fordson 713 backhoe hydreco relief valve adjustment

[jacob]

I'm new to this site, owning a tractor and working on hydraulic systems. I just picked up a super major with a 713 backhoe on it, and I'm of the opinion that it has issues with the pressure relief adjustment. The loader works like a charm, and shares the same pump. All the hydraulic lines are new, and PO claims to have rebuild the valve assembly.
It was low on hydraulic fluid. I remedied this and tried to bleed out any and all air in the system. It still cut out when any pressure is applied. WIll dig, but has to be babied to get any real digging on loose soil with the 2' bucket.
If I remove the cover to the valve assembly, will the adjustment screws be obvious, one for each control I assume? Or is the boom, swing, stabilizers, etc all adjusted from one relief valve.
Everything else works like a charm, and the tractor seems very strong. There is fluid leaking out of disc brake housings. Should that concern me at this point?
Is there a pressure test kit that anyone recommends that has the right adapters to be of use on this tractor?
Thanks for any and all help. I apologize for being a newbie, I tried first to find answers on other threads but really came up empty handed.

[Dandy Dave]

Sounds to me like the pressure relief valve spring is weak or broken. Take the BH relief valve apart to check it. This is not the first time I have run into this problem on hydraulic back hoes. Dandy Dave!

[jacob]

On the left hand side of the backhoe (from sitting in the seat), there is a large locknut (over an inch). This has a allen headed threaded rod.
Is this where I will find the pressure relief valve? Is it one valve for the whole backhoe attachment, or is there a valve for every function.
I don't have a manual for this thing yet. I'm hoping the valve and spring are still available if they are shot.
Thanks!

[Dandy Dave]

Photos would help. Usually there will be just one relief valve for the backhoe unit. It sounds like you have found it. You should beable to get some sort of a repacement from a hydraulic rebuilder and supply shop if yours is weak or broken. Take it apart and see what the spring looks like. Just be sure to get it back in the same place when you put it back together. It also may have some trash under the seat that is keeping the valve partly open. The only way to find out is to take it apart. Dandy Dave!

[jacob]

Thanks Dave!
What I found was a clean, crisp new looking spring valve and seat.
After mild adjustment, the hissing fluid sound moved to the loader control assembly, (is this called a spool assembly also?). I followed the lines. The pump feeds the loader valves first, and the backhoe is taken off of the loader valve assembly. There is what appears to be a relief valve here also, but it is not screw adjustable. I'm wondering if I can put a shim between the threaded cap and the spring and get any results from this? It definitely is audibly bypassing at this junction, and the loader and hoe are piped out of it.
I'm thinking of trying this tomorrow, as well as picking up a guage and trying to test and set the pressure, assuming it can get up to pressure.....

[Dandy Dave]

It is possible that the loader valve is popping off first, and that spring is weak or broken. I agree with getting a pressure gage to be sure that have the right pressure when the relief valves unload. I've seen washers under springs before even from the factory on different applications. Maybe someone has had it apart in the past and lost one or two of them? Some relief valves have a second valve and spring inside of the adjuster housing also.

The valve spools are the parts inside the valve body that the control handles attach to. On a backhoe, they are the double acting type. Dandy Dave!

[jacob]

This is the loader valve that seems to be letting loose:
(Hydraulic Relief Valve - For Models: 2000, 3000, 4000, 5000, 6000 (1965-1975). This valve is for piston or gear type in center housing. (Part No: C7NN638E)). I found it on this site, it appears to be the same. (http://www.ytmag.com/cgi-bin/store/sear ... lic+System.)
I'm wondering if it is piped in wrong. I can't find any specs on this relief valve as to when it releases, and it does not seem to have any form of adjustment. It seems to be set perfectly for the loader. It looks new. Not that that means anything...

Is there another way to pipe from the pump to the backhoe? It seems like two pressure relief valves might be overly redundant anyway. I took some photos but haven't figured out how to post them yet.

Thanks!

[Dandy Dave]

This backhoe has not been on this tractor all along??? Or has been been re-piped before your purchase??? You could put a Deverter Valve in the line that feeds the loader, feed the loader off of one out line, and the backhoe off of the other. It is a simlple push and pull valve that feeds either the backhoe, or the loader, but neither at the same time. As long as each unit that you want to run has its own relief valve like you have it will work fine. Dandy Dave!

[Dandy Dave]

Here's a valve that gives you a general idea....

http://www.amazon.com/dp/B005H3U67C/?ta ... B005H3U67C

[jacob]

Thanks Dave!
I don't know the history on the machine, but it appears to be a factory made and possibly installed 713 backhoe and I don't know what # loader. PO had redone all, almost all, of the hydraulic hoses as well as rebuilding the spool valve for the backhoe. The left stabilizer won't stay up, maybe that is a bad sign for the rest of the rebuild. Every ten seconds of moving forward you have to pull the stabilizer lever...
I like the idea of the switch, to feed one or the other implement.
My backhoe is piped from the loader spool valve, into a port labeled out.
Would it make more sense to remove and replace the original loader spool valve? I can't seem to find parts for it, or anything regarding what it is. I see the same one in many thread postings on majors, etc.
The relief valve is not adjustable, though I imagine I could take it to a machine shop and have the back cut open and replaced with a threaded plug so I could adjust the tension on the spring. Probably a dumb idea, pushing the obsolete further into the future?
-

[super6954]

Thanks Dave!
I don't know the history on the machine, but it appears to be a factory made and possibly installed 713 backhoe and I don't know what # loader. PO had redone all, almost all, of the hydraulic hoses as well as rebuilding the spool valve for the backhoe. The left stabilizer won't stay up, maybe that is a bad sign for the rest of the rebuild. Every ten seconds of moving forward you have to pull the stabilizer lever...
I like the idea of the switch, to feed one or the other implement.
My backhoe is piped from the loader spool valve, into a port labeled out.
Would it make more sense to remove and replace the original loader spool valve? I can't seem to find parts for it, or anything regarding what it is. I see the same one in many thread postings on majors, etc.
The relief valve is not adjustable, though I imagine I could take it to a machine shop and have the back cut open and replaced with a threaded plug so I could adjust the tension on the spring. Probably a dumb idea, pushing the obsolete further into the future?
-

Hi
sounds like you are having fun with your project, the stabilizer dropping could be the control spool leaking, or an internal leak between the the 2 sides of the cylinder as it is double acting to pull the stabilizer up or push it down to lift the machine . can you also see an external leak on the outside of the cylinder where the rod comes out as it could also leak oil out the end and cause the drop.
I just re read your post and saw that you think the rear is piped from the front out to the out port on the back, it should be pressure in on front block from pump then from out on front to in on back and out on back should run free back to tank and I guess there is hopefully a filter in there someplace too , I wonder if the oil coming in the back block the wrong way is affecting the front or back block some how . ive never had blocks connected wrong like that before in my 20 odd year career so don't know for shaw maybe Dave does

Regards Robert

[jacob]

Oh, no, it is piped from the out on the loader spool to the in on the backhoe. I checked, it is the 712 fordson loader and 713 backhoe. The spool valve is original. Can't find the relief valve replacement anywhere online anyway. It is not adjustable.
I'm guessing if I can't find it anywhere I have to get a new spool valve or have the nonadjustable relief valve machined to be adjustable?
I hope to be having fun with it once it can dig!
-J

[Dandy Dave]

Yes, the dropping stablizer is most likely the internal packing in the cylinder. Also, sometimes I have taken a cylinder apart to find that the nut that retains the piston has loosend and the oil is leaking between these parts.

Changing the loader valve may be the way to go. Be sure that the replacment that you get can be set to the pressure that you need. Dandy Dave!