Had a boom cylinder head seal leaking for some time on the 322. Everyone has seen it. I really am not set up at the moment to deal with the extreme torque of the rod nut so I worked with my local hydro shop where I pulled the guts, took them the rod/head assy, they slammed my new seals in, and I thought we were winning. After about 10hrs use, the head was just seeping a touch. I was annoyed but I got stuff to do. Now I am seeing that I am actually back to losing some real oil. Like maybe an ounce a day not even running right now. Further, I notice the wiper seal is actually driving up! In my mind, I am thinking the main seal is extruding and trying to make an exit. The hydro shop is being insane great and offered to take the whole cylinder and find out what's up but I am nervous they did something damaging in there! Now I guess it could be that oil has been trapped behind the wiper and movement is causing this? IDK! All I know is I have never rebuilt one myself and had these issues. But I do know those CAT seals are insane tight! Way more of a PITA than anything else I have touched.
It sounds like the hydro shop will look at it and see what the problem is and fix it. It's not very common but sometimes something just slightly off or even a defective seal could cause a leak. Was everything lubed when you put it back together? I just had a slave cylinder leak because of the tiniest nick in the seal. I don't know why you're so panicked about this and trying to guess what the problem is. Why do say they "slammed" the new seals in? You make it sound like they purposely rushed the job and caused it to leak. You're just causing yourself undue stress. It sounds like a good hydro shop but without the full cylinder they had no way to test it after fitting new seals. Maybe you did something wrong when putting it back together? Most shops won't guarantee their work without pressure testing but respectable shops will look and see if it's something simple and generally fix it for you for little or no charge. Let the hydro shop take a look at it instead of pulling your hair out.
Hey, I always stress about stuff! That's what I do! lol I'm not insulting the hydro shop as they seemed to do everything to my request. I didn't call them with the Karen attitude, I even told them I probably have no recourse here but wanted to discuss the issue. They want the whole cylinder this time but I honestly want to be there to see what is found. I just don't usually run into stuff like this, so it puzzles and interests me. We are always installing "anti extrusion rings", but I've never seen a seal extruded. But while I am not throwing the hydro shop crap, I did have another ish with them many months back when I was there to try to get a small head seal for another cylinder. The head was obviously fresh out, needed cleaned, and I was just wanting a seal. They stuck it in for me and said "here ya go"! I was like, "I super appreciate but that head is far from clean and there was all sorts of crap in that seal groove. I just don't roll like that. But they ended up removing the seal, threw the head in the steam cleaner, and reinstalled the seal! I mean! I don't know what to think but I really appreciated their understanding. I would have been fine to just pull the seal and let me walk. If I had a remover tool that small I would have done it.
You'll just dig yourself an early grave stressing over stuff unnecessarily. Shops don't have mind readers. Some people are fine with, can you pop this seal in and they just pop the seal in. If you want it cleaned say you want it cleaned. Then there's no confusion. They might have given it to a new employee that never thought to clean it first.
Dig an early grave you say??? Ha, trust me, this isn't a guy that gets excited to see the next day. But on the seal, I guess I should have been more? clear that I DO NOT want you to install it, I just need a new Ucup in hand? I felt like they do the , "if it fits, it ships" sort of deal. Very well could have been the new guy, and I have no ill will there. They tried to make a kind gesture but I needed it right at rain. Oh well, I was just seeing if anyone had run into a similar failure so soon. Not trying to beat up one of the very few hydro shops we have. But I guess the CAT dealer is only 3mi from there, waiting for that gravy! lol
Give the shop a chance. Sometimes it doesn't take very much to cause something not to work right. My Cat engine was professionally rebuilt and the rings didn't seat. **** happens, don't be so quick to condemn the shop especially when it sounds like they want to help you. What the heck does that mean you don't get excited to see the next day? Get a cancer diagnosis and you'll change your tune in a hurry.
I don't think the inner seal is pushing out against the wiper seal, the inner seals are walled-off from each other.That outer wiper seal is hard to install properly.Some cylinders have small bolts with flat washers to help keep the wiper seal from sliding out of the packing head.I hope they get it straightened out for you.You probably know this already, but when you put the boom cyl. back on,hook up the hoses,then before you install the pin,run the cyl. all the way out,then all the way in,cycle it like this a couple of times.This will make sure all the air is out of the cyl.. Good luck with it, hope everything goes OK.
I always install the steel-backed outer wiper seals with red loctite even if there is an outer snap ring
I used to use Cat high strength retaining compound,it acted like a lube,for easier insertion,then held like crazy after it dried.
If I am worried about the wiper seal sliding up i use red locktite and if I’m really worried, like my stabilizer cylinders I just did , I will stipple the base and sides with an automatic center punch. If I’m extremely worried, I will peen or stipple it after the wiper seal is in. Lol
seems the consensus is that the main seal is not extruding and pushing the wiper, the wiper is just coming loose? Either way, it has to come apart. Cylinder only has like 40hrs on it. There was just very slight dampness when first done. Then it just got to a point it was drooling down the cylinder. I'm sure the oil is just bring in more crap and toasting that seal. I had them save the old seals for me on the first rebuild as I always want to find the smoking gun and sure enough, those seals were just timed out and were brittle and breaking. I only say that because of this deal. If it was leaking for an unknown reason, rebuilt, then still leaked, that would be a concern. We will get it out and go from there!
It can't. See below. It would have to extrude through a gap that is probably only about 10 thousandths. Did the shop get the seals 15-17 in the right way round and in the case of 16 & 17 with 17 closest to the wiper seal.? Could the old seals have possibly been in wrong and they simply copied what came out.? If so that could all put additional pressure on the wiper seal. Second all the tips regarding above the installation of the wiper seal if you want it to stay in place. My preference would be the Cat High Strength Retaining Compound (aka Loctite 620) and hit it with a centre punch at a few places around the circumference after installation.
I have no way of knowing how or what they did in the head as I had them load it up with the new seals and return it to me. I am sort of hoping they will share details or even let me go back and work with them! Seriously, this is another inch closer to just building a hydro bench. But my hydro shop is most certainly being helpful. I can't fault them. But I also don't want my stuff damaged. Let me step off on a tangent. Recently had a turbo seal to do in our box truck. NO WAY was I going to hire that done. Why? Because they would have broken off all the bolts and told me I needed a turbo. I guess I just have trust issues but I used to wrench professionally....
You have to learn to accept that even the best professionals can have odd things go wrong without explanation some times. Having an attitude like everyone is out to get you is no way to go through life. Just let the hydro shop look at the cylinder already. If your posts are just going to be a bunch of excuses why no nobody doing any kind of work can be trusted nobody is going to want to help you.
Hey Fastline, I just want to say it sounds like the cylinder shop is doing right by it, I would go in with a humble attitude and allow them to fix their mistake, I'm sure they will.
I’ll add to the above if you want to be sure then be there yourself to see what they find when they pull it apart.
One of the stabilizer cylinders I did is leaking down slowly. Wasn’t doing that before I took it off. The wiper seal was non existent and the seals were all hard. It took hydraulic power to get the rod out as my SXS was just sliding across the ground with the winch. Took a 5 lb deadblow to get the gland off. Went on like greasy peasy and gland screwed in easy as could be, even would have went past the locking screw. Being a Case with the 2’ rod, I know the seal kit from Broken Tractor is correct. Just need to get some junk in there to bind it up a bit, or use it enough to get some real heat in the hydraulics as I just completely purged the sytem. Kinda like a leaky faucet, fixes itself. lol
Back to OP. Did you bleed all the air out before putting her to work? Just asking?
A very good question. Enquiring minds will be interested in the answer.
Cylinder was cycled several times very slow, without rod end connected to boom. Cylinder was moved horizontally with ports up to encourage all air to leave. I did notice the cylinder seemed to be a bit 'tight' in that it seemed to labor the engine a touch and need more stick. This was without eye connected. I suspect that was just the new piston seal as those are stupid tight. The head otherwise moved just fine. No odd behavior during assembly. I will ask if I can be part of the tear down but i'm sure that won't work out. They are busy and prob don't need me eyeing their work. For all I know, it was something we did! I will say this, I didn't remove the barrel from the hoe so we had to install that rod horizontally where it sat. Not sure I will do that again. I find that running them vertical, the rod weight alone is usually enough to get the piston in so there is no hammering, just some smooth operating. I also want to see their hydro bench because I need to get one built. Not that we build all that many, but there is more time wasted driving and moving cylinders when we can prob spare a few hrs and have equipment back running same day.
I dunno. You are the customer. If something failed such a short time after being installed IMO you have every right to ask to be present when it is disassembled. And if it was something you did when installing the piston/rod assembly then again it might be a good idea to be there when it is pulled apart so that you can see the damage for yourself. My 2c, YMMV.
I agree! But I have also been on the other side of the stick. I use to do some forensic work on race engines. But having seen how companies work on cylinders, this is why I want to do my own. They move fast. I tend to think debris from the old seals was in the head, but that is purely a WAG! As long as there is no serious damage, hopefully we can just proceed. The cylinder appeared leak free for the first 10hrs or so, then developed just a tiny weep. Just enough to make you mad but not even enough to run down the cylinder. I would think a blatant error would have shown up instantly. I inspected the rod and requested they do the same and we both agreed it was good to go. I have found the smallest of imperfections but nothing you can really hang a finger nail in.
Was the rod checked for straightness.?
I don't think most shops would want customers in the shop when they are actually working on something due to liability. Even if they aren't actually working on your piece, they could be working on other customers pieces in near proximity. What is common though is for a shop to bring you in the back after they've done the work and discovered the issue or didn't find an issue. I've seen that before to where there didn't appear to be anything done wrong. I was brought in the shop after they took my rotary cylinder apart. They showed me that the shaft had worn a groove in it from the seal. I'm thinking that's gotta be an expensive shaft. Thankfully they said it can be metalized (spray welded) with a harder steel and be machined back to size. I didn't need to see them take it apart. Most people wouldn't want a customer looking over their shoulder or getting in the way when they're trying to work. I can just see some customers trying to tell the shop how to do it or constantly asking questions. There are many good reasons for not letting customers in the shop when they are actually working on your stuff. Sometimes there are exceptions but not often. As far as a cylinder bench there are several you can look up on the internet.
Was everything well lubricated when putting the cylinder back together and have there been any other issues with the hyd's. prior to this cylinder leaking? Also when was the hyd. filter last cleaned? It's not as critical on cylinders that the oil is clean enough but if there was even a slight bit of contamination in the circuit for this cylinder could cause a leak in short order.
Not to be picky, you didn't run to "end of travel " until you were confident all the air was out? Right? Some here will disagree, others agree. Foamed or areated oil will diesel in a cylinder much quicker than any would believe. In my younger life, ruined a set of seals by being impatient. Lasted maybe 2-3 hours. In my defense, it was a dipper cylinder on a 700, so ... kinda hard to push air downhill.
I am willing to take a good keyboard lashing in the sake of learning something here. Not a rookie here, but hydros are my least fav. Electrics are my jam. Machine has good hydro filters, CAT oil only, clean system, never a failure, no other cylinders leak, I try to keep this one "high and tight". The other boom cylinder is perfectly happy. There is nothing that leads me down the road of a system problem, but could point to something in the cylinder. Nige asked about straightness of the rod. No, we did not check that because I have never had a bent rod. Something to consider though. I am usually quite good at examining for failure modes ,thus why I wanted my old seals back. If they had looked mostly good, I might have had concern, but they had the obvious signs of being "timed out". As for how we purged, I personally feel we are extra cautious here. Cylinder was taken from stop to stop several times at about 20sec per stroke. Everything was hosed down with oil during assembly. We adjusted cylinder position to ensure air would leave (high point) sort of thing. Probably cycled the cylinder 20x, then connected and ran some slow testing. Everyone knows how the boom cylinders position in an X so head end really should stay purge without much issue. But I guess if there is air in the lower piston side, that really has no way to purge. However, air molecules are way smaller than oil so I always figure air will find it's way past that piston and make it to the head. I will say, before the repairs, that boom would stay up for days. After the repair, I didn't really test extremes but would set the bucket 1ft off the ground and it would be down the next day. I realize that points to the piston seal and they installed it on the piston and I put in the barrel. I asked that the piston be wrapped and they did that. I didn't see anything on the seal of concern. It was just a super bitch to get in! Basically in any sort of rework like this, I like to try to find that "smoking gun" to ensure we have it fixed. Go slower on air purge, precharge the cylinder, I have not decided yet.
The condition of the packing and head seals will tell you everything. I'm not trying to knock your work by any means. I'm just sharing my personal experiences to help prevent a repeat failure, if it was a contributing factor. Even when I have a hose failure, I exercise the circuit from the middle to maybe ¾ of travel in each direction slowly and deliberately as you described but going a little further each time closer to "end of stroke " each time. As you stated, it should have purged with ports on top. The air should have worked back to tank.
Wish I still had access to service info from Cat. I recall there was a warning about how to purge air from, I believe it was, the big long tilt cylinder for the bucket of the 988H. Seems it was just that some kind of warning about "dieseling" if not done proper. Maybe someone out there has access to that info? Nige? That was the only place I remember seeing anything to do with that in all the service manuals I worked with over the 45 years I worked on all kinds of machines with hydraulic cylinders. Then again the 988H does have a long tilt cylinder where compared to say a 988 87A!
Nige has posted that info on here before. I'm usually reluctant to bring it up because it usually starts an argument with "those that know better" But if a guy has a problem with a fresh install, I figure, can't hurt.
I should clarify that we never just go end to end, we move back and forth and sort of 'work up to it'. In all ways, I feel we did a reasonably prudent precycle. I know some guys that will throw a cylinder on and go to work. And they never have problems.....lol My life.....
Just an update, I am losing confidence in this hydro shop. I felt like I removed some pressure to expedite the repair, I just wanted it right. Almost 2 weeks later, I still had heard nothing so I called to hear they are "waiting on a part that should be in tomorrow".... But what concerns me more is she said "a part that goes under the piston seal was missing"... First of all, the piston was not even the primary issue, though I did note that it would bleed down, which it never did before. Still within CAT specs, but very obviously went backwards somewhere. I reinforced the fact that the HEAD was the primary issue and I want to know what happened. I think what did not really surprised me is parts were missed in the rebuild. what I personally suspect is the critical Oring between piston and rod. Or the entire energizer band? I mean, ***? I guess I am just venting as I need to explore building a hydro bench. People make mistakes yes, but I very much question the competence in that shop. Like everyone, I don't think they can find help beyond burger flippers. Frustrated.....
Maybe wait and see what they say was wrong and what part was missed/missing. Bleeding down is likely due to piston seals. If a seal was missed between the rod and piston could cause it. Some pistons are 2 piece with an o-ring in-between them. If that o-ring is missing would cause a slow leak down.
Again Dave, the primary reason for removal was the head was puking oil everywhere, and the wiper was half out. their response is "we missed a piston seal, we will get that fixed for ya".... I think my judgement decided I need to make an unannounced visit tomorrow to see this, in hopes before they try to assemble it. My gut is telling me they are trying to cover something up or they didn't give this cylinder 10min of consideration.
You said the cylinder would bleed down and it never did before. That indicates a problem with the piston seals. Maybe they missed something putting it back together. Hopefully the 2nd time they get it right. As far as it leaking at the gland nut, a wiper seal doesn't hold any pressure. It just prevents dirt getting pulled into the cylinder. I would think they'd be extra careful making sure everything is right since they have to take it apart again.
I didn't imply that the wiper was holding anything other than I've also never had one walk out. As I have learned though, as soon as the wiper failed, the head seal will fail and probably chew on the rod too. I have no idea what went wrong but I DO know that any piston seal issue did not cause the head to leak. I guess I just don't share the camp of "try again, see what happens". I've been building engines for 30yrs, and machinist for 20yrs, and that mentality gives me nightmares. I do know I recently did the tilt cylinders on my forklift and was beyond pissed that I realized the lip on the piston side of the rod was sure to screw up the head seals so we had to remove the clevis on the other end. Even made a tool for it. I realize shid happens but they should have way more tools than me. Even I knew I could just turn an install tool in our shop for that. I wondered on that job how many would just force it and go.
They are going to bullcrap you, I’m sure you are already expecting this. Stay calm, get used to being disappointed for expensive work for the future. Rebuliding a hydraulic cylinder isn’t on a phone app. Its really nothing the shop will be able to do about it in the future.
Not sure why this went any further than a phone call to xyz shop. Hey shop, that cylinder I had rebuilt is leaking, I'm dropping it off tomorrow.
First, if you were talking to the receptionist and not the service manager or tech you should take every diagnostic provided with a grain of salt, they’re there to make appointments and collect money. It very well could be missing a part on the guide nut allowing the hydraulic oil on the rod side to leak past and she misspoke. Second everyone on this earth was at some point and time was barely “help beyond burger flippers” yourself included so yeah the people might need training and unfortunately you were the client that got caught up in it. Your choices are either let them make you whole or cut your losses. I get that it’s frustrating to be kept in the dark with no communication but it’s the holiday season and your expectations should match or you’re setting yourself up for disappointment, that’s all on you. Third parts are taking forever to get anywhere right now. So let’s say they tore down the cylinder on a Tuesday, and wanted order parts. Did they ask if you wanted expedited shipping? If you said no there’s a week or more on that if their supplier had it on the shelf. Add in the holidays and yeah 2 weeks before a part comes in.
Not worth getting so stressed about it. There's not anybody on this forum that hasn't gave themselves a little shot to the head because they missed some little detail repairing something and they had to take it apart and do it over. Sometimes the minorist little detail is all it takes. In the case of a cylinder it could be as simple as forgetting or not using enough oil the internal (gland nut) seals when putting the cylinder back together. Guessing the proper torque on the piston nut could be another example. Not quite tight enough and it could come loose. Mistakes can happen that weren't intentional.
The cylinder is repaired and in my truck. My mention of the drifting the cylinder had after rebuild was ignored and only the head(rod) seal and wiper was replaced. I paid $65 for a new head seal.... I have what I am told to be my old head seal and they say it was too soft and was not a loaded Ucup design. However, they still did not install a loaded cup ,they just stuffed "one of theirs" in it. They indicate my Ucup was missing the Oring, but the guy mentioned it could have been missed and not installed. personally, I've done enough Ucups that I don't believe it was designed for one. I will probably call a hydro engineer I know to discuss so I can sleep easier. Generally I like to compare new to old. Guy was baffled that I still have my old crusty seals from that cylinder and it's because of stuff like this. The old seal appears mint and I am probably more frustrated that I am relying on someone else and I am not use to doing that. I do agree that running a loaded Ucup is primarily to prevent leakage with lower pressures when shut down.. I will agree that it started puking after sitting for a few weeks. Not acceptable but plausible issue. Nothing was said about the wiper. They replaced it and that was that. All I know is the guying doing the work was high enough I could get high just standing by him. I think he tried and I guess now we just put it back to work and see what happens. Still not all that happy with the drift issue, but it is certainly within CAT spec. I went backwards on that for some reason. I will certainly use this experience to motivate me to build a hydro table.
I'm just curious why you've mentioned building a hydro bench numerous times, and what you think it has to do with fixing your cylinder? You don't have to have a bench to repair cylinders (its easier, but not necessary), if you don't like the shop that's doing your work, take it somewhere else or do it yourself. If you don't like the seals they are giving you, order your own or call the Cat man. Its just a cylinder and seals, I'm not sure what you need a hydro engineer for. Nige posted the diagram of where the seals go. You've got all the info, get a seal kit, and if you don't trust the hydro shop, get after it. The year is almost over, less talky more worky.
Unless you have multiple machines and dozens of cylinders it doesn't make sense to build a cylinder bench. The biggest reason for a cylinder bench is for the piston nut/bolt. You can always disassemble the cylinder and just pay a shop with a cylinder bench to loosen the nut and then tighten it after you've changed the seals.
Machine back together.. Just have to see how she does. Not leaking yet though....lol As for the "hydro bench", I am not really looking to go nuts with a true 'pro' setup, but an aid to both break the rod nut, and have hydraulic assist for manipulating the components. Even moving at snail speed, it would be faster than having to haul a cylinder in and wait for work to be done. Because of our full manufacturing facility, I don't think this is too far outside our wheelhouse and I figure I could just throw the thing outside until needed. We have several hydraulic power units just sitting around as well as other goods. I figure we can help some friends out on a favor network. As for frequency, it seems like every time I turn around, something is leaking! Our farm equipment, industrial, construction, etc. And of course every single thing I buy needs hydro work. Just did both tilt cylinders in our Yale 9K fork. As I look around at the fleet, I'v had to rebuild pretty much everything.
I would never leave important tools outside to face the elements. Even under a tarp you still get condensation and rust.
Do they have rust in Oklahoma? I have seen some pickups from down there . . .
Thats western Oklahoma red dirt