L785 dumping the bucket on its own

[muddy94chevy]

Hello all, hopefully you guys can help me. I just got my L785 running and functioning. It has the 70" bulk material bucket on it and after a few loads, the bucket just started drooping (uncurling might be a better way to say it) on its own. If you curl the bucket by pushing the pedal, it curls right back, but the second you let off the pedal, it starts uncurling again. Its a pretty swift dump, probably a second or two and its starting to dump material out of the bucket. I cleaned the hydraulic screen and changed both hydraulic filters, they seemed like they might have been trying to compete with me for age. I also removed the load check valve. Only one as they were really hard to remove, had to weld a nut on the slot head cap. I removed the outer most one as that seemed to be the bucket side. I did not know what I was looking for but it seemed alright. I do not see any leaking around the tilt cylinders ( I am not certain that would show if they were leaking internally) I also do not see any leaking around the control valve. Hydraulic oil level is good and all the other functions work. I can not test Aux hook ups though but I can hear it going in to relief when I move the handle both ways. Sorry for the long winded post and if anybody has any Ideas I would most certainly appreciate it. Thanks in advance.

 

[Tazza]

I'd suspect an internally leaking cylinder first. Some times the nut that holds the piston on can come loose and allow fluid to by-pass. Hopefully it's a simple fix like this.
I think you need to re-seal your cylinder(s) to be sure they are not to blame.

 

[muddy94chevy]

I'd suspect an internally leaking cylinder first. Some times the nut that holds the piston on can come loose and allow fluid to by-pass. Hopefully it's a simple fix like this.
I think you need to re-seal your cylinder(s) to be sure they are not to blame.

Ok thanks Tazza for the response. As I lurked around this site before I registered, I noticed you responded and always had great info. so I am glad you responded to mine. Is there an easy way for me to test my seals? The only reason for me questioning is that when I first scoop dirt it does not drop at all. It doesnt do it until maybe 10 trips later. After I pulled the load check valve I tried to pick up the back of the tractor and it held the back of my tractor up just fine. But I have not tried to move any more dirt yet because the ground is too thawed and I dont want to make a huge mess. Although I feel like my load check valve inspection did not fix my problem because I literally just took it out and went oh thats all this thing is and put it back in. Is it typical for seals to be ok with no load? as my bucket stays up just fine with nothing in it. I appreciate your responses though. Please keep em coming.

 

[Tazza]

Ok thanks Tazza for the response. As I lurked around this site before I registered, I noticed you responded and always had great info. so I am glad you responded to mine. Is there an easy way for me to test my seals? The only reason for me questioning is that when I first scoop dirt it does not drop at all. It doesnt do it until maybe 10 trips later. After I pulled the load check valve I tried to pick up the back of the tractor and it held the back of my tractor up just fine. But I have not tried to move any more dirt yet because the ground is too thawed and I dont want to make a huge mess. Although I feel like my load check valve inspection did not fix my problem because I literally just took it out and went oh thats all this thing is and put it back in. Is it typical for seals to be ok with no load? as my bucket stays up just fine with nothing in it. I appreciate your responses though. Please keep em coming.

Some people have used compressed air to see if they could hear the air by-passing the cylinder internally.
If your machine has only one tilt cylinder, one way is to get metal caps that suit the cylinder fittings and hose fittings. Cap the hoses off, and cap one of the tilt cylinder fittings so the other is open. Start that machine and lift the arms up and see if the cylinder moves on it's own.
As you say it takes time for the issue to show up, it could still be a cylinder seal, but could be something else too.
Were your load checks just poppets? An old machine i mine had those, but also had a relief on the circuit that had torn seals, something to inspect too. Ideally, when you remove these parts, you should replace the seals, as they get hard over time and will not always re-seal when installed again.

 

[muddy94chevy]

Some people have used compressed air to see if they could hear the air by-passing the cylinder internally.
If your machine has only one tilt cylinder, one way is to get metal caps that suit the cylinder fittings and hose fittings. Cap the hoses off, and cap one of the tilt cylinder fittings so the other is open. Start that machine and lift the arms up and see if the cylinder moves on it's own.
As you say it takes time for the issue to show up, it could still be a cylinder seal, but could be something else too.
Were your load checks just poppets? An old machine i mine had those, but also had a relief on the circuit that had torn seals, something to inspect too. Ideally, when you remove these parts, you should replace the seals, as they get hard over time and will not always re-seal when installed again.

I believe they were just poppets, not sure what a poppet is though. lol Mine just had a flat head plug, on the inside of the plug had a space for a spring to seat, then the spring and a cup looking thing that also had a space for the spring to go. There were no seals or anything. Like I said I was really hoping to pull that out and find some dried up seals, but it did not look like there could be much to go wrong in there. The cup was clean and in good shape and the spring still seemed strong. Yes my machine has 2 tilt cylinders. I did think about the pressure relief valve, but thought that since everything else is working ok on it that it must be good. From my understanding my machine only has one pressure relief valve? When I locate it I will pull that out and check. I think that will be easier for me to check as I never had a cylinder apart. I believe I would be fine rebuilding one though. Thanks again for responding

 

[muddy94chevy]

I believe they were just poppets, not sure what a poppet is though. lol Mine just had a flat head plug, on the inside of the plug had a space for a spring to seat, then the spring and a cup looking thing that also had a space for the spring to go. There were no seals or anything. Like I said I was really hoping to pull that out and find some dried up seals, but it did not look like there could be much to go wrong in there. The cup was clean and in good shape and the spring still seemed strong. Yes my machine has 2 tilt cylinders. I did think about the pressure relief valve, but thought that since everything else is working ok on it that it must be good. From my understanding my machine only has one pressure relief valve? When I locate it I will pull that out and check. I think that will be easier for me to check as I never had a cylinder apart. I believe I would be fine rebuilding one though. Thanks again for responding

Hey so I worked the skid steer a little more over the weekend and I noticed that when I release the boom lift pedal, the boom actually will lower an inch or two then stop, It is lifting kinda slow and kinda weak. I noticed if I slightly try to lift the boom, I can actually lower the boom all the way down. If I push the lift pedal a little more It will start to lift. I was using a grapple bucket with it and the grapple did not have a lot of squeeze power either. The bucket drift problem is a lot better with full rpm. Both hydraulic filters are brand new and the suction filter is very well cleaned. Hydraulic fluid is pretty much new as I had a big leak when I replaced the one hydraulic filter ( stupid design that seals on the edge of the filter) and then I blew a hydraulic line shortly after that. After those instances I think I added 15-20 gal. Around 10 gal for the first filter, then around 7-10 for the hose. I believe my problem lies in the control valve. But the pump also makes me suspect too. But my travel is strong and my 2 speed works fine. But my charge light periodically comes on. Mainly if I try to do too many things at once. Sometimes I could not curl and lift at the same time. Or I noticed that if I was full curl and would purposely try to curl more with a quick tap of the curl pedal, the light will come on for that quick second. What do you guys think of that? Sorry for the long post! I appreciate any help