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Thread: 580C low hydraulic pressure

  1. #1
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    580C low hydraulic pressure

    Finally got the old C where I could dig, and it just doesn't have enough a** on the backhoe. I'm trying to dig pine stumps, and this just won't do it. I've read the service manual on checks, and of course I don't have a flow meter, gauges or hand pump. Full of oil, new hyd filter. I'd like to have some insight as to how to proceed from some of the old timers if they will. I'm about convinced that it's the pump (machine is a 79), but would like to be able to verify before I spring for a new one. Hate to spend the money and it's still no good.

  2. #2
    Senior Member dwloop's Avatar
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    TheOldMan, I am sure the MelBen or Alrman will weigh in when they get the chance.

    Just a FYI I put togther a hydraulic pressure test gauge set for about $100 with hydraulic gauges I got from ebay and test quick connects and lines from hydracheck.com. They sell Stauff fittings and lines, a well known company for these fittings. On my 580b the manual states 2200 psi +/- 75 psi at full throttle with the main bypass open. This is with the hydraulic oil warmed. I would not replace pump or other parts without at least knowing this setting. My unit was a rental at one time (It still has the company stickers) and I think they turned the pressure down to save hoses, etc...

    I don't know if the 580c is the same open circuit system like the B, melben and alrman will know. If it is and yours cannot be set to obtain this pressure, then I would consider the pump. Outside of this setting I know there are secondary checks in the hoe valve bank that should be checked if the main setting is up to specs.

    If you want I can post the part numbers I ordered to get the lines and fittings I used.

    HTH
    Dave

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    dwloop - I really appreciate the comeback. I have the service manual, and it tells me how to check and set the Main relief valve, I'm gonna start there, I'll have to run to town tomorrow and get a couple of fittings. I just discovered that mine has a Danfoss pump. Parts manual says Cessna, TRW or Warner Motive, so guess someone has changed the pump. Don't know if this is even a compatible pump,but someone on here will know.

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    Senior Member dwloop's Avatar
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    No problem.. I agree, Danfoss doesn't sound right, but I haven't seen as many as some here.

    One more thought on digging stumps, many times it feels like you just don't have enough!! I have dug many stumps (50+) that were already cut on my property with my old B and with a newer rental 580SM. Even the newer Super M never felt like it had enough when dealing with that. I have to actually say that my older B does really well considering the age. I rented a smaller Kubota L48 several times a few years ago to do other work and got no where fast on the stumps.

    The stumps I deal with are mostly oak, hickory and elm, and they are buggers to get out. Digging stumps is tough on any machine unless it is a larger excavator. I have found that it takes a lot larger hole to get them loose than I would have thought several years ago when I started. I don't have any pines up here, so can't really relate to those. I know a good oak that is more than two feet across at the butt will take me a while and it is tough going, throw in a couple rocks the size of a pickup hood and you want to give up!! I take it as easy as I can to keep from tearing the ole girl up, patience and just keep going wider and deeper until I can get the root ball loose. If it is larger I will use the loader to flip it up out of the way, dig the hole deeper, then flip them upside down into the hole. Back fill and level it off...

    Dave
    Last edited by dwloop; 01-30-2012 at 06:40 PM.

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    The thing about pines, is they have many tap roots. Each horizontal root going out from the stump may have 2 or 3 huge taproots going down, and the main stump will have 1 - 3 that may be 20' long. You have to break all of this away before you can loosen the stump, then you have to get enought dirt away from the root ball to be able to lift the stump out of the hole. It takes a lot of hydraulic power to break the roots close to the stump. I dug the smaller ones with a Kubota that belongs to my neighbor, but stopped because I was going to break it. It had much more power on the hoe than this C.

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    As a long time owner of a 580 C I may have some ideas. The backhoe on a 580C is an attachment to the machine as many were also made as forklifts, trenchers, cable plows or LL for landscape loader. Point being the backhoe does not have a seperate relief valve and operates on the main relief near the loader controll valve. Cheking the main relief would be your first plan of attack. BE VERY CAUTIOUS! don't set the relief higher than specifications! Will give you all types of power to dig at a cost, The lift cylinders on the 580C work well in many situations but if you boost the pressure past specs, you will bend the rods at a considerable cost to repair (I had to learn this the hard way myself ) As for the Saur Danfos pump that is different. I don't see a problem as long as its not a load sensing pump but there were many different ones made. But the plumbing would have had to be radically changed to accomidate a load sensing pump so I doubt it. Guess all I realy wanted to say was I wouldn't run the pressures up past spec 2300 +- 50 psi. I have seen the main relief needle wear a grove in it that would acuse this problem as well, easily replaced (but if you dont set it to the correct pressure folowing instalation see previous statement) Hope this helps

    Dave

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    Senior Member alrman's Avatar
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    TheOldMan, if you have a manual you should adjust the main relief pretty easily - I'm sure you will, but, let us know what happens.
    To steal ideas from one person is plagiarism. To steal from many is research

    Have you updated your user profile yet?

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    I just rigged up a 5000psi gauge and connected to the 1/4" plug on the loader valve. Reads approx 2050# @ 1500 rpm. Adjusted the screw in as far as I could and still get the acorn nut back on, pressure didn't change. I'm sure the oil wasn't as hot as it should be, I held the loader back agains the stops for 15 second intervals with 15 second rests in between about 10 times, but no pressure changes wer noticed. About 1500 is all the engine will turn with the loader control all the way back. I would think that if the power beyond fitting was leaking it wouldn't affect this setting - or would it? Don't have any idea where to get my hands on a flow meter. Is a new pump next?

  9. #9
    Senior Member dwloop's Avatar
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    TheOldMan, what was the engine RPM at no load?? Was it the rated 2250 and then dropped to 1500 RPM when holding the loader curl back??

    Dave

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    yeah, that's about right. It turns very easily over 2200 with no load. What really puzzles me here, is I picked up an absolutely full bucket of sand w/loader just fine.

  11. #11
    Senior Member alrman's Avatar
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    A hydraulic stall at 1500rpm without full hyd. pressure - only 2050psi............ the fact the pressure wont rise with valve adjustment indicates a bad pump.
    BUT, the engine shoudn't drop that much. How much smoke is coming out while under load? Does it have clean fuel filters / good supply of fuel / clean air filter?
    If the hydraulic could make it to 2300psi - the engine would near stop......
    That extra 200 psi will make a big difference in digging power - will probably sort out a few more old hoses too.
    To steal ideas from one person is plagiarism. To steal from many is research

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    Senior Member dwloop's Avatar
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    Alrman, if one of these 188 diesels were in really good shape with a good hydraulic pump, what RPM should they pull down to @full thottle, @2200 PSI on the main relief?? Curious about my 580B as well...

    Thanks,
    Dave

  13. #13
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    You know, I never really paid that nuch attention to rpms. It's pulling hard with the loader held tight against the stops in both elevation and roll back. Doesn't seem to be smoking in excess to me. I've changed all the filters except fuel, hadn't done that yet, because i hate the air bleeding to get it running again. Runs so nice now, I hate to fool with it. By the way, this is a C, so the engine is a 207. Don't think that makes any diffeence. I'm waiting for airman to come back with some more advice. Pretty sure the pump is the culprit, but I want to see what he has to say. If I could find any numbers on the Danfoss pump, I'd see what it is supposed to be. Don't find any.

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    Oldman are you running the Case Hy Tran Ultra hydraulic oil in the machine? also will the hoe lift the rear end of the machine easily?

  15. #15
    Senior Member alrman's Avatar
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    Quote Originally Posted by dwloop View Post
    Alrman, if one of these 188 diesels were in really good shape with a good hydraulic pump, what RPM should they pull down to @full thottle, @2200 PSI on the main relief?? Curious about my 580B as well...

    Thanks,
    Dave
    Well, even service manual does not give stall specs. But an educated guess would say it should only drop about 200rpm. So, if no load full rpm is 2300 should only drop to about 2100rpm.
    To steal ideas from one person is plagiarism. To steal from many is research

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