First off, for anyone searching for drawings or part numbers on the 580B backhoe, use the parts.casece website, click find parts by model, search "35 backhoe". Should be the first result. So to my question, I took the hydraulic valve assembly off the backhoe, what parts would you replace if trying to improve the functionality and pressure from the backhoe hydraulics? My main issue is lack of power, and some movement of cylinders when operating another cylinder. Thanks!
I would suggest that you check the pump output pressure first and a flow test after that. It's all in the service manual. Then if all is good the valves would come under scrutiny along with hydraulic cylinder pistons leaking.
I've ordered the hydraulic filter and a pressure gauge. I plan to check the pressure. My assumption, and it is just that, is there are usually items in any machine that wear or are weak points, and that some of these items could be a part of the problems I'm seeing (mostly my opinion is based off research I've done). This machine has not had any service to the controls in at least 10 years other than me changing the fluid a few times, and to me that seems too long considering the condition it was in when I got it. I tend to over-do things when buying parts and repairing, so I'm not just trying to fix the problem but improve the functionality/usability.
The main problems with valves are: They leak externally so you replace the seals. The relief valves leak so you clean the gunk out of them. Maybe part of your problem? The spool and or body wears out, and or cracks. Replace both as a matched set. If you're set on taking it apart, by all means replace all seals and o rings, but don't expect it to fix anything if the o rings aren't obviously missing chunks, more like put new ones in there to hope they make it another 30 years. You'll need to reset the relief valves when done.
Awesome. Thanks. Since I have never taken one apart or know the tolerance, I will just replace things like you mention. I wish the numbers on the drawing were easier to read. Can the spool valve o-rings be replaced? I don't see them listed.
If you're thinking orings like piston rings on the valve spools, there aren't any. They are just machined to fit. Like Delmer said, I wouldn't go to the valves expecting to get any serious performance upgrade, unless your relief pressures are low.
Being an owner of a 580C, I am surprised no one has mentioned the o-rings on the power beyond fitting on the loader control valve. This is the first thing I would check. Do a search for "loader control valve " on here that The Old Man posted a couple years ago for his 580. Lots of good information about the issues you are having. I am planning on doing exactly the same thing you are sometime soon with mine. It needs to be taken apart and o rings replaced and resetting the relief valves. Joe Hynes
Good point about what might be causing the problems. By "needs to be taken apart..." I assume you mean it's leaking, and you have reason to believe the reliefs have been messed with? If it's not broke don't fix it is the golden rule of wrenching.
I am having issues with the power of the backhoe. You can hear the relief valve bypassing fluid when you lift the rear up off the ground. I am planning on servicing the loader control valve first and see if that is where the issue is first. If that doesn't fix the problem I will probably then dig into the backhoe control valve. From what I have read on here the o rings fail and you start to lose power on the hoe. I just need to get around and do it. Joe Hynes
IF you are hearing the relief valve bypassing, the relief valve is the problem. Get a gauge and a service manual before you adjust it.
I am sure there is some o rings that have failed. I pulled the power beyond fitting and the o rings on that were almost gone. What was left of them were brittle and fell apart when I squeezed them. I can only guess that all the others are in the same condition. The valve section for the backhoe has some leaks around the spools that need some attention also. I have a service manual and bought a couple gauges to check the pressures. I just need to get around and do it. Joe Hynes
I had the backhoe valve assembly off, cleaned it up, then needed to use the backhoe again so I never dug deep into it. I have connected a pressure gauge to the side port on the loader stick area; I am seeing 2250 psi max while using the loader or backhoe. But I still feel there is not enough pressure applied at the backhoe. For instance: the bucket cylinder will not rotate with the weight of the backhoe on it. The boom cylinder has always been less capable than the dipper cylinder when picking up things. Any direction? I have the gauge and looking to put it to use - maybe I need some adapters to check pressure elsewhere. I didn't see any 1/4" ports where this gauge would fit. PS. I bought a service manual from tradebit many years ago, but now I can only find one of the 4-5 parts they sent me. No good.
In regards to the boom cylinder lack of power --> does the boom slowly go down when you raise it all the way up and then shut off the engine ? If it does you have internal leakage problem from a worn out piston packing. You need to get a service manual when you have problems like you are experiencing. Here is an example of what is in it.
My boom cylinders on every backhoe have had less lifting power the the dipper & the style of bucket will determine whether or not you can lift the machine curling it backwards not so sure that's a critical thing in determining digging power.
I pulled this valve assembly off my 580 B to fix several leaks , o ring / seal kit did the trick simple enough I think by design when you are performing 2 separate functions with the control valves you will have less power to one or the other , my swing pedals tend to stick at times and it will rob hyd fluid / pressure from other functions , Now out of habit , I kick them a little to be sure that one swing cyl or the other isn't trying to move the hoe. Your pressure seems to be adequate but Not really sure , if you can bog the engine down with a load , I would guess the hyd pump is putting out plenty , good luck
When you say seal kit, do you mean a prepackaged kit of seals to rebuild the entire stabilizer leg twin valve assembly? If so, where did you get this kit? If I'm going to pull this turkey I want to do it once and do it right.... Bart Laveen, AZ
Any local CNH agricultural dealer can get any of the parts you need. I would never put anything but OEM parts in a control valve. Some of the O rings are unusual like ---> #8 & #9 in your picture are an example. Notice that they are referred to as quad rings.
I am wondering which valve group do you have. Is it the commercial, cesna, or case valve? There are different fixes for each valve.
Hmmmmm, Interesting day today.... I pulled up on the valve in question and it actually pulled the spool 1/4 of the way out and then I pushed it back and it seated correctly. Now now leaks and it works properly up and down. Of course this means there are parts missing on top of this spool that should prevent it from coming so far out. I'm thinking of just pulling this spool and not pulling the whole valve assembly. 6 hoses and who knows how many bolts and the other valve works fine. I tried to look up the parts in the CMH homepage but it only shows the complete valve assembly. Well, it works for now...... Any suggestions on what would be missing if the whole spool comes out the top? Bart Laveen, AZ
Typically a hydraulic valve spool has a spring loaded mechanism at the bottom that centers the function. Usually it's in some sort of die cast cover held on with two little bolts/screws, sometimes they're threaded in. They're not supposed to seal, just hold the spring in place, the bolt inside of that cover came out of the spool, that's my guess. take it apart carefully, on clean concrete if possible, try not to lose the little parts.
Bart ; You are asking questions about the same machine and problem in two different threads. It is makes it difficult to help whenever a member does that. To answer your last question in this thread, if you found the complete assembly in the parts catalog the individual sections are there also.
Thank you everyone..... This is posted in two posts (Oops, didn't mean to do that.) Based on this post and the other post, I don't have to pull the valve apart, just the bottom cover on one spool. (and I'll do that over a clean white bucket.) It is more than likely just one bolt that broke or fell out of the spring assembly.) Ending both threads with this Thank you everyone, you made my work so much easier. Bart D. Hull Laveen, AZ.