My Hitachi EX270LC is leaking hydraulic oil into the center cavity of the machine below the swing bearing. As the oil builds up, the oil overflows and runs out on the middle framework of the undercarriage. The only thing I can think of that could be causing this is that the Center Joint has a bad top seal and that hydraulic oil is leaking past that seal. Am I missing another possibility? The deck and fittings above the center joint are dry and clean. I do have the service and parts manuals for the machine, but they don't go into a lot of detail. Can anyone tell me how much work it is to pull the Center Joint and rebuild it? Any tips? Is it necessary to drain the hydraulic system? If not, is there a way to prevent losing much oil when doing the work?
It has been a few years since I've had the pleasure of this job but I can try to remember a few bits from what is left of my memory. Yes the swivel can leak into the the swing pinion tub and then ooze out the circle bearing. You can disconnect the hoses from the swivel on top and just plug them with plastic caps. There is a case drain hose that connects direct to the hydraulic tank that after you take it loose can just be tied above the level of the fluid in the tank. As I recall I positioned the stick straight up and down with the bucket fully opened and the full weight of the boom, bucket and teeth resting on the ground. After unhooking all the hoses and marking them so they went back in the right place I installed an eye bolt in the top and tied onto it with a come along attached to the boom. Take out the mounting bolts on top and the swivel drops down and out the bottom of the car body. Get all new packing for this monster since you have gone to all that work. As I recall there is about six sets of backup rings and packing rings, an oring for the top or bottom plate and a lip seal. I could be wrong on this as most of the swivels I do are on Komatsu machines. There might be a big snap ring or two in there also. When you get the thing resealed, put it back under the machine and pull it back up with the come along. Hook up all the hoses and you should be in business. The whole process took me about 6 hours last time. While you are underneath you will find an elliptical plate held in with two bolts. You can take this plate off to drain the oil out of the swing pinion tub. I would suggest you do it before dropping the swivel as you can catch that oil in a tub and then move the machine off the mess so you don't get all messy taking the hoses loose. You will have to put more grease back in the tub when you are done. There is a plate that can be removed on the floor of the house usually between the boom cylinders. Good Luck!
I agree with JohnC on this, the job shouldn't be too bad, just big fittings and big parts on a machine this size. You do want to cap the lines as you take them off as John said. Nice thing about a big machine like this is there is room for you to get down in there and do the work. I did the swivel on a little Cat 307SSR, I was turned upside down reaching in there to get the fittings loose because there was not room to climb in there. Man that was uncomfortable. Take the time to mark the hoses/fittings with a center punch, that could save you a headache when you go to re-install. Be sure and relieve the pressure on the hyd tank by loosening fill cap. Also, if the fittings on the swivel are o-ring boss fittings, take the time to replace those o-ring seals while you have it apart.
I would check your swing motor,brake for a leak. Hitachi excavators will leak oil either from the swing brake or the swing motor and that oil will fill up the area that you are talking about. If the the center joint is leaking you should be able to feel a loss of travel speed/power.
RKO, how would I check the swing motor or brake for a leak? The swing motor holds gear oil and the level for that gear oil is fine. Is there a way that hydraulic oil can leak from the bottom of the swing motor? It does appear to be hydraulic oil that is accumulating. Another question regarding removing the center joint. The service manual says to "release air pressure from tank." OK so far. Then it says "remove hose for releasing air from control valve. Set the vacuum pump and operate it." Huh? What hose, and what vacuum pump? Can someone please explain this?
swing motor/brake The swing motor oil is the same hydr. oil as the rest of the machine. The bottom seal on the motor some times goes bad and then oil is forced into the brake/reduction unit blowing the seal on the main pinion shaft and then forcing oil in to the center section. Also the seal on the main pinion shaft in swing brake will go bad, as you swing and the brake is released and applied oil is forced into the center section. Does the machine swing under load OK? If the oil is forced into the center section while you are swinging and not using other functions I would say it is the swing motor/brake. Try swinging against a load and stopping with out using the other hydr. functions if the center section fills up you know it is the swing motor or brake. The swing brake is spring applied Hydr. oil released. If it fills up while just digging it is the center rotor.
RKO, The only way hydraulic oil can get into the swing machinery box is through the shaft seal on the swing motor itself. That oil will fill the reduction box and blow oil all of the house with the oil overflowing out the dipstick. Swampdog, When the book is talking about installing a vacuum pump, they mean putting a suction on top of the hydraulic tank. It will hold the oil in the hoses until you loosen the case drain hose. I used to use the suction side of my compressor when removing hydraulic pumps. For this project though if you have plugs you woun't lose much oil. Good Luck!
If your swing brake or anything else in the swing motor is leaking, it will go into your swing reduction and blow out the lower shaft seal. So if your 90wt oil is ok on the dip stick then that's not likely the problem. Rotary manifolds are fairly easy to replace although the top hose fittings can be a little hard to break loose. Like John said, put an eyebolt in the top... I welded a nut on a couple of O-ring face caps and then attach a small piece of chain to them and use a chain come a long. When your putting it back in, be careful if you crawl under the machine to line up the manifold. I know of a dealer mechanic north of the border who was doing this and when he went under to line it up, the chain slipped and the manifold fell and hit him in the face. Not a pretty sight. The last one I did was on an EX220-2 several months ago, the owner was in a hurry and it was a sunny day with rain coming and I did it in just over 4 hours. (It did take me a day to recover) I don't usually repack them anymore because I've found that the spindle has usually got rust on it or the area where the top balls ride on is worn and needs to be machined.Around here there are several companies who sell rebuilt ones quite a bit cheaper than Deere does. Hope this helps.
Thanks everyone for the helpful replies. From what you say, it does seem quite likely that it is the center joint and not the swing motor. I guess that's good news. Excavator, can you tell me the name of the places that sell rebuilt units? And do you have an idea of the price for a rebuilt unit? Thanks.
It is pretty simple to determine where the oil is coming from. If it is the swing motor and it has pushed the seal out of the swing machinery case it (the swing machinery case) will be full of oil hydraulic oil. EXCAVATOR is correct. The way Hitachi mounts their center joint, water usually lay's in there and rust the shaft and eventually rust past the sealing surface.
Swampdog, where did you find your rebuilt unit? I have a Hitachi EX120-2 and having the same problem will oil leaking and runs out on the middle framework of the undercarriage. Anyone else please help if you know where I can get a rebuilt center joint.
Most any hyd. shop can do that or you can get reman from john deere
there are two parts that will leak on the center. it either center joint seal or swing motor seal.
Hi there Boxcar mike, is it hyd or gear oil leaking, if it is hyd oil it is most likely the center joint seals, the main seal in the center joint leaks oil into the slew bearing tub, i have had a few do this this year! Not a big job to do, i have the seals in stock if needed Aiden
Your oil flood is from the centre joint, its a bit messy to do as already stated, but the first thing to do is vent the hydraulic tank, else you will need a hell of a bath, the hitachi joints rotate on a roller bearing inside the housing, study it up and dont loose any rollers, so dont pull it to bits on the track, I do any other rotary joints on the track but Hitachi I do on a good area, you will find out why,as for the excess oil weaping through the swing bearing, just park it on a bit of a slope, it will sort its self out, I forgot to mention the big rubber thing that caps off the top works, make sure its fitted before you start poking pipes back on, strip the top pipes first, then the lower pipes, build up in reverse, I usualy leave the hydraulic tank cap unsrewed to make sure of no pressure build up, it sould take about till lunch time to do it, possibly a day if its your first 1, best of luck. p.s. I have posted a few pics of rotary couplings in shop talk.
Wow Swampdog you have some varying opinions on what it can be. It is the centre joint. As explained by someone if it came from the swing motor on an EX270 (either a Dash 1 or a Dash 5). It would leak past your motor seal into the reduction. This is filled with gear oil and is vented out a breather tube. So the question I always asked when I had the call and the person says "I have oil leaking out my bearing seal and dropping onto the carbody below". "Are you adding gear oil to your swing reduction"? NO. Then it is your centre joint. End of conversation. Go with #2 John C for disassembly assembly. It has only seals in it no o-ring back up rings. If it is an EX270 dash one. (hand operated throttle red handle pull back for more rpm). Then the only caution I can tell you on disassembly is when taking it apart, after the end cap and snap ring is off. Is to hammer with a dead blow the post out just enough to collect all the balls if you leave one in there and keep pushing it apart it will score the lands that the seals ride on. If you have an EX270-5. (dial throttle). Then you don't have to worry about this procedure. And by the way you can have the top seal leaking and have no travel problems at all. Especially a EX270-5 model for some reason the top seal going seemed to be the only reason I ever changed one. Before you take it out make note of the orientation of the centre joint. That way you can or someone else can assemble it with the same orientation so it goes back in without having to try to turn it in the machine. Good luck
It is definitely hydraulic oil. Is it best to have it completely rebuilt while I have it out?
tctractors, thanks for the info. How do I get to your pics in shop talk?
are you sure its hydralic oil,the swing box would be over full if it the swing motor seal was leaking .and if if was distributor id imagine you should have another complaint.is the machine take ing much hyd oil over a week,I would take off plate park on a slope and drain swing sump first.
boxcarmike, go to shop talk,then look for my name on the tread start, I intended posting pics of the useage of hydraulic tooling as there was some talk regards the benifit of having the stuff, it is a fairly costly tool group to have but it does bring in work that you would not normaly get, on the 22nd (I think) of this month I am going up to Berwick upon Tweed, to pull a D6C back end hollow, both F/Drives and cross shaft, this is a round trip for me of about 640 miles, I am happy to do this task as its another day, another dollar (read £) my down shift light is flashing tctractors
Halo Guys, I want a mechanic for heavy machine but I need your kindness to help me. I hope that you all can give me a donation of any excavator workshop repair manual. Help me guys....
I want to be a mechanic for heavy machine but I need your kindness to help me. I hope that you all can give me a donation of any excavator workshop repair manual. Help me guys....