Neighbor has a case 580 c backhoe hydraulics are weak and very slow he says it sounds like it isn’t getting fluid to the pump he has recently installed a new pump which didn’t improve the issue I’ve looked through the parts manual that he has looking at all the suction lines and don’t see a filter or screen in the suction lines any where no obvious leaks on the suction line I was wondering if maybe there would be a main relief valve somewhere that would be stuck causing his problems I’m thinking what he is hearing is the relief bypassing looking through the manual I can’t tell where the relief would be
The main relief valve is located on the loader control valve. There are two different types of LCV on the 580C - Parker & Hydreco. I have included a pic of the Parker valve location as I think it is the most common. Needless to say you should test the relief pressure with a gauge to see what is happening - the spec is 2300 psi +- 50 @ 2000rpm These valves were repairable with poppets; seats; springs able to be purchased. But I haven't repaired one of these for a long time, so I'm not sure what CNH still has available.
His has a much larger cap in that area instead of the acorn nut would that be the hydreco valve setup then
Yes definitely Hydreco, parts for the valve are still itemised separately, hopefully you can still buy service items if the valve won't respond to adjustment. Well worth checking the orings on the power beyond fitting as well. This sends pressure to the BH control valve.
Ok will have to see if I can come up with a set of gauges before I go any farther
Ok got a set of gauges here is a video of what it is currently doing which is completely different from the other day it had almost no hydraulics the last time he tried to use it I’ve been playing with it for a good 20 min before taking the video trying to warm up the hydraulics some to see if it would quit first part of the video is front bucket the last part is playing with the hoe
Also just noticed that with the cap off the main relief is dripping fluid out from around the threads
When you bottom out your loader bucket and hold it what is your pressure? When you bottom out the dipper cyl. what is pressure? Also is the whole machine slow? And there will be oil leak when cap is off main relief that's why there is an o-ring on cap.
Loader will hit 2200 dipper fluctuates some between 2200 and about 1800
Ok if the machine is slow you could have a pump problem, even though you have pressure your pump could be bypassing and not giving you the flow you need. The fluctuation on dipper cyl. is prob. the circuit relief valves.
It worked good yesterday about a week ago when I noticed him having issues it had gotten to the point it wouldn’t work at all it took 20 mins to get the stabilizers up to move it out of the way he said yesterday was the best it’s been in probably the last year
When I test main relief I hold the load for longer 3-4 seconds. It should hold constant pressure & not fluctuate. Also, the relief pressure should be almost the same at idle (a bit lower) & 2000 rpm. If the relief pressure is different each time you apply load - it would indicate a problem with the relief valve. Do any other circuits move on the backhoe when the dipper is held on relief pressure? Did you inspect the oring at the power beyond fitting at the loader control valve?
What happened to make it better?
Almost all of the testing I did was at about 1200 rpm or so did not get a chance to check power beyond o rings didn’t have big enough wrenches only thing changed from previous was hooking up the pressure gauge he is going to use it as soon as it dries out some and see what it does
Is there anything special to watch for when pulling the main relief just want to be sure nothing is going to come flying out of get stuck when I unscrew it from the valve body
Here is the break down of relief valve
Take multiple pictures of it as you disassemble it. The details in Coy's image won't be good enough if get you confused on the orientation of individual parts.