beyond and add a tank return line.

That particular Prince Wolverine valve is a little different than most. To convert it to power beyond you install a 1/4" BSPT pipe plug INSIDE the power beyond port. The plug normally ships with the valve but it is about the size of a peanut so its easy to lose. Replacements are cheap - about $5..

EDIT: Here is a link to the power beyond plug from Surplus Center.

Power Beyond & Closed Center Plug 8 GPM MB Valves Wolverine by Prince Mfg 671900122 | Valve Parts & Accessories | Hydraulic Valves | Hydraulics | www.surpluscenter.com

Power Beyond & Closed Center Plug 8 GPM MB Valves Wolverine by Prince Mfg 671900122, Valve Parts & Accessories, P-BEYOND & CLOSED CENTER PLUG 8 GPM MBPrince Mfg,671900122 ,

www.surpluscenter.com

Dan

 

[Driver57]

Your Prince valve is fine. The problem is improper plumbing of the loader valve. You need to convert that valve to power beyond and add a tank return line.

That particular Prince Wolverine valve is a little different than most. To convert it to power beyond you install a 1/4" BSPT pipe plug INSIDE the power beyond port. The plug normally ships with the valve but it is about the size of a peanut so its easy to lose. Replacements are cheap - about $5..

EDIT: Here is a link to the power beyond plug from Surplus Center.

Power Beyond & Closed Center Plug 8 GPM MB Valves Wolverine by Prince Mfg 671900122 | Valve Parts & Accessories | Hydraulic Valves | Hydraulics | www.surpluscenter.com

Power Beyond & Closed Center Plug 8 GPM MB Valves Wolverine by Prince Mfg 671900122, Valve Parts & Accessories, P-BEYOND & CLOSED CENTER PLUG 8 GPM MBPrince Mfg,671900122 ,

www.surpluscenter.com

Dan

Thanks Dan and everyone else for the input. Will order the plug.

 

[Russell King]

You will need to get another hose and some fittings also since now you have power beyond and tank return as I understand what you’re doing. You can also order them if you want to

 

[Driver57]

What would be the difference between the old control valve and the Prince valve I have now?
I thought all hydraulic systems needed a holding tank, with the transmission serving this need.
Would it just be less headache to order a valve like the old one?

 

[TheOldHokie]

What would be the difference between the old control valve and the Prince valve I have now?
I thought all hydraulic systems needed a holding tank, with the transmission serving this need.
Would it just be less headache to order a valve like the old one?

NO - buying a different valve will not fix your problems.

Your Prince valve is exactly what you need but needs to be properly plumbed to work in your application. Here is a diagram taken from the instructions for your Prince valve.

1. Remove the steel plug that is currently in the C port on the valve and install the power beyond plug. I have circled it in red - - it goes inside the C port cavity.
2. Once the power beyond plug is installed connect the C port on the loader valve to the return port on the tractor hydraulic outlet block. That is where you currently have the Tank port hose connected.
3. Now connect the Tank port hose on the loader valve to the oil filler on the top of the transmission. This is the low pressure return to tank.

That is official factory plumbing as used on the Kubota B1630 OEM loaders. I will post a picture later of the OEM tank return line on my B7200 to help make this a little clearer.

 

[Driver57]

I now understand. Thank you Hokie.

 

[Russell King]

The tank return is low pressure and can be connected to any available port that is above the fluid level in the transmission. The only problem may be that place is only the transmission fill port on the transmission. Most people use a tee fitting so they can still add fluid without having to remove the hose.

There may be other ports that can be used, for instance on my older L185 there was a port on to of the case back under the seat. See picture below and it is the one in the center that has two 45 degree fittings installed

 

[TheOldHokie]

The tank return is low pressure and can be connected to any available port that is above the fluid level in the transmission. The only problem may be that place is only the transmission fill port on the transmission. Most people use a tee fitting so they can still add fluid without having to remove the hose.

There may be other ports that can be used, for instance on my older L185 there was a port on to of the case back under the seat. See picture below and it is the one in the center that has two 45 degree fittings installed

View attachment 125817

The B7200 uses the transmission fill port and Kubota provided a special adapter for that purpose:

70050-01615

Messicks lists the adapter at $71 which is a bit pricey. I would probably roll my own. JFYI tank return port does not have to be above oil level.

Dan

 

[N3BP]

On the B7200, you're limited to the fill port. I've seen a post somewhere around here where someone fabricated one, so it is possible.

 

[TheOldHokie]

On the B7200, you're limited to the fill port. I've seen a post somewhere around here where someone fabricated one, so it is possible.

Its OEM but I am sure you could make your own. Here is a picture - it was originally a single line for the loader and I added a tee and second line when I installed the factory rear outlet option.

Dan