EX120-3 Bleeding Air from Hydraulic System

[Egetebee]

Hi Everyone,
Looking for instructions on the procedure to bleed air from the hydraulic system on our EX120-3.
Recently replaced a final drive hose which had split and caused quite a bit of hydraulic fluid loss before it was noticed.
Topped off the hydraulic fluid after the repair and ran the machine which seems to operate normally however there is a slight pump whine that wasn't there before and I can only assume it's air.

I have the Technical and Workshop manuals for this machine but cannot find a bleed procedure.

Would someone be able to tell me where in the manuals to find instructions or provide them?

Thank you,
Egetebee

 

[funwithfuel]

Run at idle, start with bucket, exercise in and out slowly going a little farther each time . Then arm , same thing, then boom, same thing. Recheck oil level after each exercise. Then lift one side off the ground, track slowly 2-3 revolutions in each direction. Then do the other side.

 

[Egetebee]

Run at idle, start with bucket, exercise in and out slowly going a little farther each time . Then arm , same thing, then boom, same thing. Recheck oil level after each exercise. Then lift one side off the ground, track slowly 2-3 revolutions in each direction. Then do the other side.

Oh, OK.
Thank you funwithfuel!

I had found a procedure online for the Z-Axis 120 which has bleed screws on the pump and thought it might be the same for our EX120.
This may explain why I can't seem to find a procedure in the manual.

You've been a lot of help and support for myself and others.
Thank you again,
E

 

[absoluteyukon]

I've ran into stubborn air pockets in the pump housing as well. Usually there is a pump fill port that is as close to the top of the pump housing as possible. Verify your hydraulic reservoir level, loosen the fill plug and run the engine at low idle until you have a clear stream of oil coming out then tighten the plug. Usually you can work air out of the hyd system just by actuating machine functions but if not give that a try. Good luck!

 

[Egetebee]

@absoluteyukon
Thank you.
I've looked for the type of plug on the pump you describe but cannot determine which it may be as I've looked through both the Technical and Workshop manuals but cannot seem to find any clear 'bleeding' instructions for the EX120-3.
I've run the machine according to funwithfuel's directions, and while it's a little better, still hear something of a slight 'whine / air' sound emanating from the pump area.
As we're getting a lot of rain this week, I'll most likely not be running the machine till the weekend so have a little more time to figure it out.
Any insight would be appreciated.

Thanks again,
E

 

[John C.]

Odd sounds seem to come up all the time after something breaks. I a car I turn the radio up. In a machine I try a new pair of ear plugs.

 

[Egetebee]

Odd sounds seem to come up all the time after something breaks. I a car I turn the radio up. In a machine I try a new pair of ear plugs.

Heheh, yeah, actually that may be exactly the fix I'm looking for. Thanks John C!

 

[funwithfuel]

Did the machine actually starve for oil? Or did you "just"blow a hose. Realistically, you should have only had to exercise the circuit that failed. If the pumps were starved, you may have hurt them.

 

[Egetebee]

Did the machine actually starve for oil? Or did you "just"blow a hose. Realistically, you should have only had to exercise the circuit that failed. If the pumps were starved, you may have hurt them.

I didn't notice any noise or trouble before parking the machine prior to noticing the leak the next morning. The hydraulic tank was low beyond the sight gauge but only took 8 gallons to bring it back to level even after re-fill run & actuation draw down.

Would you happen to know if the EX120 actually has bleed screws on the pump or main valve body?

Thank you again,
E

 

[funwithfuel]

Post a pic of your pumps. We'll help you the best we can. Your tank should have a vented breather that maintains positive pressure in the tank so that oil is basically pushed into the pump. Maybe we should take a peak at your vent.

 

[John C.]

I don't recall there being any bleeds on a Hitachi pump.
I've seen it time and again after a failure. You become more attuned to the noise and vibration of the machine for a time. You start chasing ghosts. The way I interact with an operator doing that is to establish what normal operation is by doing stall tests and maybe even checking pressures. The upshot being, if it don't leak and the performance is normal, it's just a noise to get used to again.

 

[Truck Shop]

You have to remember once hydraulic oil is aerated/foamed it takes a while for all the tiny air bubbles to flush out. There may not be any large air pockets left in system but the
pumps will whine for a short bit until all bubbles are worked out of the fluid. JMHO.

 

[Egetebee]

Hi Everyone,
Once Again, Thank you for the support.
Presently the machine does seem to be running smoothly with less noticeable noise.

E

 

[mg2361]

Engine off. Fill reservoir. Remove plug below until oil runs out. Install plug.

 

[Egetebee]

Engine off. Fill reservoir. Remove plug below until oil runs out. Install plug.

View attachment 205603

Hmmm,
Actually.... That type of bolt may be on the pump. There is a 'Torx' type bolt directly on top of the pump but I wasn't sure.
Will look again.

Popped the bucket ram-out hydraulic line yesterday, so gotta deal with that this weekend. Tried to loosen the hose connection but Man-O-Man is it TIGHT!
Always something huh...?

Thanks again,
E