I have a 2001 580sl and have had a backhoe control valve assembly leak between the boom and stabilizer section for a couple of years. I've tried to repair this problem about 4 times and each time I take it apart it's the same small o-ring of the 4 that are between the boom and stabilizer valves. I've tried everything including leaving the 4 shims out in hopes that the o-ring would be held in place a little tighter. Even though this lasted a little while longer than normal, the o-ring has failed again. I've checked with Case mechanics and their answer is always "it's probably a warped valve", but, you have to replace BOTH valves and at about $1500 each, plus removing/rebuilding/replacing both spools, this isn't a cheap repair. Plus, I can't figure out how two matching machined surfaces held in place by 4 bolts can warp when the surface area is only about 1x4 inches. I know the pressure will reach about 3500 psi but I can't see how the temperature would get high enough to warp a valve assembly, they're built pretty solid. I'm wondering a couple of things. Could it be a bad relief valve in the boom spool allowing too much pressure and blowing the o-ring? I've never noticed it but could the o-ring recession be cracked? Has anyone tried taking a bad valve to a machine shop to have them surface both valve faces? Is there a Teflon o-ring that might hold up a little better? Hopefully someone can help. Removing the valve is a chore for a 66 year old but I've got it down to the point that I don't remove the entire assembly. I only remove up to, and including, the boom and stabilizer valves. But even so, I'm not looking forward to doing this again. Any ideas or help? Thanks.
This is one of those issues hard to advise on without looking, but I'll throw in my 2 cents. There is 2 circuit reliefs in the boom section, so its possible that they may be adjusted to high, and causing pressure spikes. The valve section could be cracked. I have seen this issue before. Clean the valve section of all oil. Use crack check spray to try and find the crack. Valve sections can warp for multiple reasons. Anything from over pressure, to the tie bolts being over torqued. You should be able to measure the valve section for warping with a straight edge and feeler gauges. Are you getting the proper o-ring for the valve section, or just one that kinda fits? Good luck
I would say for a certainty that you have a crack in the boom section. I have replaced quite a few of these over the years. Take a look at this thread here , it is about a loader control valve - the backhoe boom sections have the same issue.. Sorry, but it will take a new section to repair it.
Thanks airman and Garyhoff. I read the thread you linked to airman and I'm thinking that's probably the problem. If it is then it may actually be a good thing because I'll only have to repair or replace one section. When I get it apart this time I'll check for warps and cracks, before I'd just replace the o-rings and shims with new Case parts. There must be a used valve section out there somewhere, anyone have any ideas on how to find one? At this point I can feel my boom lever sticking a little so I'm thinking the current o-ring is destroyed and a small piece is sticking in my spool. As much as I hate leaks though, I hate having to tear this thing apart again. But again, thanks for the responses.
Update. I just spent 3 days working on a neighbors property about 2 miles from mine. When I got done and drove my backhoe home I left a hydraulic fluid trail from his driveway to mine. Crap! Then I spent an entire week removing/replacing the boom section of the backhoe valve control assembly FOUR TIMES! When I take the sections apart I can't see any cracks and a straight edge seems to show it isn't warped. Anyway, I went to Case and 16 rubber o-rings cost me $74, WOW. But, a boom control valve assembly will cost me over $2500 just for the boom section. Being retired, that's quite a hit. The funny thing is, when I complete an "attempted" repair I start the motor and check for leaks - nothing, not a drop. But, when I move the boom into transport, then move it out of transport to lower it to the ground = it starts to leak. Now I'm trying to find a used boom valve section and I'm not having much luck. Does anyone have any ideas. There's got to be a burned up or rollover 580SL out there somewhere but I can't find one. Personally, although I hate leaks I think I'm going to let it leak as long as it doesn't get really bad. A 5 gallon bucket of hydraulic fluid at WalMart is about $40.
You can get the stabilizer section used from Wenger's. They don't have the boom , but you could put in a request for it. http://www.wengers.com/parts/Constr...ZER-VALVE-SECTION-R.H.---L.H./10-253989A3.htm
Chances are that you will not see a crack, they can be just about impossible to see. Bear in mind that when the hydraulic pressure is in the valve, it can cause the hairline crack to open up and when the pressure is off, well it is just too small to see. I have had this more than once in my carreer. What Garyhoff was saying in post #2 was to use a crack check spray, something like this http://www.grainger.com/product/SPOTCHECK-Penetrant-3WU63 Here is a Youtube I found on how to use it https://www.youtube.com/watch?v=UtJTkrgvt2c
I thought about having it magnafluxed the last time I had the section out. I guess the problem is, if I have it checked and it's a crack I'm stuck with the tractor torn down and nothing to replace the cracked section with. Right now I'm trying to find a reasonable priced section but haven't had any luck. I really appreciate the help though. It's back together right now and I'll keep an eye on it but every time I see it leaking it gives me an upset stomach. And I'm pretty sure you're right. If you know of anyone that has a boom control valve section for a 580SL I'd appreciate the lead. One last question. Would a boom valve section from a 590SL or even a 580SK work?
Is your machine a foot swing or hand controlled swing ? It may or may not make a difference in your search. Keep in mind used sections are just that. They may give you problems also. You may have better luck locating an entire valve assembly. Probably cheaper than $3000.00 for two new sections.
Thanks again Tinkerer. I have Case controls (foot swing). I agree, I may have the same problem with a used section but, unless it's been cleaned I think I can tell if it's been leaking. Each section is about $2500 + taxes but I only need the boom section. I'm just irritated that I abused my equipment bad enough to create the problem. But I think it was like that when I bought it. It had 1,000 hours but the last time I took it apart I saw a JB weld repair on the bolt-mount ear of the inlet valve. The hoe has had a leak for years and I've even had Case rebuild the entire valve assembly. You can't believe the bag of O-rings and shims I have from all my frustrations. I think I'm simply going to keep an eye on it and if it gets bad enough I'll bite the bullet and pay Case their ransom. I'm still a little stunned about the 16 o-rings that just cost me $74, what a rip. Again, thanks to you and the others who responded. Being retired I've lost contact with most of the guys I knew in the business, so the contact through this board is really helpful.
What happens to the O-ring? Becomes extruded?
Oh oh , a red flag goes up for me. Did you have them rebuild it for this same problem ?
Mikebramel, most times a small o-ring (one of three small ones) breaks but one time recently it distorted kinda like a four leaf clover. I hadn't seen that before. Tinkerer, If I remember right, yes, it was because of a leak out of the control valve assembly. I took it out of the backhoe and took it to Case. They actually let me watch the rebuild. After that I did the repairs myself. So, what's the red flag? All my work was commercial so I couldn't have leaks on fresh pavement or concrete. Even on dirt the EPA would fine the hell outta you. It didn't leak bad at the time but I had some down time and decided to get it fixed. The Case repair lasted a while but it slowly gets worse each time. It's a minor drip right now but I haven't put a load on it since the last repair attempt either, I'm kinda afraid to. But, tomorrow morning I will so we'll see what happens.
I'd try 90 durometer Orings, if that failed, then look at Teflon
The red flag goes up for me because you are not the first one to have the valve apart. As a result of learning that, I cannot help but wonder if something was not quite right when it was reassembled that first time. Do you have the service manual for the machine ? If you don't, this repair is good reason to invest in one. Are you certain the dealer is selling you the correct O ring kit ? It should of had 24 O rings in it. You said it only had 16 of them. Check the parts list and see if you are getting the correct kit. Are the shims #10 & #11 in position ? If they aren't there those O rings would be in a world of hurt due to over-compression. That could be your problem. Did I mention you REALLY need a service manual ?
Tinkerer, I have the 2" thick parts manual, but not the service. Yes, the valve assembly had been apart prior to my buying the backhoe. I know this because I found JB weld on one of the valve inlet or outlet ends (not the boom). Anyway, I get my o-rings from Case so I assume they are correct. I only got 16 o-rings last time because I only took the assembly apart up to and including a stabilizer valve. Yes, I use the shims but one time I didn't between the boom and stabilizer sections and the repair lasted longer, but it failed eventually too. The o-ring that broke last time was the small bottom one. If I could remember WHICH other ones broke it would help, but I can't. But it's always the boom section, nothing else leaks at all. I'm leaning towards a crack but Mikebramel had an interesting thought, durometer or teflon o-rings. Now, where do I find those? What I'd like to do is pull the section out again, magnaflux it and either put the stronger o-rings in or, dammit, break down and pay Case for a new section. The tractor would be down a few days waiting for Case to get the section in but that's ok. The cost isn't ok and what if I put the new section in and it still leaks? Talk about a headache. One more question. I was told to torque the four assembly bolts down to 30-35 ft. pounds. If that's not right I'd appreciate knowing but I can't believe those 3/8ths bolts could stand much more torque than that. Thanks again Tinkerer. Mikebramel, how would I find those type o-rings? You'd think Case would offer them but then again, if they can get $74 out of me for 16 rubber o-rings, why would they? Hell, Harbor Freight sells kits of 225 o-rings for $9. I know, I know - it makes me feel guilty even saying I go to Harbor Freight, but I do sometimes. Half the time I go there to buy something and the other half of the times it's to return what broke. I'll figure it out someday, maybe. Thanks again.
Mikebramel, I just noticed the oring specifications on the schematic Tinkerer sent and it says "Duro." in the o-ring specs. If those are Cases part numbers I'm wondering if I have been getting Durometer all along. Anyway, each o-ring from Case has a small white dot on them, is that a Durometer? If you look at Tinkerers schematic, my leak is between Boom section #5 and stabilzer section #4.
Those O rings are 90 Duro according to the parts list. That is a hard O ring on the Durometer scale. I hope that the parts person you are buying from is not substituting something else. The 30 to 35 ft-lbs of torque sounds a little high. That is why a service manual is a must have. Those four rods need to be tightened down evenly. I would check the final torque on them a minimum of three times on all of them.
All the shims have to be correct, in good condition, and in place, otherwise one or more sections will tilt a bit and throw the whole stack off on flatness and compression. If it was me I would try Viton O-rings, they're usually brown.
This is what I love about this site, good unselfish feedback. Anyway, I did a few hours of work today using my 36" bucket and sure enough, it leaked. Not really bad but bad enough and I'm sure it'll only get worse. I've found a used 580SL boom section with the right part number and even though it's a bit rusty the pictures show it assembled with the other sections and there aren't any oil leaks. I think I'm going to have to bite the bullet. I'm waiting for pictures of a second one but the guy selling that one isn't as quick with his pictures. I'll probably pay for one tomorrow morning. Thanks again folks. Once I swap the sections I'll let you know if it worked and the guys name and number where I got the section.
Did you happen to try and buy the entire assembly. It seems a shame to separate a good complete valve assembly. You would have your original one for parts in the future. If it were me and I went through the ordeal you have, I would be buying that complete unit. I had a loader control valve that had problems once. I was sure I would never find a replacement for it. After a lot of looking I finally found one and happily paid the man $500.00 for it.
I've been following this thread with interest. As others have said, hairline cracks are not unusual in castings, they're hard to see, and they open up under pressure. But given you have actually seen o-ring failures in that valve section, perhaps it's not a crack. I wonder if the valve sections have somehow become distorted and no longer flat at the mating surfaces. Perhaps, next time you take it apart, lap the mating surface with some fine lapping compound and see what kind of visual evidence of distortion that produces. Just a thought.
Tinkerer, the boom section is complete with spools, relief valves and even hose fitting. I bought it tonight and once it's a day or two from my getting it I'm pulling mine old one out. I'm going to pull it apart, check everything and have it magnafluxed. I wish it only cost $500, I had to pay $925 shipped but it's the section that does the heaviest work so it also fails the most. These things are REALLY hard to find. In fact, I found two today and each seller sent me pictures. The crazy thing was all the pictures were exactly the same. Same finger holding up the valve, same black widow egg on it, same parts tag with the same writing and the same rust = it was the exact same valve section but from two different states! Willie59, the last time I had it apart I used a straight edge on it with a flashlight and it's hard to believe it could be any flatter. I thought about having it surfaced (like a brake rotor) but I never do. I get impatient and just put it back together thinking new o-rings will help. It doesn't. I hate to admit it but I think it's a crack because it's always a small o-ring that fails. If I can find a crack I'm going to see if I can get it brazed or repaired somehow. But if nothing else it'll give me a spare section to remove the spool and relief valves so I can see how all that crap works and goes back together. Thanks for the concern.
The method I use to look for cracks is the ink / dye method. (as seen in the other posts) You buy a couple of aerosol cans & DIY. You probably only really need to purchase the developer - last step white paint. Thoroughly clean the section with brake cleaner & dry it off, coat the section with the developer & it will pull the oil through the crack.
alrman, I saw the post about all that but had never heard of it before. Where do you get the kit? I suppose I could as NAPA or just take it to a machine shop. I've never gone to that point before because it would mean having the tractor out of service too long. Once I get my old boom section back out I'm going to take it apart so I can see how everything works in a valve section. But, I don't want to put the hoe out of service until I know my new used section is almost here or in my possession. I'm kinda looking forward to doing this replacement this time. I'm retired now and I think figuring this kinda stuff out can be helpful to others. Just removing the entire control valve assembly is challenging but after doing it 5 or 6 times I've come up with solutions where I can do it by myself. Once it's out again taking my old section apart will educate me on what makes the section tick and how I may be able to service it without removing it. O-rings, seals, etc., but right now I wouldn't take it apart because it's the only one I have. If I tried to take it apart some spring, clip, cup or something would shoot out of there and (if I could find it) I'd have no idea of where it went or how to put it back. Also, if my old section is cracked, I want to see it and then try to come up with a repair solution like brazing the crack. If I can it'll help others save money. For example, a hydraulic boom cylinder. I've cracked a couple and instead of replacing the entire cylinder I repair mine and it saves a small fortune. If anyone has questions about that my answers are free. Ask.
First, thanks to everyone who responded. I think I have my boom section leak resolved but won't know until I start digging again this week. What an ordeal. What I found was a really small gouge in my boom section. I'd seen it before but couldn't figure out how it was the problem because the o-rings broke on the opposite side of the o-ring recess from the small gouge. Plus, the nick was on the outside of the o-ring groove and it would seem that the r-ring would seal it once the o-ring was compressed. Anyway, I finally found a used boom section from a guy named Mark out of Arizona and the section was specifically out of a 580SL series 2. Plus, the valve control unit was still together. My point is I felt comfortable the section I needed hadn't been exposed to the elements. I paid dearly, $925 shipped but didn't have much of a choice because I couldn't find any other boom sections. One board member suggested Wengers and they had every section except the boom. They only wanted $500 but they didn't have what I needed so it didn't matter. Ok, I paid for my used section but when I got it the surface rust wasn't restricted to just the outside of the section as I'd hoped. The spool was stuck so I took it to a mobile mechanic that I knew. He quoted $250 for repairs but needed my old section in case anything was damaged or pitted in my replacement section. As it always turns out the repairs came to $325 and he had to use my old spool and both relief valve assemblies. When I got the section back I installed it and what do you know, my problem may be solved. The amazing thing was when I emailed Mark that the section needed repaired and the estimate was $250, Mark was apologetic and actually adjusted the price down $250. I would recommend this guy to anyone because when you buy used parts there usually isn't any sympathy or understanding about problems. Marks number is (602) 549-0681, he has access to all kinds of parts, not just Case. Again, thanks again for the help. I'm going to check my old assembly for a crack once I find the crack-check materials. If I find a crack I'm going to talk to a few machinists to see if it can be repaired. The boom sections get the biggest workout and fail most often so they are constantly in demand, which means the used replacements are few and far between.