The turntable on my hitachi UH083 excavator is leaking bad. I’m curious what the problem is likely to be, and how to go about fixing it. I checked for play in the slew bearing by lifting the tracks off the ground slowly and watching for play. I did not see any play in the turn table. Are there multiple seals in there that need replacing every so often? I imagine this is a big job no matter what the problem is. Here are some pics if this is helpful at all.
Have you been adding more than normal amounts of hydraulic oil, lately? Looks like your swing motor output shaft seal is leaking.
Gotta go with swing box pinion seal on that one. UH series was wayyyy before my time but I'd start with checking the level in the swing box. If its way low, that is likely your culprit.
I'd suspect the swing box to be over full, not empty, from a leaking swing motor shaft seal, assuming the swing motor and swing gearbox are separate, yet bolted together components. Once the hydraulic oil leaks past the motor shaft seal, it will over fill the gearbox until it comes out either the breather or the output seal.
Like was said before, have you been going through more than the usual amount of hyd. oil? Also check your swing gear box oil level. There should be an oval plate with two bolts somewhere on the floor, either between the boom cylinders or to the right of the boom? I'm not sure on a UH model, but if you can find that then take it off and check what for liquid is in there. If you can't find the plate then crawl under the machine and look up on the bottom of the floor, there should be either an oval plate or a plug that you can drain that cavity. But be careful, if it's full of oil and water, you can take a shower real fast. Make sure you have a couple of empty buckets ready. The one picture shows some milky white oil dripping. If there's water in there it is likely coming through the boot around the rotary manifold, check to make sure it is down tight onto the lip on the floor or look for cracks. If there is gear oil in there and your swing drive is low then your lower swing drive seal is leaking. If there is hydraulic oil and gear oil in there it's likely your swing drive motor seal is out, which would push the lower swing drive seal out, dumping both gear oil and hydraulic oil in the cavity. If it's just hydraulic oil then it's probably your rotary manifold leaking. If you need more let me know, I think I still have a few UH service manuals around.
But, on the bright side, your swing bearing is lubed. Ok, I am going to bed before I get in trouble
I checked the parts website and it looks like the upper plate is between the right boom support and the box. The lower plate is towards the idler end of the frame.
Looks like gear oil to me. Check and monitor the oil level in the swing transmission before this $3K repair turns into a $15K repair.
Hydraulic oil can also get into the swing pinion tub from a leaking swivel on some, if not most of, the Hitachi excavators. Swing gear box level is the key. The oil flow into the tub has to be continuous for that amount of oil to fill the tub and drain out through the swing bearing. The color of the oil in the photos is sometimes caused by the type of grease in the tub.
I’ll, try to answer as best I can. Part of my issue is I’m not experienced in the terminology you guys are all using, such as the difference between the swing box, tub, swing motor, shaft seals etc. so I need to do some reading on what is what. the excavator had been sitting for about a month of not being used. Everytime I use it, I bleed the air pressure out of the hydraulic tank, because if I don’t, it will seep fluid out of various leaks over time, which of course need to be fixed as well... So, normally if it sits a while and I forget to bleed that air out, it will seep out and leave some drip stains in the dirt from a cylinder seal or two, not really anything alarming, and I rarely add fluid. However, this time was different. I have noticed excessive leaking around that turn table over the last few times using it, but I had over greased the heck out of that swing bearing a while back, and I just thought maybe that had something to do with it and it would slow down after the grease wore down a bit (sounds stupid now that I’m typing it out) however this time I forgot to bleed out the air pressure in the tank, and after it sat for 4 to 5 weeks, I came back and had to add a ton of fluid. It took 17 gallons of hydraulic fluid to get it back up to the right level. I’ve never had to add more than a couple gallons at a time and that was very rare I had to even do that. So, it’s obviously gotten considerable worse recently. I will check the level in the swing motor again,but it seemed fine when I checked it a week ago. I normally don’t use this much but I’m working on a big project at my house moving a lot of dirt so I’m noticing it a lot more. Aside from this major leak, this thing has been fantastic to own. I understand the swing motor, but I only know of one dipstick to check fluid level in?
I have a sheet somewhere that compares the Hitachi vs Deere machines but not sure right now where it is. I would guess that a UH083 should be something close to a 200 size machine. If you go to the Deere parts site you can look up 790-792 excavators (not D or E series) which would be a 220 size and they will be basically the same other than the engine. At least it will give you an idea of what is what. The swing drive box will have the dip-stick on it, the swing motor sets on top of that, the shafts in the motor and drive will have seals on them. The tub is the area around the swing bearing between the track frame and the floor of the main frame. The swing drive and rotary manifold go right through the middle of the tub. The rotary manifold (swivel) is located in front of the swing drive where the four hoses for the travel motors go through the main frame floor.
only thing to add to that is that there is no dipstick for the swing motor because it runs on hydraulic oil, when those seals leak, they will leak hydraulic oil from the hydraulic system into the swing gearbox, which will then leak into the tub, which is where your oil is coming out.
Piston, I read your latest response rather quickly and just now started thinking about what you said. If it leaked that much hyd. oil out over the 4-5 weeks I'm pretty confident that your rotary manifold (swivel) is leaking. There is a tank line that runs directly from the tank to the rotary and if the upper seal on the rotary is bad it will cause this.
Thank you for being patient with my lack of understanding with these parts. I appreciate the explanations and am learning as I go. I screenshotted these two pics from the service manual. Is the suspected leaking seal that you are referring to in one of these? Also, am I hurting anything by running it as is in the meantime? I used it for a few hours today and just kept checking the fluid levels.
I guess it depends how much you are running it. You are basically washing the grease out of your swing bearing, granted, it is with oil but you still need the grease. The first pic that you posted is of the swing drive mechanism and the second is of the swing bearing. You need to look for the rotary manifold.
I think the UH series is before the Hitachi/JD partnership. UH083 looks to be a size under a 200 class machine.
Pulling out this stick, is it over full, under full, is it still gear oil?
The 490,590, 790 & 792 Deere's were all Hitachi built machines (same as UH model). It wasn't until 1988 that they actually formed a partnership but were working together before this. In 1988 Hitachi went to the EX series and Deere the D series.
Are you having any problems with travel motors when machine warms up? When my rotary manifold went bad I lost travel on 1 side or other. I have hitachi uh143 same as 792 deere except engine. I also had to relieve air pressure in hydraulic tank to avoid mess next morning.
I didn't realize there were more replies after my previous post. Checking the level, it appears to be the correct level, however it appears to be all hydraulic fluid, I don't see any dirty/thick gear oil at all??? So somehow hydraulic fluid is obviously getting in there? How??? I'm still unsure what part the 'rotary manifold' is? However, I'm not noticing a problem with a travel motor. Really the only symptoms I'm noticing, is a bunch of hydraulic fluid squeezing out the turntable with the grease. I had my 7 year old sit in the cab and slowly push the boom into the ground to lift the front of the tracks a few inches, while I watched for excessive play in the turntable. I could not see any movement up/down indicating any play in the turntable. It seemed tight as could be.
That's interesting you also have to bleed the air out. Where do you see the fluid leaking out if you don't bleed the air? Is this a common system on all larger excavators? I told a friend of mine that also owns a smaller excavator that I had to bleed the air out after using it and he thought I was crazy
its the rotary manifold they are steel piped top and bottom and after all these years a little play in the house bearing pulls it as u rotate it the rotary manifold in these runs on steel balls on top and bottom and wear into the center post giving wear and leaks we used to change the top pipes to hoses to stop this problem it will be very expensive to repair this rotary and do not try to push it apart until all the balls are removed
My rotary manifold in uh143 also has the steel lines, what a pain. The hydraulic tank is pressurized with air via the compressor in order to prevent oil starvation at pump. You have air pressure gauge in cab. I dropped my manifold out the bottom with come along, it's to heavy to do by hand. Installed same way. The rotary hasn't been manufactured for years, had to get a reman from john deere, same as 792. With core was about $5,000.
Like 580bob said the ball bearings dug a notch into the barrel, oil lost pressure to drive motors especially when warm. If your not having any problem with traveling I doubt it's the rotary. That's my 2 cents.
Is the rotary manifold something that would start this leaking around the turntable 'all of a sudden'? It seems that if it's caused by something wearing, it would be more of a slowly worsening effect? I don't use the machine very often, it's just a 'yard' machine that I use on my own land, so this wear would seem like it would take a while. Last fall when I was using the machine I didn't have this problem. I don't really know when it started but at some point this spring when I was doing some excavation around my property, I noticed an excessive amount of leakage, then cleaned up around the turntable after adding some more fluid and I could tell there was a noticeable difference in the amount that was leaking out. Not only that, but it also was apparent it was hydraulic fluid vs. grease, whereas before I always had some grease spillage around the turntable. Is there something else it may be? Would one of those gear motor seals cause this? I don't know the different ways that hydraulic fluid can get into the turntable to leak out, and I'd like to learn more about it. Thank you all for the replies.
Okay, this all makes a lot more sense to me now. I didn't realize that the "Rotary Manifold" was another name for the "Center Joint" as it's listed in my service manual. I see the balls that you guys are referring to, and some seals/o-rings. Being that the symptoms were not very gradual in that the leak got bad really fast, would it be possible/likely that rain/snow could have froze over the winter causing seal or o-ring failure and that is my problem instead of the balls? Would this failure explain the lack of gear oil in my swing gear motor? If this would also cause the hydraulic fluid to get into my swing gear motor then it does sound like this is certainly my issue. Also, I haven't noticed anything different with the track motor or 'weak' final drives, however I read this article http://info.texasfinaldrive.com/shop-talk-blog/swivel-joint-or-travel-motor and it was a good explanation for me of why the center joint failure can also cause track drive issues. I really haven't noticed this, but I also haven't really moved the machine long distances or uphill since I've noticed the leaking, so I'll have to test that out in a couple weeks when I get a chance.
When you stand in front of the machine between the 2 boom cylinders, looking back where the top of the rotary manifold is, you'll notice a rubber boot that covers it. If that boot is cracked or dislodged water can enter the manifold. There are a few holes around the edge of that flat area surrounding the manifold so rain water can drain away. Leaves collect and block the drains making it possible for water to get into the manifold. There is also a grease fitting to lube the manifold that goes into the rubber boot.
I will make sure to clean that area out. I can confidently say that there are leaves/debris in there so I'm sure any drains have clogged. When I was looking under the machine, there is an oval plate with two bolts underneath the excavator body (between the tracks, laying on my back, looking up in the center of the machine). Is that a drain for the area you are referring to? Should there be grease in there, hydraulic fluid, or??? And if I drain it/clean it out, what and how do I refill it?
That plate is there to protect the lines that feed the rotary manifold. Most remove that cover and leave it off unless your your in some really muddy conditions it's not likely anything is going to get that far up anyway. The water drains to the sides of that flat area not down where the plate is. There is a small access hole covered by a plate about 3 or 4 inches wide where you put grease on the turn table gear. That plate probably is fastened by 2 bolts, your machine has a tool box in the step on left side I believe. Inside that box on the bottom is where that grease access cover is. If it's not there stick your head into that flat area between the boom cylinders to the left.
My service manual doesn’t show me part numbers. Is there a good website to purchase the center joint seals from for these old machines? Does anyone happen to have a parts reference for those seals? I’ve found a couple of online sources that seem somewhat “sketchy”, where I have to put in all my contact info and they will get back to me with information???
Check with your John Deere dealer, they are Hitachi parts dealer too. Give them your model and serial # and see what they come up with. Before you order the seals I woud pull the joint first. If the ball bearings have worn a notch in the barrel, new seals won't work. You'll need to find a re-manufactured or have yours repaired.
be ready for a really large bill and i would change the top pipes to hoses or it will wear fast as the turntable bearing will be fairly worn and start the process all over gain very quickly use only a very qualified rebuilder for that rotary joint as they are very tricky to do right
As some have mentioned. It’s your center joint also called the rotary manifold or center swivel. Top seal in it is leaking externally and filling up your grease tub. It is the component dead center of the machine. UH083 was the North American imported. Same as “Grey Market” UH07-7. 200 size machine. Kind of a pig to get out with all steel lines going to it. Don’t ask me how I know.
You have to take it apart the right way so the steel balls don’t score the seal surface. Don’t worry about the groove they balls have made as long as the post is not contacting the barrel.
I think he is referring to the oval plate up inside the track frame, in the rotary manifold area. This is a drain, be careful when you loosen it because you can take a bath real fast. I always remove one bolt and then slowly loose the other a turn . You might have to tap on the plate to loosen it then slowly loose the second one.
Hey KenAl, haven't seen you on here much lately. Go to see you back.
I have actually resealed a few, even if there is a groove where the balls set. Especially since it's a machine that doesn't get used alot. The other thing you can do is bring it to a machine shop and have them bore the housing and build a brass bushing to press into it.
Brand new the balls have an interference fit. You press it together. The balls then cut a groove. If you wanted to you can get oversized balls minus 1 but would need to machine. Like I said if the post doesn’t contact the barrel. Just reseal it. Reuse the balls. Taking it apart. Make sure the post is down. Pull the plate off the barrel. Pry out the balls under the plate. Now you have to pull the barrel up. I have a home made puller. Gravity will keep the other set of ball bearings down. Pull the barrel up just enough to pick out all the ball bearings. If you do it on the side or the other way around you risk the balls scoring the seal surface.
Ken/Excavator, When you guys are referring to the “top seal” leaking in the center joint, can you tell me which seal(s) your referencing one the attachments? it appears there are only a few seals I could replace, the O-rings and the set of 5 seals as shown.
This may be a more helpful “all in one” diagram.
Did you ever figure out the refill quantity and oil spec for this?
It's 80W-90 gear oil and you fill it to the dipstick level. John Deere specs GL 5 for my 120. When you drain it, if it has been a long while it may not come out nicely. I poked a wire up in there and loosened the tar that was in the drain tube, and went away a while. Pretty soon this ugly looking "slug" started crawling out of the tube. It was disgusting! It slowly flowed out and when it was done I flushed it with more gear oil for a bit.
I used to have a UH083 machine. It would slobber into the turntable housing all the time. Mine was a bad seal on the swing drive. Bugger to pull that swing drive out but easy changing the seal once out.Those machines had a compressor that put pressure into the hydraulic tank. If you didn't bleed off the pressure at the end of the day on mine oil would leak into the final drives too.