Getting tired of hydraulics- Another help needed thread

[futuresweets10]

I had the valve assembly for the FEL of my backhoe "rebuilt" at a local shop. I told them to go through everything on it and replace every part that was replaceable and inspect everything else. Got the valve assembly back and installed it and the FEL bucket still wont work right. I assumed it had to be the cylinder, but after testing there is nothing wrong with the cylinder.

If I pick the FEL arm up the bucket falls all the way down to the lowest point. I had assumed it was by passing, but I played with it for about an hour today. If i set the bucket down flat on the ground and try to tilt the bucket down it will tilt down and lift the front of the machine like it is suppose to do. Once I do that I can tilt the bucket back up and it will tilt until its flat. It only tilts up until its flat and no further. Its obvious that the retract function (tilt bucket down) works, but the extend function of the cylinder does not work.

I obviously dont have a problem with a cylinder or valve by passing because that would be all the time (even when the bucket was on the ground). Right? The shaft end of the cylinder is getting fluid when I push the stick to the left and its letting the fluid back out when I push to the right. However, when I push to the right it isnt sending pressure to the butt end of the cylinder. Doesnt this have to be a valve problem? Any ideas what it could be so I can have knowledge when i go back to the shop and complain that they didnt do something right?
HELP!!!

 

[AKKAMAAN]

are there any inline valves between control valve and cylinder?
are there any work port valves on/inside the control valve?

 

[futuresweets10]

are there any inline valves between control valve and cylinder?
are there any work port valves on the control valve?

Straight line between control valve and cylinder
Not too sure what is meant by work port valves... Tried to google it, but couldnt find anything.

I would assume it does have them being that it has everything else known to man on it....

On another note... When i push the stick to try to get the bucket to curl up I hear a hissing sound comming from the valve assembly.... Almost sounds like what a fluid spray (leak) would sound like, but no leak

 

[AKKAMAAN]

Straight line between control valve and cylinder
Not too sure what is meant by work port valves... Tried to google it, but couldnt find anything.

I would assume it does have them being that it has everything else known to man on it....

Work port valves are built into to the control valve housing, either on the bottom of the valve (under the spools) or just by the work port (where hoses are connected). I assume there is a work port relief valve for the bucket....or eventually an inline valve.....follow hoses from cylinder back to control valve to check if there is any thing plumbed in between.....

You had that previous "crashed" pump, so expect some metal debris cruising around in the system...probably something is holding a work port relief valve a little open so flow by passes

 

[futuresweets10]

Work port valves are built into to the control valve housing, either on the bottom of the valve (under the spools) or just by the work port (where hoses are connected). I assume there is a work port relief valve for the bucket....or eventually an inline valve.....follow hoses from cylinder back to control valve to check if there is any thing plumbed in between.....

You had that previous "crashed" pump, so expect some metal debris cruising around in the system...probably something is holding a work port relief valve a little open so flow by passes

I already checked and there are no other valves in line between the cylinder and valve assembly.

Can you tell by these pics if there is work port valve on the assembly? If so, can you point out what it is?

 

[David Devuono]

Interesting problem. Let us know the kind of tractor, if it came on suddenly or slowly started acting up. Age, hours on tractor. Did they say they found anything with the control valve? How long have you owned the tractor? Do you have to select between Loader and 3pth? You described hearing a hissing sound, was the bucket or arms dropping when you heard the hissing. I am not sure how much room you have to play with hoses, but if the FEL arms go up and down normal, could you not switch the working ports and see if the curl now works and the lift starts acting up?

If you where to put the tip of the bucket on a stump, and curl the bucket back (it was only curling to level position) and at the same time push down with the lift arms will the bucket curl back. If not, it may be seizing. With the tractor shut off and someone curling the bucket back, can you manually tilt the bucket back?

I like to isolate things, while its messy, you could even use compressed air to operate the cylinder with hoses disconnected, ensure you can force the bucket cylinders through their full range of motion. Good Luck

 

[David Devuono]

My valve only has an inlet, outlet and the four work ports. Hopefully the experts can help you on that contraption

 

[futuresweets10]

Its a cat 416b back hoe

 

[AKKAMAAN]

I already checked and there are no other valves in line between the cylinder and valve assembly.

Can you tell by these pics if there is work port valve on the assembly? If so, can you point out what it is?

 

[futuresweets10]

I already checked and there are no other valves in line between the cylinder and valve assembly.

Can you tell by these pics if there is work port valve on the assembly? If so, can you point out what it is?

Well, Now that we have established that I do have work port valves, whats the next step? Could these have a problem, or could they need adjusted?

If I have access to them, can I just unscrew the work port valve from the valve body and remove it to inspect it, or are there small parts like springs and other things that will fall out if I unscrew it?

 

[AKKAMAAN]

Well, Now that we have established that I do have work port valves, whats the next step? Could these have a problem, or could they need adjusted?

If I have access to them, can I just unscrew the work port valve from the valve body and remove it to inspect it, or are there small parts like springs and other things that will fall out if I unscrew it?

yes just take them apart and clean...expect springs and washers, but i think the relief valves will come out as cartridges...the other two with just a hex cap is probo
is probably just load check valves...spring and a poppet..

 

[xrjohndeere]

Just a suggestion. Do you have the hoses hooked to the wrong ports. I hooked the old loader off my older johndeere tractor to my new one and went by the colors. They were wrong. The loader acted the same way you are describing. After I hooked the hose up to the correct ports it worked fine. I thought that if you just put a hose in the wrong port it would just function reverse of what it should, but that was not the case. Hope this helps.

 

[AKKAMAAN]

This is what you can expect coming out....MY PICTURE SHOWS ANOTHER VALVE, but still shows how theses valve are attached to the work port....


You might have use for a narrow magnet "picker-upper", to get the check valve poppet to come out..

 

[futuresweets10]

So in theory I can take the secondary out and it should be self contained. All small parts that can fall out will be inside of it?

 

[AKKAMAAN]

So in theory I can take the secondary out and it should be self contained. All small parts that can fall out will be inside of it?

....IF it really is a cartridge valve, which I think it is....only the load check vale spring and poppet should be separated from the cartridge....put the wrench on the inside largest hex....stay organized...check the order it comes out, and put it back together the same way...You are in good shape if the valve is disconnected from the tractor...but it is well do-able on the tractor too...

 

[futuresweets10]

....IF it really is a cartridge valve, which I think it is....only the load check vale spring and poppet should be separated from the cartridge....put the wrench on the inside largest hex....stay organized...check the order it comes out, and put it back together the same way...You are in good shape if the valve is disconnected from the tractor...but it is well do-able on the tractor too...

Valve assembly is back on the machine which is what pisses me off the most... I paid a shop to re-do everything on the valves and I had countless hours in removing the valves and re-installing.... And now I have to go back and do what I paid them to do with the **** thing on the machine.

 

[wdchyd]

Valve assembly is back on the machine which is what pisses me off the most... I paid a shop to re-do everything on the valves and I had countless hours in removing the valves and re-installing.... And now I have to go back and do what I paid them to do with the **** thing on the machine.

Another good reason to troubleshoot with gauges rather than "Eyeball Detective", at least you'll have pressure readings before and after you take it apart and it'll give you good exposure to proper troubleshooting techniques ....Could this be Deja Vu or am I imagining this has been suggested before????:confused2:

 

[futuresweets10]

Another good reason to troubleshoot with guages rather than "Eyeball Detective", at least you'll have pressure readings before and after you take it apart and it'll give you good exposure to proper troubleshooting techniques ....Could this be Deja Vu or am I imagining this has been suggested before????:confused2:

I did get a gauge and I have been using it some. Im no expert on this and dont really know what I would be looking for testing with this problem using a gauge. I could put a gauge on the line going to the cylinder, but I already know its not getting pressure, so thats not going to tell me why it isnt. Not argueing with you, just not experienced enough to know how.... BTW, I might not be able to use a gauge, but I can spell it right...:laughing: (sorry, I had to)

 

[wdchyd]

Take the hoses off tilt cyl and attach gauge to end of hose where it hooks up to cyl....deadhead it up to pressure....it should read what the PRV is set at..and it should hold pressure when spool is returned to neutral....check both sides....(if you have only 1 gauge then do them separately)....if they go up and hold then your problem is not your control valve....then repack hyd cyl....if no pressure or is not holding then keep digging in that DCV....

 

[futuresweets10]

Take the hoses off tilt cyl and attach gauge to end of hose where it hooks up to cyl....deadhead it up to pressure....it should read what the PRV is set at..and it should hold pressure when spool is returned to neutral....check both sides....(if you have only 1 gauge then do them separately)....if they go up and hold then your problem is not your control valve....then repack hyd cyl....if no pressure or is not holding then keep digging in that DCV....

The way its acting makes it impossible to be the cylinder. Its leaking down on one side only, that means its not bypassing. The only way it could be the cylinder is if it were leaking externally, but its not.