Great Bend 652 spooler Valve issue

[Yanmar1401D]

Appreciate any help! really new with this hydrualic thing but here it goes. I bought a 3pt backhoe for my tractor and taped into the existing hydraulics. I thought I had the high pressure / return lines correct but when I hooked it up to the backhoe needless to say I heard a pop an fluid started leaking out of the spool valve. I took apart the spool valves and saw that there were o-rings in between. Replaced all and put back together. Still leaking Can someone enlighten a green horn what happens when I hook it up backwards to the spool valve and also what else maybe leaking?. It is a slow leak that comes out the bolt holes right at the end of the stacked valves. Are all the spool valves ruined?

Help!!!

thank you

 

[Stonehaller]

I do not think you ruined the valves, but you probably have blown out some o-rings. There are o-rings on each end of the spool valves and there are also between the valve bodies in the stacks. The spool o-rings seal the low pressure end of the spool and are not intended to hold high pressure. Sounds like you replaced the o-rings between the valve bodies. You should pull the end caps of each valve and check/replace the o-rings on the spools.

 

[Yanmar1401D]

Thanks for the reply! I did change all the O-rings between the stacks and on the end caps. When you say spooler o-rings, is that on the top of the spool or the bottom? The leak is weird since the leak is coming out of the 2 bolt holes on the end cap. As if the oil was running down the end of the bolt. No oil from the top, back, bottom. Just out the 2 rear long bolts. When I took it apart, I did not see any ports. Do you think that the o-rings between are still leaking? When I replace the o-rings in between they were all fine, none broken.

appreciate the help

 

[Stonehaller]

I am not familiar with your exact valves, but there should be caps on each end of each individual valve in the stack. On one end the valve spool sticks out and connects to the cable or lever that controls the valve. On the other end there is usually springs under the cap to center the valve. There should be o-rings or seal packing around the spool on each end. They may be in a groove in the body and you might have to pull the spool out to get to them. The o-rings seal any oil that gets by the spool to bore clearance. If valves are leaking on either end then you probably blew out these o-rings.

See item 8 in the attached diagram.

 

[AKKAMAAN]

here is another picture...

The rest of the spool is designed, by tolerance, to allow a small amount of leakage, between the highly pressurized cores and the low pressure cores....just enough to lube the spool and secure spool from not binding....
this is a typical rating for spool leakage...

btw....3 c/c is about 0.18 cui.....thats the normal leakage per minute between to cores at a pressure difference of 1500psi....you cant even see a 3" bore cylinder drift from that low leakage....unless you watch it for 10+minutes...

 

[kennyd]

To answer your question properly, we need lots more info, like:

1. What tractor do you have?
2. Is the valve on the new backhoe Open Center or Closed Center?
3. What backhoe is it?
4. Exactly how did you plumb it?


I suspect it's plumbed wrong or the valve on the 'hoe is CC and blocking all flow from the pump.

 

[Yanmar1401D]

The tractor is a Yanmar 1401D. believe it is an 80's model (bought it used so not sure). The backhoe is a Great Bend 652.

How can I tell if it is open or closed center?

As far as hook up, I basically placed a T into the current lines. found out quickly that I need a diverter valve so I capped off the loader to work the backhoe. This is when I blew the spoolers since I had the lines hooked up backwards. I flipped the lines and the backhoe worked fine but now the spooler valve is now leaking.

as I mentiioned earlier, I repacked all the o-rings between the stacks but the valve is still leaking out the back 2 long bolts that is holding all the stacks together.

Thanks all for your feedback

 

[kennyd]

The tractor is a Yanmar 1401D. believe it is an 80's model (bought it used so not sure). The backhoe is a Great Bend 652.

How can I tell if it is open or closed center?

As far as hook up, I basically placed a T into the current lines. found out quickly that I need a diverter valve so I capped off the loader to work the backhoe. This is when I blew the spoolers since I had the lines hooked up backwards. I flipped the lines and the backhoe worked fine but now the spooler valve is now leaking.

as I mentiioned earlier, I repacked all the o-rings between the stacks but the valve is still leaking out the back 2 long bolts that is holding all the stacks together.

Thanks all for your feedback

You do not have it hooked up properly. You CANNOT Tee into high pressure oil lines. ALL valves MUST be added in series. Hydraulic fluid-like electricity will "take the path of least resistance" so that is why you had to "cap off the loader" to use the backhoe.

The easiest way to tell if a valve is OC or CC is with air pressure-but since you have oil in all the lines it's gonna be messy! Basically apply air to the IN port on the valve (or the hose you have connected to the IN port) and see if the air flows through the valve and comes out of the OUT port while the spools (levers) are in neutral. If you get air-it's OC and that is what you need. No air means its CC and will not work-and can damage things if it has not already.

My best suggestion is this: Put EVERYTHING back together the way it was, and see if you still have the leak-it's possible you pinched an O-ring while re-assembling it. There is an outside chance you cracked the valve. Then once that is fixed you can research how to properly add a new valve to your machine.

Oh, and you didn't use cast iron Home Cheapot/Lowe's plumbing fittings did you? They are only rated for 150psi (some are 300psi) and can blow up when used in hydraulic systems.

 

[Yanmar1401D]

Well I found out that I have a Open center system. I reassembled the spoolers and still have the same leak Are there any suggestions on how to determine which spooler is leaking? Very difficult to tell since the only place it is coming out of the heads of the 2 rear bolts that connect the stacks together. I found out that I have the Parker V20 spoolers. Do not know if that will help.

Thanks all.

 

[kennyd]

Well I found out that I have a Open center system. I reassembled the spoolers and still have the same leak Are there any suggestions on how to determine which spooler is leaking? Very difficult to tell since the only place it is coming out of the heads of the 2 rear bolts that connect the stacks together. I found out that I have the Parker V20 spoolers. Do not know if that will help.

Thanks all.

Did you do anything I suggested?