Hey everyone I'm new here and have a question about my case I just bought. When I first fire it up she seems to be okay, good power for a 1979 580 but it seems the warmer she gets the slower she digs. And also a screaming noise coming from somewhere. I replaced the hydraulic pump and new filter and oil but still doing the same. It has a few leaks but nothing major, any help would be great! Thanks
Issue with hyd system First a little history, is this your first case backhoe and a first time running a backhoe?. A little info about your machine, does it have a 4x1 bucket on the front, does it have a extenda hoe on the rear dipper to allow it to dig deeper, does your return to dig work on the loader bucket ( when you dump the bucket can you move the loader bucket lever and the bucket returns on it's own to the dig position). The levers on the backhoe are they a two stick/ three stick with foot swing/ four stick with foot swing. When you said the pump was replaced did you or the person before you reset the main relief valve, filter and oil changed at that time. The noise your hearing could be a issue with the extenda hoe still holding pressure if your machine has one. The lever/pedal must return to the center position, if it works with a floor pedal make sure there is nothing keeping it engaged, mud/rags/trash. This goes the same for the 4x1 lever and the return to dig, they can all rob and slow the system down. A worn or faulty quick connect under the rear at the trans axle top side, could also cause a restriction of flow and noise issue. The load check O-rings under the circuit reliefs on the backhoe control valve will also cause poor performance while using the hoe and is not uncommon to find them broken or missing. If you have the means, open the battery box, you will see a tube/fitting with a end cap, some may have a 1/8 pipe plug installed in them, this is where you check you pressure for your main relief, 2300 +/- 50 psi at full rpm while slowly raising the loader up to full height and holding it there for a few seconds.
This is my first hoe but I have run one before although not a lot. The one I ran before was a 580, the same year I think the only difference is mine has the extdahoe and the one I ran didn't. Everything works on it as far as the loader and the hoe just the problem I was talking about. Its a 4 lever with foot pedals and all seems to be good there except the valve bank leaks a little. I changed the pump and filter myself, as far as resetting the relief and all I didn't know anything about that. I'm kinda learning as I go on this thing. I read on line somewhere about cleaning a screen that is somewhere between the pump and hydro tank but I can't find one. As i'm sure you know the hydro tank is in the frame on the 580c and all I see is a hose going into the frame on both sides. Unless its back by the rear somewhere. But nothing seems to be hanging up or anything just gets slow,weak,and noisy when it gets warm. I will get a gauge and look for that cap in the battery box,I thank you for the reply, you've given me more idea's to check out.
Install a pressure gage in the 1/4" pipe plug on the inlet from the pump to the loader valve and test as sheepfoot described but do both hoe and loader seperately. use the lowest rpm that it will stay running under full load. The pressures should be exactly the same for both hoe and loader, if the pressure varies front to back I would suspect a failed power beyond oring in the outlet fitting of the loader control. On a C the pressure test port is behind a popout plug on the cowling to the right and in front of where your right knee would be if seated looking ahead. You will need a gage with a short hose, many use a grease gun hose adapted to the gage and a 1/4 bushing to get to the test port size
Thanks for the help melben, I've located the fitting I just have to get the gauge to test it. I may have gotten lucky though my nephew knows a guy who works on heavy equipment I'm just waiting on a call back now. I live in the middle of nowhere and surrounded by farms and there is one guy that does the work for everyone,needless to say it would be a wile before he could get to me. Hopefully I hear from my nephews friend soon and get her running like it should.
Well I've not heard anything from the guy that was going to look at the 580 for me and now I've noticed something else odd. When I pull the boom up the bucket curls up by itself and the boom drifts to the right, anyone ever heard of that before?
I would replace all the load check plug o rings and backup rings. They are located under the circuit relief valves on the backhoe control valve. You need to get them from your case dealer. It takes around 2 hrs. to replace them once you pressure/ blow the crud and clean the valve. Do not have to remove the valve, relieve pressure, unscrew the circuit relief, once out remove the load check plug under it along with the spring and poppet. Replace the two backup rings and o ring and reinstall. You can make a poppet puller tool out of a bolt head grinded to fit the slot but most times a tool with a little hook/pliers will pull them loose.
Thanks for the help sheepfoot, I'll get on that as soon as I get the parts.