New Valve Body or ??

[cycle_gator]

I have a 1968 Case 580 CK with a model 33 backhoe. While I would like to think I can stop that hydraulic fluid from leaking around the tops of the spools by replacing the O rings, I think I know that would be futile. About half of them are leaking whenever the pump is running. So, the question, what to do? The pump produces 25 GPM. There appear to be some suitable replacements out on the market, but that means fiddling with the mount and all those hoses. Question, what to do?
1. Try to find original Case valve sections for those that are leaking the worst and replace those sections? I saw somewhere where a person looked into the cost of buying all the seals for a full valve rebuild and the cost was around $800, not to mention trying to find and buy the sections.
2. Try to find another model 33 with a better valve body than mine and buy it, mix and match parts
3. Purchase a non-Case valve body and make it fit. I am wondering how much slack I have in terms of pump capacity versus valve flow rate. For example would a 15 to 20 GPM valve stack work? For instance Surplus Center has a Walvoil Valve
6 SPOOL 16 GPM WALVOIL JOYSTICK BACKHOE HYD VALVE
or Muncie makes 40 GPM stack valves -- 60V series, not sure about cost, but likely not an inexpensive option
4. Replace the O rings and close my eyes to the inevitable leaks?

The machine is in decent shape, 188 diesel that runs really well, front loader is fine, needs new rear tires, not a great deal of slop in hoe or bucket and I got it for a decent price.

Advice?

Thanks in advance.

 

[J_J]

Do you use the full 21 GPM now for the flow into the BH?

GPM = speed of operation.

Since is is almost impossible to reseal a used valve, I think I would invest in another BH valve with less flow capacity.

On the valve you posted, I did notice something strange about the relief settings.

Although the valve is rated up to 4600 psi. the relief is only rated to 900 to 1400 psi. Something wrong with that. Maybe typo.

 

[cycle_gator]

JJ

Thanks for the advice. I am not sure what the flow into the backhoe is. System is open center. Flow goes from pump to FEL, PB to BH and tank. I think the work ports are SAE 10 and the in/out ports are SAE 12. I also noticed this valve with load checks and option for work port relief.

6 SPOOL 20 SERIES PRINCE STACK VALVE POWER BEYOND

rated for 20 gpm.

I suspect you would advise me to find a flow meter and see what is going into the backhoe. It is not broke at this point, just leaking, so it is not something I need to order tomorrow.

Thanks again.

 

[CalG]

It would be nice if your valve were built like this one
http://www.tractorbynet.com/forums/parts-repairs/143876-bobcat-753-hydraulic-control-valve.html
at least you could replace o-rings ;-)

But.

Perhaps there are valve rebuilders that would "respool" your present valve for about the same money as the "lesser replacement".

But
If you went with a lower flow unit, think of the control you would have. Folks around would be calling you the "Back Hoe with the velvet touch" ;-)

 

[J_J]

You should know that most hyd valves are not rebuildable.

Spools are a precision fit to a particular valve, and they do not make replacement spools for repair. They do make new spools for new valves, but they are facturer replaced.

Why would you put a new spool in a worn bore anyway.

In a stacked valve, you can replace the o-rings between the stacks and have a good functional valve.

The spools that have o-rings on the spools, the o-rings are there to keep debris out.

If the spools are weeping fluid, o-rings might help some. If you have something like a 5 drops per minute from a spool, there is no fixing that. You either live with it or get a new valve.

Even though you have a 10 micron filter in the hyd system, it is the particles smaller than 10 micron that help wear the spools and bore until the fluid is not contained anymore.

If one was really smart, they would install a 1 micron as a bypass filter in the system. Overtime, all the fluid will pass through the 1 micron filter.

An example of the 1 micron bypass filter.

On one of my Dixie Choppers with a Kohler engine, I had a 1 micron bypass filter along with a 10 micron filter, and when the engine was torn down many years later, the tech said the engine was as clean as a new engine. 1 micron is really small. 0.000039 inch

 

[cycle_gator]

Judging by the condition of the fuel and oil filters (this is a new to me machine) I would be surprised if the current hydraulic filter is either present, or even filtering 10 microns. The machine has about 6000 hours on it and not completely easy hours, either. I do know that the spool O rings were replaced once by the first owner (I am the third owner) which tells me the valve stack has needed attention for a number of years. I think it is time to renew the whole thing and then protect what is likely a much less robustly built valve with filtering that JJ suggests, standard 10 micron filter in the can and a 1 micron bypass filter on the side. Thanks again for the advice. While I am always tempted to go the cheap way, I also know that I would prefer to put in a solution that will not require continual attention.

 

[CalG]

Judging by the condition of the fuel and oil filters (this is a new to me machine) I would be surprised if the current hydraulic filter is either present, or even filtering 10 microns. The machine has about 6000 hours on it and not completely easy hours, either. I do know that the spool O rings were replaced once by the first owner (I am the third owner) which tells me the valve stack has needed attention for a number of years. I think it is time to renew the whole thing and then protect what is likely a much less robustly built valve with filtering that JJ suggests, standard 10 micron filter in the can and a 1 micron bypass filter on the side. Thanks again for the advice. While I am always tempted to go the cheap way, I also know that I would prefer to put in a solution that will not require continual attention.

This "valve repair" story has a happy ending...
http://www.mytractorforum.com/showthread.php?t=88538