Case 580C weak boom, ghosting functions.

Hi. I have a 580C that I've been restoring and recently put it through it's first job - half of it anyway (fuel pump is getting rebuilt, currently). While I wait, I'm putting some work into the hydraulics. During the job the boom was weak, which got worse as it warmed up. Other functions (dipper and bucket) were not exactly overly powerful, either. Also, when the boom struggled (often), the bucket would curl, and the swing would move to the right...

I've done a bunch of searching and started going though some of the suggestions on here. One check was the power beyond fitting and O-ring to address the weak functions. I did find only half an O-ring in there - unfortunately I could not find the rest of it. That is now replaced so hopefully that helps once I get it running again.



The next step looks to be to replace some O-rings on the backhoe valves. The Load Checks (to prevent an action from going backwards at first), and the Port Reliefs (to let a function be back-driven and avoid bending things) look to be the things that can cause these issues.

I've got a set of O-rings from the dealer and am looking at how to get the valves apart. My hope would be do do this on the machine, if that is possible. I think I would have to get the spool out first to get to the port relief and load checks behind it. Does the spool come out from the top or the bottom? It doesn't look like there would be enough space underneath to drop them out. I got a cap off, but am not sure what do do from here.

I know it seems like a pretty daunting task but if you're going to rebuild the entire valve bank remove it from the machine, its a lot easier to inspect and clean all the sections as well. Do you plan on splitting the sections as well ? If so an even stronger case for removal. Just make sure to put a piece of wood or rubber under the valves when you remove it to protect from damage, that's a heavy mother.

It does seem daunting, but that is pretty much the overall theme with this hunk of yellow iron

If it's less work to remove, then it is what it is. I wasn't planning on splitting the sections - would I do that if it leaked in between them? I'm still hoping to find a good method to get to the seals I need to while it's in the machine, but I'll come around if it's the right thing to do.

Write back in how this goes and how bad it is to take out. Mine leaks some if I use the machine really hard. Just getting wrenches on some of the fittings is a chore in itself from my experience.

Unless it is leaking between the sections it would be best to not separate them. It takes a lot of expensive O rings to reseal them.
For me, removing the valve bank from the backhoe is preferred. It is way easier to get everything spotlessly clean when it is in a vice on a bench.
Take pictures of the spools before you strip them.
Do you have the service manual ?

I do have the service manual. I'll take pictures as you say. I wasn't sure if I needed to do much to the spools, but I was going to see what it looks like as things come apart and go from there.

I've done a 580 C on the machine and it's not that difficult. Like Tinker said I'd avoid taking the valve block apart is not a good idea unless necessary.

Got the valves out yesterday - took about three hours, so not bad. Very happy to be working on a bench now. I'm glad the manual told me to take off the grease fittings on the swing cylinders, because I needed every bit of space to get it out (I also should have taken off more fittings before trying to drop it out). I'm not looking forward to getting this back in place, that's for sure...



I just found out that the functions are swapped around. It explains a lot - because I added a missing restrictor in the boom port B to keep it from dropping like a rock. I wondered how the fitting and restrictor could be just missing...well it's not, it's in the next valve over (one to the left of the shiny new fitting in the picture). Now that I look at it, the stickers look to be cut out and swapped around. It's hard to see, but it goes DIPPER - BOOM - BUCKET.



It should be BUCKET - DIPPER - BOOM, which explains why the restrictor is where it is - it's where it *should* be. If this was changed without so much as moving the restrictor, it makes sense that none of the port reliefs were adjusted either?? I plan to switch it back to what it should be. Again, glad I removed this because I would not have found this otherwise, so thankyou for the advice!

Working on getting the guts out of things now. Will post more pictures (and probably questions) later.

-Jason

All the sections and the spools are shown in great detail in the parts book.
I worked on a Case loader valve that had problems and it was because someone had it apart and left a tiny spring out of it.
That totally screwed up the quick drop function for the loader.
The parts book illustration was the only way I would have known that spring was missing.

I'm glad you said that, Tinkerer, it got me to go look a little closer. The boom still dropped pretty quick even with the restrictor in place. Maybe it'll get better once it is operated from the correct valve?

Look what I found in the manual:

Yes, it should. The relief pressures should be checked after you get everything sorted out.
Lord only knows what they are after some dummy changed everything.

The little spring that was left out of the loader valve I mentioned caused the hoist to stop working whenever the boom was dropped too fast. It would start working again after sitting for several minutes.
The owner of the machine put up with it since he bought the tractor 15 years prior to me fixing it.

Got it disassembled. Next step, I think, is to take the port reliefs apart (one has a broken adjuster) and find a way pressure test them. I suppose I'll need some kind of hand pump, a gauge, and some fittings? With the spool in, maybe I can hook up a hand pump to a hose port without blanking off the rest of the manifold? We'll see how that goes... I wasn't planning on it, but like you say Tinkerer, they really should be checked - who knows what someone has set them to at this point. Would love to hear any suggestions out there on the easiest way to do this.

The "good" news is that most of the load check O-rings are missing, so replacing those should clear the ghosting issues right up - and maybe give me some more power overall.

After getting a couple of the load checks apart and seeing how they work, I decided to measure and set the pressure using a "dry" technique. No cost and less mess.

The orifice at the poppet is .245", so if it should start to open at 2400psi, to calculate the force that would be over that area (Pi*r^2 = .047): 2400 * .047 = 113 pounds. I used a scale to measure each of them and got numbers that are quite close to what they should be (at least if the hoses were in their original locations, which they were not). Boom A relief should open at 33 pounds, and the swing relief should open at 85 pounds using the same math.

I used a scale (we happen to have a doctors office style one), and a lever to apply pressure:

No hand pump and hoses ?
Are you still planning to check the pressures after you get the assembly back on and the engine running ?

No, I don't have a hand pump. I think setting it this way will get it pretty close. It will put it back about the same as it is now, and will certainly be a lot better than it was with the hoses swapped...the boom down had full pressure behind it (and the bucket open was awfully weak)!

I think it bears noting that there is a bit of judgement in setting it either way, because you have to decide how much it should be open...just barely cracked open, or open an 1/8"...1/4", it takes increasing pressure to do that. It's the same tradeoff with flow if I were measuring it with fluid... at what flow should the pressure be measured? With a hand pump the flow is next to nothing so I guess the crack open pressure is what we're after. But in operation there is a whole lot more flow, and so it must open wider to dissipate the pressure? In any case, since I was able to measure numbers so close to what they should be, I'll just put it back this way and be done with it, I think.

I see Harbor freight has a porta-power for $150 if you did need a pump. I appreciate you posting your progress with pictures. I know it takes time and effort to do that.

When you get it running check the pressure at the main relief valve in the loader control valve.
That will indicate if the pump is putting out the required pressure.

One correction to post #13, I meant to say port relief (not load check).

franklin, you got it - that pump is what I was looking at until I decided on doing this the other way... trying not to hand my wife another receipt for the tractor right now I have fun posting the progress, and it gives a chance for others with a lot more experience to point out my mistakes before, during, and after I make them!

Tinkerer, will definitely be checking the pressure with a gauge I'll be installing on the loader valve. With the power beyond O-ring replaced, I'm hoping for a big change in the backhoe. I know the pump was replaced by the last guy, so I can only hope I'm not into more time and money to attack that, but we'll see!

you need to flow meter pump

Got it back together. The valvebank is heavy enough that it laughed at me when I tried to angle it back up in position by hand. Turned out a ratchet strap did the trick. Routed it around the valves, up and out through the control/lever area and tied to the boom...ratcheted it up and lined up the holes no problem.

The ghosting is gone as hoped, and the power it should have seems to be back. The boom is more than happy to go up with a full bucket and extendahoe all the way out (it didn't before). It *almost* locks itself with an upward exuberance it never had before!

Added a gauge at the test port of the loader valves. It gets up to about 2300 psi when a function bottoms out, so I'll call that good enough (spec is 2400).

Just as a heads up to anyone looking to do this. Make sure you have around $300 in your piggy bank to do this (I did not split the valves, either). A couple of the O-rings are $12 and $9 each, so it certainly adds up. The rest of them have prices like they should be. Not sure what magic material the expensive ones are made of but I'm sure it's worth it!

-Jason