Hitachi ex120-5 help needed

indigo · Oct 19, 2018

Hi everyone.

Newbie here. I bought my first excavator a few weeks ago for the farm and house project. It is a budget excavator that needs TLC. 1998 with 7000H and everything seems to be working. So far I replaced the slew bearing according to tctractor method and most of filters and fluids. Here are my 2 problems that I am seeking your help for:

1- I cannot find the parts manual. I bought one on ebay but it was limited to a few section such as pump, cylinder but not the whole excavator. Does anybody has the parts manual for this excavator or knows where to find it. I bellieve it is the gray market version.

2- I have an oil leak from the swing device, the motor that spins the excavator. When oil is added in, it will never show on the dip stick. It leaks at the bottom where the slew bearing sits. My guess is that there is a faulty seal. I am guessing that I need to remove the motor and replace defective parts. Any help would be much appreciated.

Thanks

Tractorguy · Oct 19, 2018

Swing bearing and motor assembly should be similar to a Deere 120lc that will help you in parts breakdown for knowing what should and shouldn’t be there. But it’s pretty straight forward to pull swing gear assembly up and replace shaft seal. Deere dealer may be able to look up parts you need

uffex · Oct 20, 2018

Good day Indigo
Sorry if we alarm you but maybe the swing ring movement has stressed the bearing in the transmission its worth a check. See attached hope it helps.
Kind regards
Uffex

indigo · Oct 20, 2018

Good Day Uffex

The swing ring had excessive movement so was replaced by a brand new one a few days ago. It appears to be very tight now, almost perfect but there is still sort of a backlash between the motor gear and the slew bearing gear. Would it be possible that the old swing bearing could have caused a failure of one of the motor bearing (20 or 21) and the excessive play in those bearing has damage de seal of preventing from working properly. By the amount of oil that leaks, by guess is that the seal is either partly gone orbadly broken. I will pull the motor assembly out of the excavator and bring it on the workbench and see where the leak is coming from.

Jakex120 · Oct 21, 2018

Are you say you replaced the huge 4' swing bearing?

uffex · Oct 21, 2018

Good day Indigo
From our experience and your history we would say with 90% centainty that the swing ring bearing has caused your swing transmission issue, it may be you will need to look at bearings and the final drive gear. Suggest you remove the swing transmission complete get it on a bench - repair as necessary - test by hanging it upright and fill the box with diesel fuel to check that you have got the leak.
Kind regards
Uffex

indigo · Oct 21, 2018

Jakex120 said:
Are you say you replaced the huge 4' swing bearing?

Yes the swing bearing was replaced. Was more like 43''. Heavy enough tough.

indigo · Oct 21, 2018

uffex said:
Good day Indigo
From our experience and your history we would say with 90% centainty that the swing ring bearing has caused your swing transmission issue, it may be you will need to look at bearings and the final drive gear. Suggest you remove the swing transmission complete get it on a bench - repair as necessary - test by hanging it upright and fill the box with diesel fuel to check that you have got the leak.
Kind regards
Uffex

That sounds like the best thing to do in that circonstance. What do you use to remove the large bolts that holds the motor on the frame? Impact wrench or breaker bar with extensions. It is kind of a right spot.

uffex · Oct 21, 2018

Good day Indigo
We do not have a good picture of the studs but our experience tells us that often a crowsfoot wrench can be very useful in the box for hard to reach studs, other than that advice we never ad the luxury of impact wrench in our day just determination and good tools.
Take care
Uffex

sawmilleng · Oct 21, 2018

I've always wanted to get an excavator for my stump ranch but have been put off by worry about the slew bearing being worn out.

Replacement = big dollars, even if you just buy the bearing and do the work yourself.
Would you mind telling me what that big bearing cost? Did you get one from the OEM or are there aftermarket ones available?
There must have been lots of hours on the machine for the bearing to go out, unless the previous owner was allergic to grease!

Please keep us posted on your progress-- photos are nice!

Jon.

indigo · Oct 21, 2018

sawmilleng said:
I've always wanted to get an excavator for my stump ranch but have been put off by worry about the slew bearing being worn out.

Replacement = big dollars, even if you just buy the bearing and do the work yourself.
Would you mind telling me what that big bearing cost? Did you get one from the OEM or are there aftermarket ones available?
There must have been lots of hours on the machine for the bearing to go out, unless the previous owner was allergic to grease!

Please keep us posted on your progress-- photos are nice!

Jon.

I just bought the machine from a local used excavator dealer. They had to much work ahead of them to get started on the unit so I made them an offer with the new bearing in the deal. I believe it is 2000$ for the part and it is an aftermarket. It must depend on excavator size etc. To be honest with you, changing the part was not too much of a deal. It took me and my dad a day and a half but everything went as planned, no broken bolts, no injuries etc. I could be wrong but I believe the gear must be greased plenty but the bearing itself does not like excessive grease. Grease every 500H or so rotating the bearing as you apply grease. Someone can correct me if I am wrong. The machine has 7374H. There is a picture of our setup. We used 3 bollte jack and alot of 2x10.

Jakex120 · Oct 21, 2018

indigo said:
Yes the swing bearing was replaced. Was more like 43''. Heavy enough tough.

I thought it be close to that inches..I guess that be the big concern on 7000 plus hour machine..did it freak anyone out that it looked like about 8 bolts had snapped off?..when in fact hitachi only utilizes 28 on part of the assembly.

indigo · Oct 21, 2018

Jakex120 said:
I thought it be close to that inches..I guess that be the big concern on 7000 plus hour machine..did it freak anyone out that it looked like about 8 bolts had snapped off?..when in fact hitachi only utilizes 28 on part of the assembly.

Haha ! Exactly. Before I remove the old ring I had metric boit quoted To replace the missing ones. Turns out, there is not even thread to add more bolts. What à relief. I was glad I did not have to extract broken bolts while the thing was on blocks.

John C. · Oct 21, 2018

Were those concrete building blocks under that house?

indigo · Oct 21, 2018

John C. said:
Were those concrete building blocks under that house?

Yes they were. Not the safest but we had 4 independent piles if one would fail.

indigo · Oct 22, 2018

I just got the motor assembly out. It went very smoothly. I made a 3/4 drive x 38'' extension and using a T setup with 2 prybar it was very very easy. No cursing job : ) We then used the tractor with 3pt lift to get it out. Took approx 1 hr with the right tools. We immediatly found part of the problem. The bottom seal is damaged. There must have been an 1/8'' gap at some spot. I will replace the seal but how do I check the other components such as the bearings? The gear does not appear to have much sideway play. I want to open the motor to see the other bearing but I broke my 12mm allen drive. I will have to buy another one to finish the job unfortunatly. What would else would you verify while I am at it. Few pictures attached.

indigo · Oct 23, 2018

Here are some pictures of the planetary and bearing. All the gears an bearings look alright. It appear that there is not much side play in both bearings and no grinding etc. I am planning to change the seal and the o-ring and re-assemble everything. Any other things to verify? Can the seal be procured to any bearing dealer or is it a specific excavator part that must be aquired at the dealer? Thanks for the help.

Jakex120 · Oct 23, 2018

If the seal has some whole number dimensions(metric most likely) you may get lucky and find it at bearing business. If not John Deere construction equip dealer should be able to get that. .or Hitachi dealer...seen alot of these parts on ebay too...and if you got the part number just google it and you'll get some hits for purchasing online

Jakex120 · Oct 23, 2018

To add..I gotta do this same repair eventually on my ex120-2..Every other time I use the machine I've been pouring a shot of gear oil in there.

uffex · Oct 24, 2018

Good day
I am not so sure where you might obtain a radial seal would take up Jakex suggestion and measure the dimensions
A point thats worth checking is how the seal became damaged in that way for sure we thought it was the swing bearing but it does not look to be the case, have you measured the displaced ring you may have a possible parts sale.
Kind regards
Uffex

Hitachi ex120-5 help needed

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