Hay guys, I mentioned this before now I’m just getting back to it. On my Hitachi Ex120-2 I have a bad “hydraulic fluid” leak. Not gear oil. Fluid is coming out between the swing bearing. When I got under the machine it was dry. I saw a small what I would call an inspection plate with 2 bolts. When I removed it clean hydraulic fluid poured out. And I could see the swing/bearing gear. I’m assuming it’s from a seal in the swing motor but not sure which part. Has anyone ever seen this?
Good day there are a couple of possibilities if the swing motor passes fluid into the transmission then on it could appear in the swing ring check to see what oil you have in the transmission, the other possibility is that of the central joint. kind regards Uffex
If your swing gear box is full then it is your rotary manifold that is leaking.
Thanks mg2361 I guess you mean the swing motor. I’m thinking that’s the only thing that can leak hydraulic fluid there. But I’m trying to figure out which section of swing motor would be leaking.
More than likely the rotary manifold(central joint) that is leaking, NOT the swing motor, the rotary manifold is in front of the swingmotor/gearbox about a foot or so... have you pulled the bottom cover plate from the undercarriage?
You mean the rotary manifold for the travel? I can’t see how the rotary manifold can leak at the swing bearing.
They do.... if you pop the plate off underneath it you'll know for sure.
I did look underneath. It’s all open. I opened small plate with 2 bolts where you can see the swing gear and fluid poured out.
When you looked under there what did the manifold look like and it's hoses? Also, the question in post #3 was asked but you haven't mentioned if the swing motor gearbox was full on the dipstick or not?
There were some small drips on the fittings dripping on the ground. The gearbox is full with gear oil. The problem is leaking hydraulic fluid.
The rotary manifold (yes, for the travel) can leak from the top under the main frame which is under the rubber boot that you see looking down from the top. When it leaks it runs into the swing gear grease bath until it fills the cavity then finds it way through the swing bearing....which then you see. Since you said the gear box is full then it is your rotary manifold.
The EX series was before my time but I seem to recall that they use gear oil in the swing box, so unless the swing motor seal grenaded at the same time the swing gearbox seal crapped out the only way you'll see hydraulic oil in the centre tub is if the rotary manifold is leaking.
Well it definitely sounds like it the way you describe it. I thought the rotary manifold was mounted too low to leak there. I’m not sure where the rubber boot you refer of is. So I have to drop the rotary manifold?
If you are here asking about this then please listen to those who are trying to help you. You asked about this a month or so back and were advised that the rotary manifold is likely leaking and that is still the problem you have today. You likely will not see any oil looking at it from the bottom because that is not where it is leaking. It leaks where the center shaft goes into the rotary housing, which when it is in the machine is just below the floor of the car body. So as mg2361 said, it will fill the swing bearing grease bath area and leak out the swing bearing. If you stand in front of your machine and look between the boom cylinders you will see 4 hoses going to the rotary just above the car body floor. There is a flat rubber boot around the rotary that seals between it and the floor.
Just trying to make sure I’m understood and understand what to do next. Sorry to bother you.
I guess my time ran out about asking about the machine bogging down under a load too.
Check all controller fuses, especially the 1 amp F7 fuse. If all the fuses are good try swapping the two solenoid valve assemblies on top of your pump. If the problem becomes weak hydraulics then one of the solenoids are bad.
Thank you mg2361, I did find 1 solenoid bad and replaced both. Now no fuses blow. But still bogging. Could it have to do with throttle being disconnected. It’s had the throttle lever since I got the machine. Thanks
Oh now I realize the detached cable is for engine stop.
Engine sound? Need to rule that out first. Fuel filters, fuel supply, fuel quality? Stop lever on injection pump all the way on? Can boost pressure be obtained?
Thank you mg2361, I can’t verify all yet. Trying to repair hydraulic leak. Power washed deck yesterday and seen fluid under rubber boot of center joint. So I have to remove all hoses and drop center joint from bottom correct? When I can keep fluid in it I’ll get back to the bogging problem. I’ve changed fuel filters and found 1 banjo bolt screen clogged. Could there be more than 1 banjo bolt screen? And haven’t verified fuel supply yet. Thanks again
There can be more banjo screens but all it takes is one to bog and possibly stall the motor. Also you will need to check it after every 20 or so hours... sooner if the motor bogs again... because once you find debris in the screens it will keep clogging them.... it's just the nature of these old machines.
Thanks Ronsii, I cleaned the tank out good but need to figure out which line is delivery and check that. My machine is different than the manual shows.
That would be correct .